Vitamin K interactions

WARNING: SERIOUS ADVERSE REACTIONS OR DEATH IN PATIENTS WITH COMPLETE DPD DEFICIENCY and INCREASED RISK OF BLEEDING WITH CONCOMITANT USE OF VITAMIN K ANTAGONISTS Increased risk of serious adverse reactions or death in patients with complete DPD deficiency • Test patients for genetic variants of DPYD prior to initiating XELODA unless immediate treatment is necessary. (Capecitabine label, Boxed warning)

Do not administer agents that enhance the risk of hemorrhage with fondaparinux sodium unless essential for the management of the underlying condition, such as vitamin K antagonists for the treatment of VTE. (Fondaparinux label, Warnings and precautions)

A potentially life-threatening bleeding disorder related to decreased levels of vitamin K-dependent clotting factors may occur in newborns exposed to phenytoin in utero. (Phenytoin label, Warnings and precautions)

Postmarketing reports suggest that concomitant administration of high doses of cefazolin and rifampin may prolong the prothrombin time, leading to severe vitamin K–dependent coagulation disorders that may be life-threatening or fatal. (Rifampin label, Warnings)

Vitamin K reduces the anticoagulant effect of warfarin; sudden changes in intake from supplements or diet can throw off INR. (NIH Office of Dietary Supplements, Vitamin K)

For patients with APS (especially those who are triple positive [positive for lupus anticoagulant, anticardiolipin, and anti-beta 2-glycoprotein I antibodies]), treatment with DOACs has been associated with increased rates of recurrent thrombotic events compared with vitamin K antagonist therapy. (Apixaban label, Warnings and precautions)

Prothrombin time should be monitored in patients at risk and exogenous vitamin K administered as indicated. (Cefixime label, Warnings and precautions)

Vitamin K or Fat-Soluble Vitamin Deficiencies: Colesevelam hydrochloride may decrease absorption of fat-soluble vitamins. (Colesevelam label, Warnings and precautions)

For patients with APS (especially those who are triple-positive [positive for lupus anticoagulant, anticardiolipin, and anti-beta 2-glycoprotein I antibodies]), treatment with DOACs has been associated with increased rates of recurrent thrombotic events compared with vitamin K antagonist therapy. (Dabigatran label, Warnings and precautions)

For patients with APS (especially those who are triple positive [positive for lupus anticoagulant, anticardiolipin antibodies, and anti-beta 2-glycoprotein I antibodies]), treatment with DOACs has been associated with increased rates of recurrent thrombotic events compared with vitamin K antagonist therapy. (Edoxaban label, Warnings and precautions)

Drug Interactions Anticoagulants (oral): Due to potential inhibition of vitamin K activity by methimazole, the activity of oral anticoagulants (e.g., warfarin) may be increased; additional monitoring of PT/INR should be considered, especially before surgical procedures. β-adrenergic blocking agents: Hyperthyroidism may cause an increased clearance of beta blockers… (Methimazole label, Drug interactions)

Oral neomycin sulfate may enhance the effect of coumarin in anticoagulants by decreasing vitamin K availability. (Neomycin label, Drug interactions)

The effect of ORLISTAT on the absorption of supplemental vitamin D, vitamin A, and nutritionally-derived vitamin K is not known at this time [see Clinical Pharmacology (12.3) , and Warnings and Precautions (5.1) ] . (Orlistat label, Drug interactions)

Increased prothrombin time has been reported in patients concomitantly treated with pentoxifylline and vitamin K antagonists. (Pentoxifylline label, Drug interactions)

Drug Interactions Anticoagulants (oral): Due to the potential inhibition of vitamin K activity by propylthiouracil, the activity of oral anticoagulants (e.g., warfarin) may be increased; additional monitoring of PT/INR should be considered, especially before surgical procedures. (Propylthiouracil label, Drug interactions)

For patients with APS (especially those who are triple positive [positive for lupus anticoagulant, anticardiolipin, and anti-beta 2-glycoprotein I antibodies]), treatment with DOACs has been associated with increased rates of recurrent thrombotic events compared with vitamin K antagonist therapy. (Rivaroxaban label, Warnings and precautions)

Oral Vitamin K Antagonist Anticoagulants Changes in anticoagulant activity may be seen with androgens; therefore, more frequent monitoring of international normalized ratio (INR) and prothrombin time are recommended in patients taking warfarin, especially at the initiation and termination of androgen therapy. (Testosterone label, Drug interactions)

Cutaneous Reactions Parenteral administration of vitamin K replacements (including phytonadione injectable emulsion) may cause cutaneous reactions. (Phytonadione (vitamin K1) label, Warnings and precautions)

Neonatal hemorrhage, with a coagulation defect resembling vitamin K deficiency, has been described in newborns whose mothers were taking primidone and other anticonvulsants. (Primidone label, Warnings)