Escitalopram is an antidepressant extensively metabolized by the polymorphic CYP2C19 enzyme. Based on CYP2C19 genotype, patients can be classified either as:~Normal metabolizers (Normal CYP2C19 enzyme capacity)~Intermediate metabolizers (Decreased CYP2C19 enzyme capacity)~Poor metabolizers (Absent CYP2C19 enzyme capacity)~Ultra rapid metabolizers (Increased CYP2C19 enzyme capacity)~Adequate escitalopram exposure is needed to achieve optimal clinical response in the treatment of depression: too low drug plasma levels can lead to the lack of pharmacological effect, whereas too high drug plasma levels increases the incidence of adverse effects. There is evidence that patients with variant CYP2C19 genotypes have abnormal escitalopram exposure and could benefit from escitalopram dose personalization, but precise evidence-based protocol for personalized dosing of escitalopram has not been developed yet. This multicentric observational clinical trial is designed to collect crucial information for the development of such protocol that will be based on drug plasma level monitoring and/or CYP2C19 genotyping.~The course of the study will be as follows:~Initial Visit (V0):~Participant will be enrolled at this point if inclusion criteria are met. Escitalopram therapy will be initiated at the standard dose of 10 mg/day during next 2 weeks, or alternatively, started with 5 mg/day during first week and then increased to 10 mg/day during second week. General and socio-demographic information about the participant will be collected together with the baseline measurements: clinical questionnaires, anthropometric measurements, cardiology assessments, and the blood sample will be taken for biochemical analyses.~Mid-Visit (VK):~This visit takes place two weeks after the initial visit (V0) when escitalopram blood level is expected to reach the steady state. Blood sample will be taken from the participants at the end of the dose interval (before the morning dose) for the purpose of therapeutic drug monitoring. Plasma escitalopram levels will then be measured before the next visit and an independent clinician will allocate patients into one out of two cohorts based on whether or not escitalopram levels were optimal (25 - 50 ng/ml). If escitalopram levels were outside this interval, independent clinician will adjust the dose; escitalopram level lower than 5 ng/ml indicates noncompliance and results in dropout, level between 5 and 15 ng/ml results in dose increase to 20 mg/day, level between 15 and 25 ng/ml results in dose increase to 15 mg/day, level between 25 and 50 ng/ml results in treatment continuation with 10 mg/day, and level higher than 50 ng/ml results in dose decrease to 5 mg/day.~Visit 1 (V1):~Visit 1 takes place two weeks after VK and 4 weeks after the initiation of the escitalopram therapy. Without the knowledge of the attending clinician, independent clinician will adjust escitalopram doses accordingly. Attending clinician will then assess the participants using standardized questionnaires, participants will be anthropometrically and cardiologically examined, and blood samples will be taken for the purposes of therapeutic drug monitoring and biochemical analyses.~Visit 2 (V2):~Visit 2 is the final follow-up visit and it will be performed 4 weeks after the Visit 1 and 8 weeks after the escitalopram initiation. All participants will be assessed for psychometrical, anthropometrical and cardiological parameters, and blood samples will be taken again for the purposes of therapeutic drug monitoring and biochemical analysis.~If needed, additional participants, who are already on the stable escitalopram monotherapy, can be enrolled into study starting from VK. In this case, besides the blood sample for the therapeutic drug monitoring, all assessment usually done at initial visit (V0) will be performed during VK.
The aims of this study are to:~Determine the proportion of participants who are underdosed or overdosed under recommended dosing regimen of escitalopram for the depression treatment (10 mg/day)~Determine and quantify clinical benefits of personalized escitalopram dosing regimen based on the escitalopram blood level monitoring~Retrospectively estimate whether the information on CYP2C19 genotype is useful in the prediction of escitalopram blood level.