Adverse effects of zotepine and their relationship to serum concentrations of the drug and prolactin.

Adverse effects of zotepine, an antipsychotic drug, and their relationship to serum concentrations of the drug and prolactin were investigated in 28 schizophrenic in-patients. The daily dose was 100 mg during the first week and 200 mg during the next 3 weeks. Adverse effects were evaluated by the UKU Side Effect Rating Scale (21 items). The mean (+/- SD) total UKU score at the end of the study was 3.1 +/- 2.5, indicating mild adverse effects. The scores of psychic adverse effects at 2 weeks and total adverse effects at 3 and 4 weeks were significantly higher in nonresponders than in responders (p < 0.05). Furthermore, there was a significant inverse correlation between percent improvement in total Brief Psychiatric Rating Scale (BPRS) scores and total UKU scores at 4 weeks (p < 0.05). These results suggest a relationship between poor clinical response and increased adverse effects during zotepine treatment. Only the scores of akathisia at 2 weeks showed a significantly positive correlation with serum zotepine concentrations (p < 0.05). No correlation was found between prolactin response and neurological adverse effects.