Effects of antipsychotic polypharmacy on side‐effects and concurrent use of medications in schizophrenic outpatients

AIMS: Medical therapy is the cornerstone of schizophrenia, but >50% of patients do not adhere to medication regimens. In previous reports, the reasons for non-adherence were assessed only by medical staff. We think that patients have specific reasons for non-adherence. We researched whether there was an association between patients' subjective opinions and the number of antipsychotics used. METHODS: A self-rating questionnaire survey was conducted on 252 outpatients with schizophrenia at five psychiatric hospitals in Japan. Based on patients' subjective opinions, we retrospectively analyzed the patients' medications: the number of antipsychotics, concurrently used agents, and dosages of antipsychotics. RESULTS: There was no significant difference regarding attitudes toward medication between monotherapy and polypharmacy. The most common reason for not taking medications was 'I sometimes forget' followed by 'side-effects'. Of the latter, weight gain was the most common, and dry mouth (P < 0.05) and sexual dysfunction (P < 0.01) were significantly higher in polypharmacy. The dosages of antipsychotics (P < 0.01), concurrent use of anti-Parkinsonian agents (P < 0.01), and the number of side-effects (P < 0.01) were also higher in polypharmacy. CONCLUSIONS: Patients had good attitudes toward medication but a higher prevalence of side-effects was seen in polypharmacy of antipsychotics. Hence, monotherapy may be a more appropriate prescription with respect to side-effects. By using monotherapy, patients may reduce feelings of discomfort due to side-effects.