Lévothyroxine : interactions médicamenteuses

Patients suspected of developing thyrotoxicosis should be managed carefully to avoid abrupt withdrawal of beta-adrenergic blocking agents that might precipitate a thyroid storm. (notice Brimonidine et timolol, Mises en garde et précautions)

Presence of uncontrolled non-gonadal endocrinopathies (e.g., thyroid, adrenal, or pituitary disorders). (notice Choriogonadotropine alfa, Contre-indications)

Clomiphene citrate tablets are contraindicated in patients with uncontrolled thyroid or adrenal dysfunction or in the presence of an organic intracranial lesion such as pituitary tumor (see INDICATIONS AND USAGE). (notice Clomifène, Contre-indications)

When concomitant administration of corticosteroids and levothyroxine is required, administration of corticosteroid should precede the initiation of levothyroxine therapy to avoid adrenal crisis. (notice Dexaméthasone, Mises en garde et précautions)

Patients suspected of developing thyrotoxicosis should be managed carefully to avoid abrupt withdrawal of beta-adrenergic blocking agents that might precipitate a thyroid storm. (notice Dorzolamide et timolol, Mises en garde et précautions)

WARNING: RISK OF THYROID C-CELL TUMORS In male and female rats, dulaglutide causes a dose-related and treatment-duration-dependent increase in the incidence of thyroid C-cell tumors (adenomas and carcinomas) after lifetime exposure. (notice Dulaglutide, Mise en garde encadrée)

Reactions including anaphylaxis have been reported [see Adverse Reactions (6.2) ] High levels of FSH indicating primary gonadal failure Presence of uncontrolled non-gonadal endocrinopathies (e.g., thyroid, adrenal, or pituitary disorders) [see Indications and Usage (1.1 , 1.2 , 1.3) ] Hypersensitivity reactions to streptomycin or neomycin. (notice Follitropine, Contre-indications)

Do not take thyroid hormone replacement therapy within 2 hours of dosing with LANTHANUM CARBONATE. (notice Lanthane, Interactions médicamenteuses)

WARNING: RISK OF THYROID C-CELL TUMORS • Liraglutide causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures in both genders of rats and mice. (notice Liraglutide, Mise en garde encadrée)

Patients suspected of developing thyrotoxicosis should be managed carefully to avoid abrupt withdrawal of beta-adrenergic blockade which might precipitate a thyroid storm. (notice Nadolol, Mises en garde)

Patients suspected of developing thyrotoxicosis should be managed carefully to avoid abrupt withdrawal of beta-blockade which might precipitate a thyroid crisis. (notice Pindolol, Mises en garde)

Avoid abrupt withdrawal of beta-blockade, which may precipitate a thyroid storm. (notice Propranolol, Mises en garde et précautions)

WARNING: RISK OF THYROID C-CELL TUMORS • In rodents, semaglutide causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures. (notice Sémaglutide, Mise en garde encadrée)

Thyroid Abnormalities Avoid abrupt withdrawal of beta-blockade which might be followed by an exacerbation of symptoms of hyperthyroidism, including thyroid storm. (notice Sotalol, Mises en garde et précautions)

Patients suspected of developing thyrotoxicosis should be managed carefully to avoid abrupt withdrawal of beta-adrenergic blocking agents that might precipitate a thyroid storm. (notice Timolol, Mises en garde et précautions)

WARNING: RISK OF THYROID C-CELL TUMORS In rats, tirzepatide causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures. (notice Tirzépatide, Mise en garde encadrée)

People who have thyroid problems (hyperthyroidism) may have a higher chance of having a hypertensive crisis. (notice Tranylcypromine, Mise en garde encadrée)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Drug or Drug Class Effect Beta-adrenergic antagonists e.g., Propranolol > 160 mg/day) In patients treated with large doses of propranolol (> 160 mg/day), T 3 and T 4 levels change slightly, TSH levels remain normal, and patients are clinically euthyroid. (notice Lévothyroxine, Interactions médicamenteuses)

Levothyroxine The bioavailability of alendronate was slightly decreased when BINOSTO and levothyroxine were co-administered to healthy subjects [see Clinical Pharmacology (12.3) ] . (notice Acide alendronique, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Amiodarone Amiodarone inhibits peripheral conversion of levothyroxine (T4) to triiodothyronine (T3) and may cause isolated biochemical changes (increase in serum free-T4, and decreased or normal free-T3) in clinically euthyroid patients. (notice Lévothyroxine, Interactions médicamenteuses)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Oral Anticoagulants Levothyroxine increases the response to oral anticoagulant therapy. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Oral Anticoagulants Levothyroxine increases the response to oral anticoagulant therapy. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

An initial increase in serum FT 4 is followed by return of FT 4 to normal levels with sustained therapeutic serum salicylate concentrations, although total T 4 levels may decrease by as much as 30%. (notice Lévothyroxine, Interactions médicamenteuses)

An initial increase in serum FT 4 is followed by return of FT 4 to normal levels with sustained therapeutic serum salicylate concentrations, although total T 4 levels may decrease by as much as 30%. (notice Lévothyroxine, Interactions médicamenteuses)

Drug or Drug Class Effect Beta-adrenergic antagonists e.g., Propranolol > 160 mg/day) In patients treated with large doses of propranolol (> 160 mg/day), T 3 and T 4 levels change slightly, TSH levels remain normal, and patients are clinically euthyroid. (notice Lévothyroxine, Interactions médicamenteuses)

Drug or Drug Class Effect Beta-adrenergic antagonists e.g., Propranolol > 160 mg/day) In patients treated with large doses of propranolol (> 160 mg/day), T 3 and T 4 levels change slightly, TSH levels remain normal, and patients are clinically euthyroid. (notice Lévothyroxine, Interactions médicamenteuses)

Monitor thyroid function before initiation of, and periodically throughout, treatment with INLYTA. (notice Axitinib, Mises en garde et précautions)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

An initial increase in serum FT 4 is followed by return of FT 4 to normal levels with sustained therapeutic serum salicylate concentrations, although total T 4 levels may decrease by as much as 30%. (notice Lévothyroxine, Interactions médicamenteuses)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Drug or Drug Class Effect Beta-adrenergic antagonists e.g., Propranolol > 160 mg/day) In patients treated with large doses of propranolol (> 160 mg/day), T 3 and T 4 levels change slightly, TSH levels remain normal, and patients are clinically euthyroid. (notice Lévothyroxine, Interactions médicamenteuses)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Monitor and replace thyroid hormone if needed. (notice Bexarotène, Mises en garde et précautions)

Androgens/Anabolic Steroids Asparaginase Glucocorticoids Slow-Release Nictonic Acid These drugs may decrease serum TBG concentration. (notice Lévothyroxine, Interactions médicamenteuses)

Drug or Drug Class Effect Beta-adrenergic antagonists e.g., Propranolol > 160 mg/day) In patients treated with large doses of propranolol (> 160 mg/day), T 3 and T 4 levels change slightly, TSH levels remain normal, and patients are clinically euthyroid. (notice Lévothyroxine, Interactions médicamenteuses)

Drug or Drug Class Effect Beta-adrenergic antagonists e.g., Propranolol > 160 mg/day) In patients treated with large doses of propranolol (> 160 mg/day), T 3 and T 4 levels change slightly, TSH levels remain normal, and patients are clinically euthyroid. (notice Lévothyroxine, Interactions médicamenteuses)

Oral Anticoagulants Levothyroxine increases the response to oral anticoagulant therapy. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

An initial increase in serum FT 4 is followed by return of FT 4 to normal levels with sustained therapeutic serum salicylate concentrations, although total T 4 levels may decrease by as much as 30%. (notice Lévothyroxine, Interactions médicamenteuses)

An initial increase in serum FT 4 is followed by return of FT 4 to normal levels with sustained therapeutic serum salicylate concentrations, although total T 4 levels may decrease by as much as 30%. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Les compléments de calcium peuvent réduire l'absorption de ces médicaments ; prenez-les à plusieurs heures d'intervalle. (NIH Office of Dietary Supplements, Calcium)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Phenytoin and carbamazepine reduce serum protein binding of levothyroxine, and total and free T4 may be reduced by 20% to 40%, but most patients have normal serum TSH levels and are clinically euthyroid. (notice Lévothyroxine, Interactions médicamenteuses)

Drug or Drug Class Effect Beta-adrenergic antagonists e.g., Propranolol > 160 mg/day) In patients treated with large doses of propranolol (> 160 mg/day), T 3 and T 4 levels change slightly, TSH levels remain normal, and patients are clinically euthyroid. (notice Lévothyroxine, Interactions médicamenteuses)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Concomitant use with colesevelam hydrochloride may decrease the exposure of the following drugs: Drugs with a narrow therapeutic index (e.g., cyclosporine), phenytoin, thyroid hormone replacement therapy, warfarin, oral contraceptives containing ethinyl estradiol and norethindrone, olmesartan medoxomil, and sulfonylureas (glimepiride, glipizide, glyburide). (notice Colésévélam, Interactions médicamenteuses)

Drug Interactions Cholestyramine for Oral Suspension USP may delay or reduce the absorption of concomitant oral medication such as phenylbutazone, warfarin, thiazide diuretics (acidic), or propranolol (basic), as well as tetracycline, penicillin G, phenobarbital, thyroid and thyroxine preparations, estrogens and progestins, and digitalis. (notice Colestyramine, Interactions médicamenteuses)

Oral Anticoagulants Levothyroxine increases the response to oral anticoagulant therapy. (notice Lévothyroxine, Interactions médicamenteuses)

Androgens/Anabolic Steroids Asparaginase Glucocorticoids Slow-Release Nictonic Acid These drugs may decrease serum TBG concentration. (notice Lévothyroxine, Interactions médicamenteuses)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

…1: Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

…1: Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

An initial increase in serum FT 4 is followed by return of FT 4 to normal levels with sustained therapeutic serum salicylate concentrations, although total T 4 levels may decrease by as much as 30%. (notice Lévothyroxine, Interactions médicamenteuses)

Digitalis Glycosides Levothyroxine may reduce the therapeutic effects of digitalis glycosides. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

…1: Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Oral Anticoagulants Levothyroxine increases the response to oral anticoagulant therapy. (notice Lévothyroxine, Interactions médicamenteuses)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Oral Anticoagulants Levothyroxine increases the response to oral anticoagulant therapy. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Abnormal Thyroid Function Tests Dose-dependent decreases in serum T3 and T4 (free and total) values have been observed in patients taking APTIOM. (notice Eslicarbazépine, Mises en garde et précautions)

Drug or Drug Class Effect Beta-adrenergic antagonists e.g., Propranolol > 160 mg/day) In patients treated with large doses of propranolol (> 160 mg/day), T 3 and T 4 levels change slightly, TSH levels remain normal, and patients are clinically euthyroid. (notice Lévothyroxine, Interactions médicamenteuses)

…1: Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

…1: Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

…1: Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

…1: Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

…1: Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

…1: Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

…1: Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Le fer réduit l'absorption de ces médicaments ; prenez-les à quelques heures d'intervalle. (NIH Office of Dietary Supplements, Iron)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

…Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Androgens/Anabolic Steroids Asparaginase Glucocorticoids Slow-Release Nictonic Acid These drugs may decrease serum TBG concentration. (notice Lévothyroxine, Interactions médicamenteuses)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Oral Anticoagulants Levothyroxine increases the response to oral anticoagulant therapy. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

…1: Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

Furosemide has been shown to inhibit the protein binding of T4 to TBG and albumin, causing an increase free T4 fraction in serum. (notice Lévothyroxine, Interactions médicamenteuses)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Oral Anticoagulants Levothyroxine increases the response to oral anticoagulant therapy. (notice Lévothyroxine, Interactions médicamenteuses)

…recommended that appropriate references first be consulted to determine the usual precautions for the use of the other drug; e.g., when epinephrine is injected along with hyaluronidase, the precautions for the use of epinephrine in cardiovascular disease, thyroid disease, diabetes, digital nerve block, ischemia of the fingers and toes etc., should be observed. (notice Hyaluronidase, Interactions médicamenteuses)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Thyroid function should be monitored periodically. (notice Interféron bêta-1a, Mises en garde et précautions)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Drug or Drug Class Effect Beta-adrenergic antagonists e.g., Propranolol > 160 mg/day) In patients treated with large doses of propranolol (> 160 mg/day), T 3 and T 4 levels change slightly, TSH levels remain normal, and patients are clinically euthyroid. (notice Lévothyroxine, Interactions médicamenteuses)

Thyroid Function Abnormalities : Decreases in thyroid function may occur; perform tests where clinically indicated. (notice Lanréotide, Mises en garde et précautions)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

…Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

…1: Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Other drugs: Amiodarone Amiodarone inhibits peripheral conversion of levothyroxine (T4) to triiodothyronine (T3) and may cause isolated biochemical changes (increase in serum free-T4, and decreased or normal free-T3) in clinically euthyroid patients. (notice Liothyronine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

• Hypothyroidism and Hyperthyroidism: Monitor thyroid function regularly ( 5.7 ). (notice Lithium, Mises en garde et précautions)

…Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

…Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

An initial increase in serum FT 4 is followed by return of FT 4 to normal levels with sustained therapeutic serum salicylate concentrations, although total T 4 levels may decrease by as much as 30%. (notice Lévothyroxine, Interactions médicamenteuses)

An initial increase in serum FT 4 is followed by return of FT 4 to normal levels with sustained therapeutic serum salicylate concentrations, although total T 4 levels may decrease by as much as 30%. (notice Lévothyroxine, Interactions médicamenteuses)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

…Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Androgens/Anabolic Steroids Asparaginase Glucocorticoids Slow-Release Nictonic Acid These drugs may decrease serum TBG concentration. (notice Lévothyroxine, Interactions médicamenteuses)

Drug or Drug Class Effect Beta-adrenergic antagonists e.g., Propranolol > 160 mg/day) In patients treated with large doses of propranolol (> 160 mg/day), T 3 and T 4 levels change slightly, TSH levels remain normal, and patients are clinically euthyroid. (notice Lévothyroxine, Interactions médicamenteuses)

Drug or Drug Class Effect Beta-adrenergic antagonists e.g., Propranolol > 160 mg/day) In patients treated with large doses of propranolol (> 160 mg/day), T 3 and T 4 levels change slightly, TSH levels remain normal, and patients are clinically euthyroid. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

…Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

…Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Drug or Drug Class Effect Beta-adrenergic antagonists e.g., Propranolol > 160 mg/day) In patients treated with large doses of propranolol (> 160 mg/day), T 3 and T 4 levels change slightly, TSH levels remain normal, and patients are clinically euthyroid. (notice Lévothyroxine, Interactions médicamenteuses)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

…1: Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

…Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

…1: Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

…1: Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

…1: Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Thyroid Function Abnormalities MYCAPSSA suppresses the secretion of thyroid-stimulating hormone, which may result in hypothyroidism. (notice Octréotide, Mises en garde et précautions)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Drug Interactions and Decreased Vitamin Absorption ORLISTAT may interact with concomitant drugs including cyclosporine, levothyroxine, warfarin, amiodarone, antiepileptic drugs, and antiretroviral drugs [see Drug Interactions (7) ]. (notice Orlistat, Mises en garde et précautions)

An initial increase in serum FT 4 is followed by return of FT 4 to normal levels with sustained therapeutic serum salicylate concentrations, although total T 4 levels may decrease by as much as 30%. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Monitoring pituitary function (e.g., thyroid, adrenal, gonadal) prior to initiation of therapy with SIGNIFOR LAR, as well as periodically during treatment, as clinically appropriate, is recommended. (notice Pasiréotide, Mises en garde et précautions)

Hypothyroidism : Monitor thyroid tests at baseline, during treatment and as clinically indicated and manage hypothyroidism as appropriate. (notice Pazopanib, Mises en garde et précautions)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Drug or Drug Class Effect Phenobarbital Rifampin Phenobarbital has been shown to reduce the response to thyroxine. (notice Lévothyroxine, Interactions médicamenteuses)

Drug or Drug Class Effect Phenobarbital Rifampin Phenobarbital has been shown to reduce the response to thyroxine. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Phenytoin and carbamazepine reduce serum protein binding of levothyroxine, and total and free T4 may be reduced by 20% to 40%, but most patients have normal serum TSH levels and are clinically euthyroid. (notice Lévothyroxine, Interactions médicamenteuses)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

…Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Hypothyroidism Adults: Clinical trials with quetiapine demonstrated dose-related decreases in thyroid hormone levels. (notice Quétiapine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Drug or Drug Class Effect Phenobarbital Rifampin Phenobarbital has been shown to reduce the response to thyroxine. (notice Lévothyroxine, Interactions médicamenteuses)

…levonorgestrel Immunosuppressants Cyclosporine, tacrolimus Methylxanthines Theophylline Narcotic analgesics Methadone Phosphodiesterase-5 (PDE-5) Inhibitors Sildenafil Thyroid preparations Levothyroxine Tricyclic antidepressants Amitriptyline, nortriptyline 7.5 Other Interactions The conversion of PRIFTIN to 25-desacetyl rifapentine is mediated by an esterase enzyme. (notice Rifapentine, Interactions médicamenteuses)

Oral Anticoagulants Levothyroxine increases the response to oral anticoagulant therapy. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

An initial increase in serum FT 4 is followed by return of FT 4 to normal levels with sustained therapeutic serum salicylate concentrations, although total T 4 levels may decrease by as much as 30%. (notice Lévothyroxine, Interactions médicamenteuses)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Administration of sertraline in patients stabilized on levothyroxine may result in increased levothyroxine requirements. (notice Lévothyroxine, Interactions médicamenteuses)

For oral medication where a reduction in the bioavailability of that medication would have a clinically significant effect on its safety or efficacy (e.g., cyclosporine, tacrolimus, levothyroxine), consider separation of the timing of the administration of the two drugs [see Clinical Pharmacology (12.3) ] . (notice Sévélamer, Interactions médicamenteuses)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Worsening of Diabetic Control : May worsen glycemic control and result in increased antidiabetic agent or insulin requirements. (notice Lévothyroxine, Mises en garde et précautions)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Hypothyroidism: Monitor thyroid function periodically as hypothyroidism may occur or worsen after initiation of somatropin. (notice Somatropine, Mises en garde et précautions)

• Impairment of Thyroid Stimulating Hormone Suppression (TSH) in DTC : Monitor TSH monthly and adjust thyroid replacement therapy in patients with thyroid cancer. (notice Sorafénib, Mises en garde et précautions)

An initial increase in serum FT 4 is followed by return of FT 4 to normal levels with sustained therapeutic serum salicylate concentrations, although total T 4 levels may decrease by as much as 30%. (notice Lévothyroxine, Interactions médicamenteuses)

An initial increase in serum FT 4 is followed by return of FT 4 to normal levels with sustained therapeutic serum salicylate concentrations, although total T 4 levels may decrease by as much as 30%. (notice Lévothyroxine, Interactions médicamenteuses)

• Thyroid Dysfunction : Monitor thyroid function at baseline, periodically during treatment, and as clinically indicated. (notice Sunitinib, Mises en garde et précautions)

…Drugs That May Alter T 4 and Triiodothyronine (T 3 ) Serum Transport Without Effecting Free Thyroxine (FT 4 ) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Androgens/Anabolic Steroids Asparaginase Glucocorticoids Slow-Release Nictonic Acid These drugs may decrease serum TBG concentration. (notice Lévothyroxine, Interactions médicamenteuses)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. (notice Lévothyroxine, Mises en garde et précautions)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Sympathomimetics Concurrent use may of sympathomimetics and levothyroxine may increase the effects of sympathomimetics or thyroid hormone. (notice Lévothyroxine, Interactions médicamenteuses)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. (notice Lévothyroxine, Interactions médicamenteuses)

Oral Anticoagulants Levothyroxine increases the response to oral anticoagulant therapy. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Effect on Ketone and Thyroid Function Tests Valproate is partially eliminated in the urine as a keto-metabolite which may lead to a false interpretation of the urine ketone test. (notice Acide valproïque, Mises en garde et précautions)

Hypocalcemia and Mineral Metabolism Preexisting hypocalcemia and disturbances of mineral metabolism (e.g., hypoparathyroidism, thyroid surgery, parathyroid surgery; malabsorption syndromes, excision of small intestine) must be effectively treated before initiating therapy with Reclast. (notice Acide zolédronique, Mises en garde et précautions)

Cytologic abnormalities characterized by giant, hyperchromatic nuclei have been reported in lymph nodes, pancreas, thyroid, adrenal glands, liver, and bone marrow. (notice Busulfan, Mises en garde)

Changes in thyroid status may occur if barbiturates are added or withdrawn from patients being treated for hypothyroidism. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Secondary malignancies (urinary tract cancer, myelodysplasia, acute leukemias, lymphomas, thyroid cancer, and sarcomas) have been reported in patients treated with cyclophosphamide-containing regimens . (notice Cyclophosphamide, Mises en garde et précautions)

Losartan, glipizide and levothyroxine did not show any changes in exposure when co-administered with LOKELMA. (notice Cyclosilicate de zirconium sodique, Interactions médicamenteuses)

Other Medications Used for the Management of Fanconi Syndrome PROCYSBI can be administered with other electrolyte and mineral replacements necessary for management of Fanconi syndrome, as well as vitamin D and thyroid hormone. (notice Cystéamine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Effect on Ketone and Thyroid Function Tests Valproate is partially eliminated in the urine as a keto-metabolite which may lead to a false interpretation of the urine ketone test. (notice Divalproate de sodium (valproate), Mises en garde et précautions)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Cases of myelodysplastic syndrome, acute leukemias, lymphomas, thyroid cancers, and sarcomas have occurred and may develop several years after chemotherapy has been discontinued. (notice Ifosfamide, Mises en garde et précautions)

Hypothyroidism has been reported in thyroidectomy patients undergoing levothyroxine replacement. (notice Imatinib, Mises en garde et précautions)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Warnings Potassium iodide can cause fetal harm, abnormal thyroid function, and goiter when administered to a pregnant woman. (notice Iodure de potassium, Mises en garde)

Ketamine Concurrent use of ketamine and levothyroxine may produce marked hypertension and tachycardia. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Thyroid Disorders Both hypothyroidism and hyperthyroidism have been reported [see Adverse Reactions (6.2) ] . (notice Lénalidomide, Mises en garde et précautions)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Changes in thyroid status may occur if barbiturates are added or withdrawn from patients being treated for hypothyroidism. (notice Lévothyroxine, Interactions médicamenteuses)

EMROSI may induce hyperpigmentation in many organs, including nails, bone, skin, eyes, thyroid, visceral tissue, oral cavity (teeth, mucosa, alveolar bone), sclerae and heart valves. (notice Minocycline, Mises en garde et précautions)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

…performed, the following concomitant drugs were used in at least 10% of patients in either or both Sjogren's efficacy studies: acetylsalicylic acid, artificial tears, calcium, conjugated estrogens, hydroxychloroquine sulfate, ibuprofen, levothyroxine sodium, medroxyprogesterone acetate, methotrexate, multivitamins, naproxen, omeprazole, paracetamol, and prednisone. (notice Pilocarpine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Changes in thyroid status may occur if barbiturates are added or withdrawn from patients being treated for hypothyroidism. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-Inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. (notice Lévothyroxine, Interactions médicamenteuses)

…adjustment is needed when SINGULAIR is co-administered with theophylline, prednisone, prednisolone, oral contraceptives, fexofenadine, digoxin, warfarin, gemfibrozil, itraconazole, thyroid hormones, sedative hypnotics, non-steroidal anti-inflammatory agents, benzodiazepines, decongestants, and Cytochrome P450 (CYP) enzyme inducers [see Clinical Pharmacology (12.3)… (notice Montélukast, Interactions médicamenteuses)