CYP2C19 genotype, physician prescribing pattern, and risk for long QT on serotonin selective reuptake inhibitors

[Pharmacogenomic and pharmacometabolomic biomarkers of the efficacy and safety of antidepressants: focus on selective serotonin reuptake inhibitors]

The efficacy and safety of psychopharmacotherapy with antidepressants is of great medical importance. The search for clinical and biological predictors for choosing the optimal psychopharmacotherapy with antidepressants is actively underway all over the world. Research is mainly devoted to searching for associations of polymorphic gene variants with the efficacy and safety of therapy. However, information about a patient's genetic polymorphism is often insufficient to predict the efficacy and safety of a drug. Modern research on the personalization of pharmacotherapy should include, in addition to genetic, phenotypic biomarkers. This is important because genotyping, for example, cannot accurately predict the actual metabolic activity of an isoenzyme. To personalize therapy, a combination of methods is required to obtain the most complete profile of the efficacy and safety of the drug. Successful treatment of depression remains a challenge, and inter-individual differences in response to antidepressants are common. About half of patients with depressive disorders do not respond to the first attempt at antidepressant therapy. Serious side-effects of antidepressant pharmacotherapy and discontinuation of treatment due to their intolerance are associated with ineffective therapy. This review presents the results of the latest studies of «omics» biomarkers of the efficacy and safety of antidepressants.

Pharmacogenetic Testing and Therapeutic Drug Monitoring Of Sertraline at a Residential Treatment Center for Children and Adolescents: A Pilot Study

Background: Sertraline is commonly prescribed to children for the treatment of anxiety and major depressive disorder and is metabolized in part by CYP2C19. While dosing recommendations based on CYP2C19 genotype exist, there is sparse data in children on the relationship between sertraline concentrations and CYP2C19 genotype. Additionally, although rarely utilized in the United States, therapeutic drug monitoring can also help to guide dosing. The primary objective of this pilot study was to compare sertraline concentrations with CYP2C19 genotype. Secondary objectives included exploring the feasibility of using pharmacogenetic testing and therapeutic drug monitoring in a residential treatment center for children and adolescents. Methods: This study was a prospective, open-label study of children prescribed sertraline being treated at a residential treatment center for children and adolescents. Individuals were included if they were < 18 years of age, taking sertraline for at least 2 weeks allowing them to reach steady-state concentrations, being treated through the residential treatment program, and able to understand and speak English. Results: A total of 20 participants (80% female) completed all study procedures, including pharmacogenetic testing and therapeutic drug monitoring, with an average age of 15.4 years (range: 9-17 years). Forty percent (n=8) of participants had a diagnosis of Generalized Anxiety Disorder, while 30% (n=6) had a diagnosis of Major Depressive Disorder. Overall, average sertraline and desmethylsertraline concentrations were 21.1 ng/ml (range: 1-78 ng/ml) and 52.4 ng/ml (range: 1-258 n/ml). Based on CYP2C19 genotypes, 60% (n=12) were normal metabolizers, 10% (n=2) were intermediate metabolizers, and 30% (n=6) were rapid metabolizers. Daily sertraline dose (mg/day) accounted for a significant amount of the observed variability in sertraline (p<0.0001; r2=0.62) and desmethylsertraline concentrations (p<0.001; r2=0.45). When comparing weight-based dosing by sertraline and desmethylsertraline concentrations, sertraline daily dose by weight (mg/kg/day) also accounted for a significant amount of the observed variability in sertraline (p<0.0001; r2=0.60) and desmethylsertraline (p<0.0001; r2=0.59) concentrations. Average daily and weight-based doses for CYP2C19 intermediate, normal, and rapid metabolizers were 75 mg/day, 87.5 mg/day, and 79.2 mg/day and 1.5 mg/kg/day, 1.3 mg/kg/day, and 1.1 mg/kg/day, though these were not significantly different. Conclusion: This small, pilot study showed sertraline dose to be significantly associated with sertraline and desmethylsertraline concentrations. No differences were noted between CYP2C19 metabolizer groups, likely due to the limited sample size. These results also suggest that ordering pharmacogenetic testing and therapeutic drug monitoring in the setting of a child and adolescent residential treatment center is feasible.

CYP2C19 slow metabolizer phenotype is associated with lower antidepressant efficacy and tolerability

The inter-individual variability in CYP2C19-mediated metabolism may affect the antidepressant treatment. The aim of this study is to evaluate differences in antidepressant efficacy and tolerability between different CYP2C19 metabolizer categories in inpatients suffering from major depressive disorder. The cohort was divided into experimental groups based on CYP2C19 genotype and it contained 24 slow (SMs), 41 normal (NMs), and 37 fast metabolizers (FMs). Efficacy and tolerability were assessed at baseline, and after two and four weeks as a follow-up. The primary efficacy measurement was the change from baseline in Hamilton's Depression Rating Scale (HAMD), while the primary tolerability measurement was the Toronto Side-Effects Scale (TSES) intensity scores at the last visit. The reduction in HAMD score was 36% less pronounced and response rate was exceedingly less prevalent (75% lower) in SMs, compared with NMs. The TSES intensity score was increased in SMs, compared with NMs, by 43% for central nervous system and by 22% for gastrointestinal adverse drug reactions. No significant differences in measured parameters were observed between NMs and FMs. Compared with NM and RM, lower antidepressant efficacy and tolerability was observed in SMs; this association is likely connected with the lower SM capacity to metabolize antidepressant drugs.

Potential Use of Pharmacogenetics to Reduce Drug-Induced Syndrome of Inappropriate Antidiuretic Hormone (SIADH)

Syndrome of inappropriate antidiuretic hormone (SIADH) is a common cause of hyponatremia, and many cases represent adverse reactions to drugs that alter ion channel conductance within the peptidergic nerve terminals of the posterior pituitary. The frequency of drug-induced SIADH increases with age; as many as 20% of patients residing in nursing homes have serum sodium levels below 135 mEq/L. Mild hyponatremia is associated with cognitive changes, gait instability, and falls. Severe hyponatremia is associated with cerebral edema, seizures, permanent disability, and/or death. Although pharmacogenetic tests are now being deployed for some drugs capable of causing SIADH (e.g., antidepressants, antipsychotics, and opioid analgesics), the implementation of these tests has been based upon the prior known association of these drugs with other serious adverse drug reactions (e.g., electrocardiographic abnormalities). Work is needed in large observational cohorts to quantify the strength of association between pharmacogene variants and drug-induced SIADH so that decision support can be developed to identify patients at high risk.

CYP2C19 genotype-guided antiplatelet therapy: promises and pitfalls

Pharmacogenetic variants can alter the mechanism of action (pharmacodynamic gene variants) or kinetic processes such as absorption, distribution, metabolism and elimination (pharmacokinetic gene variants). Many initial successes in precision medicine occurred in the context of genes encoding the cytochromes P450 (CYP enzymes). CYP2C19 activates the antiplatelet drug clopidogrel, and polymorphisms in the CYP2C19 gene are known to alter the outcome for patients taking clopidogrel in the context of cardiovascular disease. CYP2C19 loss-of-function alleles are specifically associated with increased risk for coronary stent thrombosis and major adverse cardiovascular events in patients taking clopidogrel following percutaneous coronary intervention. We explore successes and challenges encountered as the clinical and scientific communities advance CYP2C19 genotyping in the context of routine patient care.