Colchicine

How it works

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

Prescribing in practice

• Colchicine has a narrow therapeutic index and overdose can be fatal — gastrointestinal symptoms such as diarrhoea are an early sign of toxicity and a cue to stop, and accidental or intentional overdose requires urgent specialist help.
• It interacts dangerously with strong CYP3A4 and P-glycoprotein inhibitors (for example clarithromycin, certain antifungals, ciclosporin) and with statins, raising the risk of toxicity and myopathy, so review interacting drugs carefully.
• Reduce dose and frequency in significant renal or hepatic impairment and in older or frail patients, following the SPC.

Monitoring

Monitor for gastrointestinal toxicity, and with prolonged use review full blood count and for muscle or nerve symptoms, especially in renal impairment or with interacting drugs.

Counselling the patient

• Stop taking it and seek advice if you develop diarrhoea, nausea or vomiting, as these can signal toxicity.
• Tell any prescriber you take colchicine before starting new medicines, particularly certain antibiotics or antifungals.
• Never take more than prescribed — taking extra can be dangerous.

Evidence & guidelines

NICE guidance on gout includes colchicine as a treatment option for acute flares, particularly when NSAIDs are unsuitable, using lower doses to limit toxicity.