Colchicine

Colchicine is an alkaloid derived from the autumn crocus plant (Colchicum autumnale) that has been used medicinally for thousands of years, primarily for the treatment of gout. Today, it is used in modern medicine for three principal indications: acute gouty arthritis, familial Mediterranean fever (FMF), and pericarditis (inflammation of the membrane surrounding the heart). Colchicine 500 mcg tablets are the standard formulation available in the UK.

Treatment of Acute Gout

In acute gout, colchicine is one of the first-line analgesic and anti-inflammatory options, alongside non-steroidal anti-inflammatory drugs (NSAIDs) and corticosteroids. It is particularly valuable in patients where NSAIDs are contraindicated - such as those on anticoagulants, with peptic ulcer disease, or with renal impairment - provided the colchicine dose is adjusted appropriately. Colchicine must be started as early as possible after the onset of acute gout symptoms to be most effective; ideally within the first 12 to 24 hours. It does not lower uric acid levels and should not be confused with urate-lowering therapy such as allopurinol or febuxostat.

Familial Mediterranean Fever

FMF is a hereditary autoinflammatory disease characterised by recurrent episodes of fever, serositis (peritonitis, pleuritis, pericarditis), and arthritis. Long-term colchicine treatment at low to moderate doses significantly reduces the frequency and severity of these episodes and, critically, prevents the development of secondary amyloidosis, a serious long-term complication of untreated FMF.

Pericarditis

Colchicine is now a cornerstone of treatment for acute pericarditis, both in the initial episode and for recurrent disease. Used alongside aspirin or NSAIDs, it significantly reduces the rate of recurrence and shortens the duration of symptoms. Its anti-inflammatory mechanism is distinct from that of NSAIDs, making it a complementary rather than alternative therapy.

Narrow Therapeutic Index

Colchicine has a narrow therapeutic index, meaning the difference between an effective dose and a toxic dose is small. Adherence to prescribed doses and awareness of drug interactions are essential to avoid serious toxicity.

Treating an Acute Gout Attack

Start colchicine as early as possible at the first sign of an attack, ideally within 12 to 24 hours of symptoms beginning. The later it is started, the less effective it tends to be. Current UK guidance recommends 500 mcg two to four times daily until symptoms resolve or until side effects (particularly diarrhoea) become limiting. The maximum course dose is 6 mg. A shorter course of 500 mcg twice or three times daily for two to three days is often preferred over higher doses, as it is better tolerated.

Gout Prevention

For long-term gout prevention, lower doses of 500 mcg once or twice daily are used, usually for several months when starting urate-lowering therapy such as allopurinol. This prevents the acute attacks that often flare up when uric acid levels begin to fall. Take with or after food if stomach upset is a problem.

Acute gout: 500 mcg two to four times daily until relief is achieved or gastrointestinal side effects prevent further use. Total maximum dose per course: 6 mg (12 tablets). Do not repeat the course within 3 days.

Familial Mediterranean fever:

• Adults: 1 to 2 mg daily, given as a single dose or in two divided doses
• Children 5 to 12 years: 0.5 to 1 mg daily
• Children under 5 years: 0.5 mg daily

Acute pericarditis (in combination with aspirin or NSAIDs):

• Adults over 70 kg: 500 mcg twice daily for 3 months
• Adults under 70 kg or who are intolerant of higher doses: 500 mcg once daily for 3 months

Renal impairment: Dose reduction is mandatory in moderate renal impairment (eGFR 30-60 mL/min/1.73m2) and colchicine is generally contraindicated in severe renal impairment. Specialist guidance should be followed.

Hepatic impairment: Use with caution; dose reduction required in significant hepatic disease.

Elderly patients: Use with caution and at the lower end of the dose range, given increased sensitivity to side effects.

Common Side Effects

Gastrointestinal side effects are the most common with colchicine and are dose-dependent. They can also be an early sign of toxicity:

• Diarrhoea (the most common, and often dose-limiting)
• Nausea and vomiting
• Abdominal cramping and discomfort

Serious Toxicity

Colchicine has a narrow therapeutic window, meaning the gap between an effective dose and a toxic dose is relatively small. At higher doses or in overdose, it can cause severe gastrointestinal damage, bone marrow suppression, muscle breakdown (myopathy), and multi-organ failure. Do not take more than prescribed. Colchicine can interact seriously with certain medicines including statins, ciclosporin, and some antibiotics — tell your doctor about all medicines you are taking. Dose reduction is needed in kidney or liver impairment.

Drug Interactions and CYP3A4

Colchicine has clinically important and potentially dangerous interactions with several commonly prescribed medicines. CYP3A4 inhibitors - including clarithromycin, erythromycin, ritonavir, ciclosporin, itraconazole, and ketoconazole - substantially increase colchicine plasma concentrations and can precipitate life-threatening toxicity even at standard doses. Colchicine doses must be reduced significantly or avoided entirely when these medicines are used concurrently. Similarly, P-glycoprotein inhibitors such as verapamil can increase colchicine levels. Statins, when used alongside colchicine, increase the risk of myopathy and rhabdomyolysis, particularly in patients with renal impairment. Prescribers and patients should always check for interactions before adding any new medication.

Renal and Hepatic Impairment

Colchicine is primarily eliminated via the liver and kidneys, and impairment of either organ significantly increases the risk of accumulation and toxicity. Colchicine is contraindicated in severe renal impairment and in significant hepatic impairment when both organs are simultaneously affected, as dual impairment dramatically increases the risk of toxicity. Even in moderate single-organ impairment, dose reduction is mandatory and patients should be monitored carefully. Elderly patients and those with cardiac failure or low muscle mass are at particular risk of myotoxicity. Women of childbearing age must use effective contraception during colchicine therapy, as it is potentially teratogenic (interferes with mitosis) and has adverse effects on spermatogenesis.

Colchicine is contraindicated or requires very close specialist supervision in the following situations:

• Severe renal impairment (eGFR below 10 mL/min/1.73m2) or patients on dialysis
• Severe hepatic impairment
• Concurrent significant renal AND hepatic impairment (any degree)
• Concurrent use with clarithromycin, ritonavir, ciclosporin, or other potent CYP3A4 and P-glycoprotein inhibitors without substantial dose reduction
• Known hypersensitivity to colchicine or any excipient
• Pregnancy - teratogenic potential due to anti-mitotic mechanism
• Breastfeeding is not recommended at higher doses
• Blood dyscrasias or known bone marrow suppression
• Caution in elderly patients and those with cardiac disease