ColciGel® (Colchicinum 4X) is a substrate of the efflux transporter P-glycoprotein (P-gp). Of the cytochrome P450 enzymes tested, CYP3A4 was mainly involved in the metabolism of colchicinum. If ORAL colchicine is administered with drugs that inhibit P-gp, most of which also inhibit CYP3A4, increased concentrations of colchicinum are likely. Fatal drug interactions have been reported. Topical application of ColciGel® has demonstrated insignificant systemic absorption in animal testing and confirmed in limited human pharmacokinetic eva luations and, therefore, poses a limited risk of clinically significant drug interactions. Physicians should, however, ensure that patients are suitable candidates for treatment with ColciGel® and remain alert for signs and symptoms of toxicities related to increased colchicinum exposure as a result of a drug interaction. Signs and symptoms of ColciGel® toxicity should be eva luated promptly and, if toxicity is suspected, ColciGel® should be discontinued immediately.