Background: Schizophrenia represents a major burden on mental health services globally, and there are nearby 15 million cases in India. The treatment of schizophrenia promises improvement only with long-term medication, but noncompliance, adverse reactions and interactions are a major hurdle in the pathway. Methods: A six-month prospective study was conducted at the MDM Hospital, Jodhpur. Schizophrenic patients (n= 205) aged 18-70 years and prescribed with antipsychotics were evaluated for drug interactions (DI) and adverse drug reactions (ADR). Extrapyramidal symptoms (EPS) were evaluated at baseline and endpoint; weight gain and lipid profile were evaluated at variable time points.

Results: In the present study, 463 interactions occurred; 70 were of major severity. Antipsychotics were involved in 42% of the total interactions, amongst which haloperidol (21.5%), and olanzapine (10.3%) were involved in most, while aripiprazole (3.48%) was involved in least interactions. A total of 194 ADRs including 19 severe (5, arrhythmia, 4, tremor, and 10, EPS) were reported. Other frequently reported ADRs were insomnia, anxiety, dry mouth and EPS. Weight gain in the aripiprazole vs. olanzapine group was 0.23 kg vs. 2.74 kg (p< 0.001). Patients on olanzapine vs. aripiprazole experienced elevated total cholesterol (6.7 mg/dl vs.-11.2 mg/dl), low density lipoprotein (4.3 mg/dl vs.-13.2 mg/dl), and triglyceride levels (12.7 mg/dl vs.-22.13 mg/dl). Conclusion: Reasons of non-compliance and inadequate clinical improvement in schizophrenia are long-term medication, ADRs and drug interactions. ADRs and interactions were least in aripiprazole prescriptions. Further long-term studies are required (German J Psychiatry 2011; 14: 26-34).