INFORMATION FOR HEALTH PROFESSIONALS
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Web site: December 1998
Prescriber Update No.17:9-11
Medsafe Editorial Team
The maximum dose of colchicine in an acute attack of gout should be 6mg (10 tablets). Colchicine should be taken at an initial dose of 1.2mg followed by 1 tablet every 2 hours until the gouty pain is relieved, gastrointestinal symptoms develop, or the maximum dose is reached. In elderly patients, those who weigh less than 50kg and those with co-existing renal or hepatic disease, alternative therapy should be used or a maximum dose of 3mg colchicine observed. Patients with suspected overdose should be admitted to a hospital with intensive supportive facilities.
The dosage instructions for colchicine have recently been changed to reflect the fact that it is possible to take a fatal dose before gaining relief from the symptoms of gout or developing diarrhoea.
6mg maximum dose in acute gout
3mg maximum dose for at risk patients
Intensive regimen should not be repeated for 3 days
Dose reduction based on published evidence of toxicity
Steroids recommended for colchicine therapeutic failures
Co-administration of NSAIAs with colchicine should be avoided
Hospitalisation essential for suspected overdose
References
The approved dosage instructions for colchicine in the treatment of acute gout now recommend a starting dose of 1.2mg (two 0.6mg tablets), followed by 1 tablet 2-hourly until the pain is relieved or diarrhoea or other gastrointestinal symptoms develop, up to a maximum dose of 6mg (10 tablets).
In elderly patients, those who weigh less than 50kg and those with renal or hepatic impairment, other treatments such as a non-steroidal anti-inflammatory agent (NSAIA) or high dose (20-40mg) short duration oral prednisone or prednisolone should be considered. If colchicine is prescribed for these patients the maximum total dose should be 3mg.
An intensive regimen of colchicine therapy should not be repeated until an interval of at least three days has elapsed between courses. Nevertheless, maintenance therapy of one tablet daily may be commenced the day following treatment for an acute attack.
The two major changes in the dosage instructions relate to frequency of administration and maximum dose.
Previously no maximum was stated in the approved dosage instructions. The maximum recommended dose has been set by reference to the following:
The recommended frequency of administration has been halved, to further reduce the chance of serious toxicity occurring. The new frequency is similar to that recommended in Australia and the United Kingdom.
For a patient who has not gained adequate pain relief from the maximum dose of colchicine, alternatives are intramuscular corticotrophin 40-80IU or oral prednisone 20-50 mg/day for 3 days.1
While either a NSAIA or colchicine can be used as first line therapy for acute gout, they should not be co-prescribed as both medicines compete for excretion at the same site in the kidney. In addition to competition for excretion, use of NSAIAs is associated with decreased renal blood flow. Increased colchicine toxicity, due to delayed renal excretion, is the end result of these pharmacodynamic effects.
If there is a high probability of colchicine toxicity, for example because of intentional overdose or dose in excess of 6mg in high risk patients, prompt admission to a facility with access to intensive supportive treatment is essential.
In overdose, early use of activated charcoal will minimise absorption. Repeated doses of charcoal will assist with the elimination of colchicine reabsorbed into the intestines through enterohepatic recycling. Diarrhoea should not be treated as it is the primary route of elimination. The period 24-72 hours after ingestion is critical and multisystem organ failure may occur. The key to patient management is full supportive care.
Serious toxicity with colchicine is an adverse reaction of current concern. Please report all New Zealand cases to the New Zealand Centre for Adverse Reactions Monitoring.