Switching rx may reduce hyperprolactinemia.
Minimizing treatment-associated sexual morbidity improves patient well-being and could strengthen the therapeutic alliance, Dr. Houston of Lilly Research Laboratories, Indianapolis, said at a poster session. Eli Lilly & Co. sponsored the research.
The study included 54 subjects chosen from a group of 402 patients with schizophrenia who had been taking risperidone (Risperdal) or one of the conventional antipsychotic agents haloperidol (Haldol) and fluphenazine for at least 3 months. Hyperprolactinemia, defined as serum levels greater than 18.77 ng/mL in men or greater than 24.2 ng/mL in women, was observed in 42% of the men and 59% of the women in the larger group. Regression analysis showed that hyperprolactinemia was significantly associated with a greater risk of erectile dysfunction among men taking risperidone but not in those taking the conventional agents, and a slight but statistically significant risk of decreased interest in sex among women in both groups.
All 54 patients who participated in the study had hyperprolactinemia and sexual dysfunction, defined as a baseline score of three or more on the Clinical Global Impressions-Sexual Function Scale (CGI-SF), on which higher scores indicate greater sexual dysfunction, up to a maximum score of seven. The patients' baseline scores on the Changes in Sexual Functioning Questionnaire (CSFQ), which measures the effects of illness or medication on sexual function and desire, were also recorded.
At baseline, 27 patients were randomized to receive olanzapine at a beginning dosage of 5 mg/day; dosage was increased when necessary in weekly increments of 5 mg, up to a maximum dosage of 20 mg/day. Their current medication was tapered simultaneously so that all patients in this group were on monotherapy by week 2. The remaining 27 patients remained on their current therapy for the duration of the 4-month study. There were 13 men and 14 women in each group. Their prolactin levels were measured monthly and their sexual functioning assessed at the end of the study.
Among the men, mean baseline serum prolactin levels were 33.66 ng/mL and 33.45 ng/mL in the olanzapine and control groups, respectively. Among women, the levels were 66.32 ng/mL in the olanzapine group and 81.95 ng/mL in the control group. None of the differences were statistically significant. By the final evaluation, more than 90% of patients in the olanzapine group had achieved normal prolactin levels, compared with none of the patients taking risperidone or conventional antipsychotic drugs.
Patients switched to olanzapine reported a mean decrease in CGI-SF scores of 0.65 points over the course of the study, significantly more than the mean decrease of about 0.15 points in the control group.
On the CSFQ, male patients were asked if they were able to experience an erection or ejaculation whenever they wished. Responses ranged from 1 (never) to 5 (always). At baseline, the mean scores were 3.36 among men in the olanzapine group and 2.88 in those who did not switch medication. By the study's end, scores had improved by a mean of 0.6 points among the men in the olanzapine group, compared with a mean decline of 0.5 points in the control group. Female patients were asked on the CSFQ how often they experienced painful intercourse. As with the men, responses ranged from 1 (never) to 5 (always), but this time lower scores indicated better functioning.
Despite the open-label protocol, the changes in the subjects' prolactin levels were objective evidence that the risk of hyperprolactinemia is lower with olanzapine than with risperidone or the conventional antipsychotic agents, Dr. Houston told this newspaper.
BY NORRA MACREADY
Los Angeles Bureau