Prescriber Update 26(2): 26–27
Medsafe Pharmacovigilance Team
The dosage advice for colchicine has been revised, coinciding with the introduction of a 0.5mg strength tablet. Colchicine is now indicated as second-line therapy for acute gout. For healthy adults the dosing interval has been increased to six hourly, with a maximum dose of 2.5mg in the first 24 hours and a maximum cumulative dose of 6mg over four days. In elderly patients, patients with renal or hepatic impairment, and patients weighing less than 50kg other treatments should be considered or lower doses of colchicine used. Patients should be warned of the symptoms of colchicine toxicity and advised to discontinue therapy immediately if they occur.
A new 0.5mg strength of colchicine tablets is now available in New Zealand, under the brand name of Colgout®, with revised dosage advice.1 While colchicine is effective for treating acute gout it has a slow onset of action, with limited effectiveness if treatment is delayed and a narrow therapeutic index.2 Due to the risk of dose-related serious adverse effects the use of high doses of colchicine to treat acute gout is no longer appropriate, especially in elderly patients,3 patients with impaired hepatic or renal function,1 and patients who weigh less than 50kg.4
Colchicine is now indicated as second-line therapy in the treatment of acute gout. Colchicine should not be used unless non-steroidal anti-inflammatories are contraindicated, or have been used and found to lack analgesic efficacy or to have unacceptable side effects in the individual patient.1
The dosing interval for colchicine has been increased from 2-3 hourly to six hourly. The dose for otherwise healthy adults is 1mg initially, then 0.5mg every six hours until pain relief is obtained.1 From a safety perspective, it is no longer acceptable to continue dosing until gastrointestinal adverse effects occur.
For otherwise healthy adults the maximum dose of colchicine in the first 24 hours is 2.5mg and the total dose given in an acute attack should not exceed 6mg over four days.1
The elderly may be more susceptible to cumulative toxicity with colchicine,5 and due to age-related renal function impairment, other treatments such as corticosteroids should be considered. If colchicine is used in the elderly lower doses should be given and a maximum cumulative dose of 3mg over four days should be observed.1
Colchicine is contraindicated in severe renal impairment (creatinine clearance <10ml/min1) or hepatic impairment, and concomitant renal and hepatic disease. If colchicine is used in patients with less severe impairment a reduction in the individual doses, an increase in the interval between doses or a reduction in the total daily dose may be necessary. Specifically, the dose should be reduced by half if the patient's creatinine clearance is 50ml/min or less; and close monitoring is advised.1
Prescribers are reminded that for all patients at least three days must elapse between courses of acute treatment with colchicine, in order to avoid the risk of toxicity due to colchicine accumulation.1
Colchicine in overdose is extremely toxic and has resulted in fatalities.6 Patients should be warned that the first signs of toxicity are nausea, vomiting and diarrhoea. A burning sensation of the throat, stomach or skin may also occur. Symptoms usually appear 2 to 12 hours post-ingestion and often before pain relief is obtained.5 If symptoms of toxicity occur patients should immediately discontinue colchicine therapy and see their doctor. If toxicity is suspected, prompt hospital admission is essential.4
This revised dosage advice is consistent with that issued in the New Zealand Rheumatology Association's 2005 Consensus Statement on the Use of Colchicine in the Treatment of Gout .3
Competing interests (authors): none declared.