Drug extrapyramidal side-effects or not: is there a dextromethorphan phenotype difference?

A recent hypothesis suggests the possible role of cytochrome P450 2D6 (CYP2 D6) polymorphism (involved in the metabolism of a large number of drugs), a s a potential risk factor for the development of extrapyramidal side-effect s of psychotropic drugs. The CYP2D6 metabolizer phenotype (dextromethorphan test) of 31 drug treated psychiatric adult patients suffering from extrapy ramidal side-effects (group 1) and of 31 matched patients without drug side effects (group 2) were compared. In the first group, 13 poor metabolizer p atients (41.9 per cent) were found, characterized by a dextromethorphan met abolic ratio >0.3, and only two patients in the second group (6.4 per cent) . These data provide some support for the notion that in subjects in whom C YP2D6 is probably saturated, the risk of drug extrapyramidal side-effects m ay be increased. In such patients the choice of psychotropic drugs 'without ' this risk must be prefered.