Optimisation of psychopharmacotherapy: Clinical relevance of pharmacogenetic tests and therapeutic drug monitoring

Abstract

More than 100 psychoactive drugs are available for the treatment of psychiatric disorders. However, remission rates are far from being optimal, as a significant number of patients poorly respond or are intolerant to many drugs. The fate of drugs in the organism depends on environmental (diet, smoking habits, comorbidities, comedications) and genetic factors. Therapeutic plasma level monitoring (TDM) of psychotropic drugs represents a useful tool for optimising pharmacotherapy. It is recommended in patients mentioned above, but also in situations of poor compliance, longterm treatment, in elderly and very young patients, and in somatically ill and comedicated patients. The introduction of phenotyping and genotyping procedures allows taking account of the pharmacogenetic status (e.g. cytochrome P–450, P-glycoprotein) of the patients not only for adjustment of their medication, but also for interpreting pharmacokinetic interactions with clinical consequences. In this respect, TDM and pharmacogenetic tests (phenotyping, genotyping) have now also to be considered as a tool in pharmacovigilance. Recently, the AGNP-TDM expert group published consensus guidelines for TDM of psychotropic drugs (Baumann et al., Pharmacopsychiatry 37: 243–265, 2004). In addition, recommendations on the optimal use of TDM in combination with pharmacogenetic tests in psychiatry were summarized.