RiteMED Colchicine Drug Interactions

Colchicine is a substrate for both CYP3A4 and the transport protein P-gp. In the presence of CYP3A4 or P-gp inhibitors, the concentrations of colchicine in the blood increase. Toxicity, including fatal cases, have been reported during concurrent use of CYP3A4 or P-gp inhibitors such as macrolides (clarithromycin and erythromycin), ciclosporin, ketoconazole, itraconazole, voriconazole, HIV protease inhibitors, calcium channel blockers (verapamil and diltiazem) and disulfiram.
Concomitant administration of azithromycin and P-gp substrates such as colchicine has been reported to result in increased serum levels of P-gp substrate. Therefore, if colchicine and azithromycin are administered concomitantly, the possibility of elevated serum colchicine concentrations should be considered.
Colchicine is contraindicated in patients with renal or hepatic impairment who are taking a P-gp inhibitor (e.g., ciclosporin, verapamil or quinidine) or a strong CYP3A4 inhibitor (e.g., ritonavir, atazanavir, indinavir, clarithromycin, telithromycin, itraconazole or ketoconazole).
A reduction in colchicine dosage or an interruption of colchicine treatment is recommended in patients with normal renal or hepatic function if treatment with a P-gp inhibitor or moderate or strong CYP3A4 inhibitor is required. A 4-fold reduction in colchicine dosage is recommended when co-administered with a P-gp inhibitor and/or a strong CYP3A4 inhibitor. A 2-fold reduction in colchicine dosage is recommended when co-administered with a moderate CYP3A4 inhibitor.