As a clinical pharmacist, you should focus on common and serious drug interactions. Dosing and drug interactions with colchicine for acute gout are still causing confusion. We're all used to the old way of dosing colchicine for acute gout, two tabs initially then one tab every 2 hours until the pain stops, diarrhea starts, or a max of 5 tabs per day. But this can cause too much toxicity, and even some deaths.
Recommend the newer, safer dosing. The new dosing for a gout flare is two 0.6 mg or 0.5 mg tablets followed by just ONE tab an hour later. Recommend even lower and less frequent dosing if colchicine is used with other drugs that inhibit its metabolism. Recommend just one tab per attack with cyclosporine, one tab followed by a half tab with strong 3A4 inhibitors (clarithromycin, etc) and two tabs with moderate 3A4 inhibitors (verapamil, etc). Tell patients not to repeat these colchicine doses for at least 3 days.
For severe renal or hepatic impairment, recommend a 3-tablet course, but wait at least 2 weeks before repeating the course. Avoid colchicine plus cyclosporine or a strong 3A4 inhibitor if patients have renal or hepatic impairment. This can be fatal. Continue to recommend NSAIDs or corticosteroids first-line for acute gout. They're usually better tolerated. If needed, get our notes, "Comparison of gout therapies", for more information.
| Table (1). Drug Interactions with Colchicine | ||
|---|---|---|
| Typical Agents | Mechanism | Clinical Management |
| CYP3A4/5, P-glycoprotein inducers | Increased colchicine metabolism or transport reduces colchicine effectiveness | Monitor and consider dose increases of colchicine |
| CYP3A4/5, P-glycoprotein inhibitors | Decreased colchicine metabolism or transport increases risk of colchicine toxicity | Monitor and consider dose decreases of colchicine, particularly if renal or hepatic dysfunction exists |
| Lipid-lowering agents (fibrates, statins) | Coadministration of colchicine and lipid-lowering agents may result in myopathy and rhabdomyolysis; mechanism unknown | Avoid concurrent use |
REFERENCES
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Terkeltaub RA, Furst DE, Digiacinto JL, Kook KA, Davis MW. Novel evidence-based colchicine dose-reduction algorithm to predict and prevent colchicine toxicity in the presence of cytochrome P450 3A4/P-glycoprotein inhibitors. Arthritis Rheum. 2011 Aug;63(8):2226-37. Available at: https://onlinelibrary.wiley.com/doi/epdf/10.1002/art.30389
Kolesar, J. M., & Vermeulen, L. C. (2022). McGraw Hill’s 2021/2022 Top 300 Pharmacy Drug Cards. McGraw Hill Professional. Available at: https://accesspharmacy.mhmedical.com/qa.aspx?groupid=955 [Need Access]
Venturini CD, Engroff P, Ely LS, Zago LF, Schroeter G, Gomes I, De Carli GA, Morrone FB. Gender differences, polypharmacy, and potential pharmacological interactions in the elderly. Clinics (Sao Paulo). 2011;66(11):1867-72. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3203957