Colchicine

What it is

Colchicine binds tubulin and disrupts the microtubules that white blood cells need in order to move and pile into an inflamed joint. That interruption of the inflammatory response is what quietens a gout attack and what prevents flares while urate-lowering treatment is being established. It does not lower uric acid itself.

A usual adult range, not a national label — the dose and the timing differ by country and by product.

Used for

• Gout

Approved uses differ by country — some of these may be off-label or unapproved where you live.

What to know while taking it

Colchicine has a narrow safety window, meaning the gap between an effective amount and a toxic one is small, so anything that raises its blood level matters. Grapefruit is avoided, and clarithromycin and atorvastatin both interfere with its clearance, the statin combination also raising the risk of muscle injury. White cells are monitored because colchicine can suppress the marrow, creatinine because impaired kidneys let the drug accumulate, and vitamin B12 because absorption in the gut is blocked with prolonged use.

When to see a doctor

Diarrhoea is the first sign of too much colchicine and is a reason to stop and call a doctor rather than push on. Vomiting, unexplained muscle pain or weakness, numbness or tingling, or fever and sore throat suggesting a low white cell count all mean see a doctor.

Worth knowing

• Avoid grapefruit
• Narrow safety window
• Stop and call a doctor if diarrhoea starts

Markers to watch

• White blood cells
• Creatinine
• Vitamin B12

Nutrients affected

• vitaminB12 — absorption blocked with (Hemoglobin, Homocysteine, Mean cell volume (MCV))