Cabergoline treatment rapidly improves gonadal function in hyperprolactinemic males: a comparison with bromocriptine

This study evaluated the effects of chronic treatment with cabergoline (CAB), a new, potent and long-lasting ergoline-derived dopamine agonist, on seminal fluid parameters and sexual and gonadal function in hyperprolactinemic males in comparison with the effect of bromocriptine (BRC) treatment. Seventeen males with macroprolactinoma were treated with CAB at a dose of 0.5-1.5 mg/week (n = 7), or BRC at a dose of 5-15 mg/day (n = 10) for 6 months. Baseline prolactin (PRL) was 925.7 +/- 522.6 microg/l in the CAB-treated group and 1059.4 +/- 297.6 microg/l in the BRC-treated group. All the patients suffered from libido impairment, ten from reduced sexual potency, and six had infertility. In five patients provocative bilateral galactorrhea was found. Seminal fluid analysis, functional seminal tests and penis rigidity and tumescence, measured by nocturnal penile tumescence (NPT) using Rigiscan equipment, were assessed before and after 1, 3 and 6 months of CAB or BRC treatment. Hormone profiles were assessed before and after 15, 30, 60, 90 and 180 days of both treatments. Before treatment, all patients had a low sperm count with oligoasthenospermia, reduced motility and rapid progression with an abnormal morphology and decreased viability, and a low number of erections. After 1 month, serum PRL levels were significantly reduced in both groups of patients (20.6 +/- 6.6 microg/l during CAB and 256.3 +/- 115.1 microg/l during BRC treatment) and were normalized after 6 months in all patients (CAB: 7.9 +/- 2.2 microg/l; BRC: 16.7 +/- 1.8 microg/l). After 6 months, a significant increase of number, total motility, rapid progression and normal morphology was recorded in patients treated with both CAB and BRC. An increase in the number of erections during the first 3 months of both treatments was noted by NPT. However, the improvements in seminal fluid parameters and sexual function were more evident and rapid in patients treated with CAB. The number of erections was normalized after 6 months of treatment in all patients submitted to CAB treatment, and in all patients but one treated by BRC. In addition, a significant increase of serum testosterone (from 3.7 +/- 0.3 to 5.3 +/- 0.2 microg/l) and dihydrotestosterone (from 0.4 +/- 0.1 to 1.1 +/- 0.1 nmol/l) was recorded. At the beginning of treatment, mild side-effects were recorded in two patients after CAB and mild-to-moderate side-effects in five patients after BRC administration. The treatment with CAB normalized PRL levels, improving gonadal and sexual function and fertility in males with prolactinoma, earlier than did BRC treatment, providing good tolerability and excellent patient compliance to medical treatment.