New algorithm may help to prevent colchicine toxicity in gout patients
Published on 02 December 2011
Scientists have developed a new algorithm that could help to avoid drug toxicity in gout
patients who use colchicine.
The therapy is often taken at the start of a gout attack, as it can help to damp down the inflammation cause by urate crystals in the lining of the joints.
However, the drug can cause problems when taken at the same time as certain other therapies, as they may interact and cause harm.
A new study in the journal Arthritis & Rheumatism looked at the problem of colchicine toxicity in the presence of drugs called cytochrome P450 3A4/P-glycoprotein inhibitors.
A total of seven separate studies were performed to determine the effects of treatment with both colchicine and these other drugs - cyclosporine, ketoconazole, ritonavir, clarithromycin, azithromycin, verapamil ER [extended release]), and diltiazem ER.
The researchers, who were based at the University of California, San Diego, found there were significant drug-drug interactions when single doses of colchicine were administered at the same time as most of the other drugs.
They calculated that the dose of colchicine should be reduced by 33 to 66 per cent for the treatment of acute gout when administered alongside any of the other drugs, with the exception of azithromycin, for which no dose adjustment is required.
"These studies provide quantitative evidence regarding drug interactions and necessary adjustments in the dose of colchicine if colchicine treatment is continued during therapy with multiple CYP3A4/P-glycoprotein inhibitors," the study authors concluded.
Dr Max Hamburger, president of the New York State Rheumatology Society, who was not involved with the research, told Pain Medicine News that the information provided by the study was "very important" and should be made available to primary care doctors.
"Gout is one of the most painful experiences that one can have...," he noted.
"This article gave us a basis for adjusting the dose and therefore being able to treat the patient safely."
A spokeswoman for Arthritis Research UK, which is carrying out research into improving the way that gout is treated in primary care, welcomed the findings as being potentially beneficial to patients.