Trends in the Outpatient Utilization of Antipsychotic Drugs in the City of Zagreb in the Ten-Year Period as a Tool to Assess Drug Prescribing Rationality.

BACKGROUND The aim was to determine distribution and trends in the outpatient utilization of antipsychotics to evaluate the rationality of antipsychotic drug prescribing during the ten year period. SUBJECTS AND METHODS The epidemiological method of descriptive and analytical observation was used. Data on drug utilization from Zagreb Municipal Pharmacy were used to calculate the number of defined daily doses (DDD) and DDD per 1000 inhabitants per day (DDD/TID) using the World Health Organization Anatomical-Therapeutic-Chemical methodology. The ratio of typical versus atypical antipsychotics served as an indicator on assessing the rationality of the utilization. Data on the use of anticholinergics in the treatment of neuroleptic side effects were also included. RESULTS Outpatient utilization of antipsychotics showed a declining pattern from 14.17 in 2001 to 8.42 DDD/TID in 2010. The utilization of atypical antipsychotics increased by 60% (from 3.68 to 5.89 DDD/TID), while the utilization of typical antipsychotics decreased by 76% (from 10.49 to 2.53 DDD/TID). The drugs showing the largest increase were olanzapine (from 1.21 to 2.78 DDD/TID) and quetiapine (from 0 to 0.68 DDD/TID). The typical/atypical antipsychotic ratio changed from 1:0.4 in 2001 to 1:2.3 in 2010. A 2.3-fold decrease was recorded in the utilization of anticholinergics (from 2.05 to 0.91 DDD/TID). CONCLUSIONS Total consumption of neuroleptics significantly decreased. A decrease was also recorded in the utilization of anticholinergics. Study results pointed to two favorable features, i.e. low use of typical antipsychotics and the ratio of typical and atypical antipsychotics. Implementation of the new clinical guidelines for nervous system disorders and updating of the list of reimbursable drugs with the addition of new ones contributed to the observed improvement in the prescribing patterns during the study period. Using the WHO ATC/DDD methodology and rationality indicators in the assessment of trends in the outpatient utilization of psychopharmaceuticals over a ten-year period proved efficient in the evaluation of prescribing rationality.