Frågedatum: 2001-03-05
RELIS database 2001; id.nr. 16919, DRUGLINE
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Is there any risk of interaction between colchicine and Efexor (venlafaxine), Zoloft (sertraline) o



Fråga: Is there any risk of interaction between colchicine and Efexor (venlafaxine), Zoloft (sertraline) or another SSRI? What kind of interactions can occur? A 56-year-old man with Behcets syndrome has been treated with colchicine for an unknown period of time. He is now suffering from anxiety and treatment with venlafaxine, sertraline or other SSRI:s is considered.

Sammanfattning: There are no known interactions between colchicine and SSRI or venlafaxine. There is a theoretical note of a pharmacokinetic reaction, the significance of which is unknown. Colchicine can interfere with the absorption of other orally administered drugs. Therapeutic drug monitoring of the antidepressant is advisable; the colchicine dose can be titrated based on clinical grounds.

Svar: There is limited information on drug interactions between colchicines and SSRI or venlafaxine in Medline, Embase, Drugline or standard pharmacological literature.

Colchicine can cause diarrhea as an adverse effect that could lead to reduced absorption and consequently reduce plasma drug concentration of other oral drugs (1-2).

Colchicine is partly deacetylated and partly demethylated in the liver and is also slowly metabolised in other tissues (2). Ten to twenty per cent are excreted unchanged in the urine. Large amounts of colchicine and its metabolites undergo enterohepatic circulation that prolongs the clinical effect and accounts for colchicine´s gastrointestinal toxicity (3). Venlafaxine is mainly metabolised by the cytochrome P450 isoenzyme CYP2D6 and to a lesser extent CYP3A4 (4). Sertraline appears to be mainly metabolised by CYP3A4 (5). All other SSRI:s are also metabolised by cytochrome P450 enzymes (6). Theoretically, a metabolic drug interaction is possible since venlafaxine, SSRI:s and colchicine are demethylated in the liver. Since the enzymes responsible for colchicine metabolism are not known it is impossible to predict whether a clinically relevant drug interaction may occur.

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