Interaction entre Ergotamine et caféine et Isoniazide

WARNING Serious and/or life-threatening peripheral ischemia has been associated with the coadministration of ergotamine tartrate and caffeine tablets with potent CYP 3A4 inhibitors including protease inhibitors and macrolide antibiotics.

CONTRAINDICATIONS Coadministration of ergotamine with potent CYP 3A4 inhibitors (ritonavir, nelfinavir, indinavir, erythromycin, clarithromycin, and troleandomycin) has been associated with acute ergot toxicity (ergotism) characterized by vasospasm and ischemia of the extremities (see PRECAUTIONS : Drug Interactions ), with some cases resulting in amputation.

Because of the increased risk of ergotism and other serious vasospastic adverse events, ergotamine use is contraindicated with these drugs and other potent inhibitors of CYP 3A4 (e.g., ketoconazole, itraconazole) (see WARNINGS : CYP 3A4 Inhibitors ).

While these reactions have not been reported with less potent CYP 3A4 inhibitors, there is a potential risk for serious toxicity including vasospasm when these drugs are used with ergotamine.

WARNINGS - CYP 3A4 Inhibitors (e.g. Macrolide Antibiotics and Protease Inhibitors) Coadministration of ergotamine with potent CYP 3A4 inhibitors such as protease inhibitors or macrolide antibiotics has been associated with serious adverse events; for this reason, these drugs should not be given concomitantly with ergotamine (See CONTRAINDICATIONS ) .

Theophylline A recent study has shown that concomitant administration of isoniazid and theophylline may cause elevated plasma levels of theophylline, and in some instances a slight decrease in the elimination of isoniazid.

Since the therapeutic range of theophylline is narrow, theophylline serum levels should be monitored closely, and appropriate dosage adjustments of theophylline should be made 7 .