Colcrys is a single-ingredient colchicine product, indicated for the prophylaxis and treatment of gout flares, and for the treatment of Familial Mediterranean Fever (FMF).
The studies are intended to support URL Pharma in submitting new drug application (NDA) for Colcrys.
The studies evaluated cyclosporine, an immunosuppressant; clarithromycin and azithromycin, two antibiotics; diltiazem and verapamil, two hypertension drugs; ketoconazole, an anti-fungal drug; and ritonavir, a protease inhibitor.
In the studies, each of these drugs, except for azithromycin, was found to interact with standard colchicine dosing regimens, in some cases more than doubling levels of colchicine in the blood and increasing the risk of serious toxicities.
Cyclosporine and clarithromycin in particular increased peak colchicine blood levels by nearly 300%.
Following the studies, the researchers recommended that colchicine doses be reduced between one-third and two-thirds for acute flares, and by 50 to 75% for flare prophylaxis, when used as concomitant therapy with six of the seven drugs studied.
URL Pharma chief medical officer Matthew Davis said these studies are part of their continued investigation of the pharmacokinetics of colchicine.