Challenging pharmacotherapy management of a psychotic disorder due to a delicate pharmacogenetic profile and drug-drug interactions: a case report and literature review.

This report presents challenging psychopharmacotherapy management of a psychotic disorder in a patient with a delicate pharmacogenetic profile and drug-drug interactions. A 31-year old woman diagnosed with schizophrenia in 2017 was referred by her psychiatrist to a clinical pharmacologist for interpretation of a pharmacogenetic test and advice regarding optimal psychopharmacotherapy. In spite of adherence to aripiprazole, olanzapine, risperidone, and levomepromazine, and rational anxiolytic therapy, she still experienced anxiety, anhedonia, loss of appetite, sleeping problems, and auditory hallucinations with commands to harm herself. Due to a lack of alternative therapeutic steps, low aripiprazole serum concentrations, and a lack of explanation for pharmacotherapy unresponsiveness, pharmacogenetic testing was performed. The patient was defined as CYP2D6 *1/*1, CYP1A2 *1F/*1F, CYP3A4 *1/*1B, CYP3A5 *1/*3, and having increased activity of the enzymes UGT1A4 and UGT2B7, intermediate activity of ABCB1 transporter, and low activity of COMT. Carbamazepine was discontinued, aripiprazole was increased to a maximum of 30 mg/day orally with long-acting injection (400 mg monthly), and olanzapine was increased to a daily dose of 35 mg orally. These changes led to an optimal therapeutic drug concentration and improved clinical status. At the last follow-up, the patient was without severe auditory hallucinations, became more engaged in daily life, had more interaction with others, had found a job, and even had started an emotional relationship. In psychiatry, pharmacogenetic testing is an important tool for guiding pharmacological therapy, particularly in patients with an unsatisfactory clinical response and a lack of alternative therapeutic steps for pharmacotherapy unresponsiveness.