[Short-term effect of delayed-action injectable bromocriptine in macroprolactinoma. French multicenter study]

In this prospective multicenter trial, 61 patients presenting with a macroprolactinoma were studied over a 1 month-period following a single 50 mg intragluteal injection of the long-acting repeatable (L.A.R.) form of bromocriptine. The effects of the drug were evaluated mainly by repetitive plasma prolactin measurements on days 1, 3, 7, 14 and 28 after injection, and by repeated visual-field and computed tomography scanning examinations. Normalization of PRL levels was obtained in 23% of patients during the first month following injection. In 6 patients (9.8%), PRL values remained within normal range on day 28 after injection. In these latter patients, PRL levels were significantly lower than in the patients whose PRL values were not normal on day 28 (312 +/- 111 vs 2454 +/- 484 ng/ml [m +/- SEM]). The mean lowest PRL levels were achieved on day 3. The mean percent maximal decrease in PRL levels ranged between 70 and 72% from days 3 to 14 but constantly remained below 50% in 6 patients. An improvement in visual field was observed by day 7 in 45% of patients presenting initially with visual field defects. In particular, in half of the patients with bilateral quadranopsia or hemianopsia, such visual impairments had disappeared after 1 month of treatment. Computed tomography scanning examinations showed in 11% of the patients a more than 20% reduction in tumor mass by day 7 following injection. On day 28, the percent reduction in tumor size was 20-40% in 28% and above 40% in 10% of the patients. Most adverse effects (digestive symptoms, dizziness, postural hypotension) were observed during the first 24 hours of treatment. Local and systemic tolerability was in general good. In macroprolactinoma patients, a single 50 mg injection of bromocriptine LAR was thus able to achieve in the short-term a clear cut reduction in tumor size in 2/5 patients and normalization of PRL levels in 1/10 of patients. A study of the effects of monthly administration of bromocriptine LAR is currently under progress to assess the long-term efficacy of this drug.