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Interacting Drugs

OBJECT DRUGS

PRECIPITANT DRUGS

Inhibitors of CYP3A4 and P-glycoprotein:


Comment:

Colchicine is a substrate for CYP3A4 and P-glycoprotein (P-gp) and concurrent use of CYP3A4 and P-gp inhibitors has resulted in severe colchicine toxicity, including gastrointestinal toxicity, rhabdomyolysis, pancytopenia, and multi-organ failure. Colchicine toxicity is difficult to treat, and fatalities have been reported, especially if the patient has renal impairment. Most of the inhibitors listed above inhibit both CYP3A4 and P-gp, and it has not been established that drugs inhibiting only one or the other would increase colchicine plasma levels. For example, propafenone inhibits P-gp but may not have much effect on CYP3A4, so it is possible that it is less likely to interact with colchicine than drugs that inhibit both. Although grapefruit inhibits CYP3A4 and colchicine toxicity has been reported with large amounts of grapefruit juice, one study failed to find an effect of grapefruit juice on colchicine.


Class 2: Use Only if Benefit Felt to Outweigh Risk