Resumen:
Objective: Neuropsychiatrists often resort to drugs with broad interindividual pharmacokinetic variability metabolized by highly polymorphic enzymes such as CYP2D6 and CYP2C19. Pharmacokinetics and pharmacogenetics offer considerable promise as techniques capable to allow individualized adjustments in treatments with psychoactive drugs. The purpose of this study was to review the existing evidence for the application of pharmacokinetics and pharmacodynamics to the dosing of drugs used in neuropsychiatry.
Method: A literature search was conducted in PubMed and Embase to find prospective studies published between January 2000 and April 2021 that used determination of psychotropic drug plasma levels or genotyping to improve response to treatment or minimize adverse events in adult patients with psychiatric conditions. MeSH terms and free search terms were used. Each article was reviewed by two independent reviewers to ensure that they met the inclusion criteria. A quantitative method was established to assess the quality of the articles selected.
Results: A total of 27 articles met the inclusion criteria of which 16 used pharmacokinetic and 11 pharmacogenetic techniques. Fifty percent of pharmacokinetic studies met the five predefined quality criteria. Eight of the 16 papers were on antidepressants; the remainder were on antipsychotics. Two of the latter did not find an association with efficacy or safety. None of the pharmacogenetic studies met the five quality criteria. Only one of the two studies on antipsychotics found fewer adverse events with genetics- guided dosing in patients on CYP2D6 substrate antipsychotics. Six of the nine studies on antidepressants found that pharmacogenetics-based dosing improved efficacy.
Conclusions: The evidence available on pharmacokinetics and pharmacodynamics-based personalization of treatment with psychoactive drugs is scarce. Many existing studies analyze associations between genotypes and response or toxicity but provide few data on the efficacy of treatment individualization. The results obtained suggest the existence of significant differences in pharmacokinetic parameters between responding and nonresponding patients, particularly in the treatment of depression. Given that the availability of pharmacogenetic information may be useful at the beginning of treatment, combining both techniques could help optimize pharmacotherapy. However, clinical trials are needed to establish their benefits with greater accuracy.
