Singapore Drugs Database

Indication

For treatment and relief of pain in attacks of acute gouty arthritis.

Mechanism of Action

The precise mechanism of action has not been completely established. In patients with gout, colchicine apparently interrupts the cycle of monosodium urate crystal deposition in joint tissues and the resultant inflammatory response that initiates and sustains an acute attack. Colchicine decreases leukocyte chemotaxis and phagocytosis and inhibits the formation and release of a chemotactic glycoprotein that is produced during phagocytosis of urate crystals. Colchicine also inhibits urate crystal deposition, which is enhanced by a low pH in the tissues, probably by inhibiting oxidation of glucose and subsequent lactic acid production in leukocytes. Colchicine has no analgesic or antihyperuricemic activity. Colchicine inhibits microtubule assembly in various cells, including leukocytes, probably by binding to and interfering with polymerization of the microtubule subunit tubulin. Although some studies have found that this action probably does not contribute significantly to colchicine's antigout action, a recent in vitro study has shown that it may be at least partially involved.

Pharmacokinetics

Absorption

Colchicine is rapidly absorbed after oral administration, probably from the jejunum and ileum. However, the rate and extent of absorption are variable, depending on the tablet dissolution rate; variability in gastric emptying, intestinal motility, and pH at the absorption site; and the extent to which colchicine is bound to microtubules in gastrointestinal mucosal cells.

Distribution

* 5 to 8 L/kg [healthy young volunteers]

Metabolism

Probably hepatic. Although colchicine metabolites have not been identified in humans, metabolism by mammalian hepatic microsomes has been demonstrated in vitro.

Elimination

Clearance

* 0.17 L/hr/kg [familial Mediterranean fever patients with end-stage renal disease] * 0.73 L/hr/kg [familial Mediterranean fever patients with normal renal function]

Toxicity

The onset of toxic effects is usually delayed for several hours or more after the ingestion of an acute overdose. Nausea, vomiting, abdominal pain, and diarrhea occur first. The diarrhea may be bloody due to hemorrhagic gastroenteritis. Burning sensations of the throat, stomach, and skin may be prominent symptoms. Extensive vascular damage may result in shock. Kidney damage, evidenced by hematuria and oliguria, may occur. Muscular weakness may be marked, and ascending paralysis of the central nervous system may develop; the patient usually remains conscious. Delirium and convulsions may occur. Death due to respiratory arrest may result. Although death from the ingestion of as little as 7 mg has been reported, much larger doses have been survived .

Active Ingredient/Synonyms

Colchicin | Colchicina | Colchicinum | Colchicine |