Pharmacoepidemiological study of antipsychotics in the psychiatry unit of a tertiary care hospital: A retrospective descriptive analysis

Abstract

Aims: Pharmacoepidemiology is an interface discipline that studies the interactions between drugs and populations. Pharmacoepidemiological studies reveal the differences that exist between the conditions of premarketing trials (done on a limited sample population) and those of actual practice. Antipsychotic prescribing patterns have changed globally over the last few years. Hence, we wanted to observe the prescribing pattern of antipsychotics in our hospital and assess the rationality of the prescriptions and the prevalence of antipsychotic usage in the community. Materials and Methods: This was a retrospective observational analysis of case records of patients receiving antipsychotic prescriptions in the psychiatry outpatient clinic of a tertiary care hospital during the period 1 st January 2006 to 31 st December 2006. We studied the following parameters: Antipsychotic drugs prescribed, completeness and rationality of prescriptions, WHO prescribing indicators, defined daily dose (DDD)/1000/day (DID), prescribed daily dose (PDD), and the PDD to DDD ratio. Results: Antipsychotics were prescribed in 32.88% patients (olanzapine: 65.66%, risperidone: 19.19%, aripiprazole: 7.07%, others: 8.08%). The average number of drugs/prescription: 2.19, prescribing by generic names: 63.64%, prescribing from WHO essential medicines list (EML) and injections: 3.03%. There were no prescriptions for fixed-dose combinations (FDC). DID of antipsychotics: 0.0008 mg. PDD to DDD ratios Conclusion: The second-generation antipsychotics olanzapine, risperidone, and aripiprazole were the most commonly prescribed antipsychotics. Prescriptions were complete and without polypharmacy. Favorable and unfavorable outcomes were seen for two and three WHO prescribing indicators, respectively. Antipsychotic consumption in the community was low. Adequate dosing was seen for all antipsychotics, except quetiapine and haloperidol (where there was underdosing). Choosing drugs from the EML-based hospital formulary will decrease cost of therapy and promote rational use of medicines.