This work aimed to describe and characterize the GnG-PK/PD-AD study and the population of subjects diagnosed with depression and treated with fluoxetine, paroxetine, and venlafaxine recruited in the scope of this project, particularly in terms of antidepressant pharmacokinetics and clinical outcomes and relevant genetic and nongenetic individual factors. 182 subjects diagnosed with depression and treated with these drugs were clinically and therapeutically characterized and submitted to the quantification of drug/metabolite plasma concentrations and genotyping of ABCB1, CYP2C9, CYP2C19, and CYP2D6 genes. Clinical outcomes, including remission and antidepressant adverse effects, were assessed by means of the Hamilton Depression Rating Scale and Antidepressant Side-Effect Checklist, respectively. Most subjects were women (81.9%), suffered from chronic depression (73.6%) and displayed a high prevalence of comorbidities (76.9%), polytherapy (88.5%), and genetic polymorphisms/non-wild-type genotype-predicted phenotypes at the level of CYP2C9, CYP2C19, CYP2D6, and ABCB1 genes (39-78.6%). Noteworthy, most of them were under risk of presenting P-gp, CYP2C9, CYP2C19, and CYP2D6 inhibited due to drug-induced phenoconversion (64.3-98.4%) and 80.8% were at risk of occurrence of at least one antidepressant-drug interaction. Around 40% presented drug plasma concentrations outside of the recommended therapeutic range, 66.5% did not achieve remission of the depressive symptoms and 67.6% presented at least one relevant antidepressant adverse effect. Pharmacokinetics and clinical outcomes with fluoxetine, paroxetine, and venlafaxine were found to be suboptimal and highly variable between subjects. Several genetic and nongenetic factors were identified as potential sources of interindividual variability in the antidepressant outcomes, which deserve to be further investigated. (PsycInfo Database Record (c) 2020 APA, all rights reserved).