Colchicine

How it works

It binds tubulin and inhibits microtubule polymerisation, impairing neutrophil chemotaxis, activation and the inflammatory response to urate crystals.

Prescribing in practice

• Colchicine has a narrow therapeutic margin, and toxicity (severe diarrhoea, vomiting, myelosuppression and neuromyopathy) is more likely in older patients and in renal or hepatic impairment, so dose conservatively and reduce in impairment.
• It interacts dangerously with strong CYP3A4 and P-glycoprotein inhibitors (such as clarithromycin, certain antifungals and ciclosporin), which can precipitate life-threatening toxicity; avoid or markedly adjust.
• Combining with statins or fibrates increases the risk of myopathy, and gastrointestinal side effects often limit the tolerated dose.

Monitoring

Monitor renal and hepatic function and, with prolonged use, the full blood count, and review promptly if diarrhoea, vomiting or muscle symptoms develop.

Counselling the patient

• Stop the medicine and seek advice if you develop significant diarrhoea, vomiting, unusual bruising or muscle weakness.
• Avoid grapefruit juice and tell clinicians before starting any new medicine, especially certain antibiotics or antifungals.
• Do not take more than prescribed, as excess is dangerous.

Evidence & guidelines

Use in acute and prophylactic gout and the importance of dose limitation in renal impairment and interacting drugs are reflected in NICE and British Society for Rheumatology gout guidance.