Ciprofloxacin × Colchicine

Colchicine is cleared through the CYP3A4 enzyme and the P-glycoprotein transporter and has a narrow therapeutic margin (colchicine SmPC). Ciprofloxacin's own labels describe it as a CYP1A2 inhibitor, while the US Food and Drug Administration (FDA) also lists it as a moderate CYP3A4 inhibitor. CYP3A4 inhibition can raise colchicine blood levels and, with them, the risk of toxicity.

Nausea, vomiting, diarrhoea, muscle weakness, paraesthesias. With severe toxicity: myopathy, neuropathy, bone marrow suppression.

The combination is contraindicated by the Spanish colchicine SmPC, which forbids colchicine during use of CYP3A4 or P-glycoprotein inhibitors and for 14 days afterwards (colchicine SmPC). The US Food and Drug Administration (FDA) classifies ciprofloxacin as a moderate CYP3A4 inhibitor (FDA list), so colchicine is not given during a ciprofloxacin course or for 14 days after it. Other colchicine manufacturers require a lower maximum colchicine dose and close monitoring with a moderate CYP3A4 inhibitor (colchicine SmPC), and the US label of colchicine for cardiovascular prevention advises avoiding such drugs in renal or hepatic impairment (colchicine label, FDA). Colchicine itself is contraindicated in severe renal or hepatic impairment (colchicine SmPC). At the first sign of nausea, vomiting, abdominal pain or diarrhoea, colchicine is stopped and the patient needs urgent care (colchicine SmPC).