EFFECTIVENESS OF A LONG-ACTING INJECTABLE FORM OF BROMOCRIPTINE IN PATIENTS WITH PROLACTIN AND GROWTH-HORMONE SECRETING MACROADENOMAS

OBJECTIVE With the development of new long-acting depot preparations o f bromocriptine (bromocriptine LAR), we investigated the effectiveness of intramuscular injections of long-acting bromocriptine in patients with prolactin and GH secreting macroadenomas. STUDY DESIGN AND PATIEN TS Fourteen patients with PRL secreting (8 patients) and GH secreting (6 patients) macroadenomas were treated with monthly intramuscular inj ections of a long-acting and repeatable form of bromocriptine for 3-6 months. A 50-mg monthly dose was administered in the majority of patie nts with PRL secreting macroadenomas. A 100-mg monthly dose was admini stered in all patients with GH secreting macroadenomas. MEASUREMENTS P lasma PRL and/or GH levels were measured 6 and 12 hours after the firs t injection and then on days 1, 2, 14 and 28 after each injection, up to a maximum period of 6 months. Patients were hospitalized for 48 hou rs after each injection and were specifically questioned with respect to side-effects. Pituitary imaging with MRI or CT scans was performed in all patients before commencing treatment and was subsequently repea ted in 5/8 patients with macroprolactinomas and 5/6 patients with GH s ecreting macroadenomas after the completion of a 6-month course al tre atment. RESULTS I all patients with macroprolactinomas, serum PRL leve ls decreased significantly after their first 50-mg injection with nadi r levels obtained by 24-48-hours post injection (12 815 +/- 8704 vs 14 80 +/- 1859 mU/l; mean +/- SD, P < 0.01). At their latest follow-up, o n a 50-mg monthly dose, 4 patients developed normoprolactinaemia (PRL levels <360 mU/l) while two patients demonstrated a significant reduct ion in serum PRL levels (70 and 87% of pretreatment values). In two pa tients, although a substantial decrement of serum PRL levels was achie ved 12-24 hours post injection, serum PRL levels increased to pretreat ment values by day 14 post injection. Both patients received a higher (100 mg) monthly dose which was partially effective in one patient. In two patients with GH secreting macroadenomas, a sustained decrease of elevated GH levels was observed; in two patients, while a substantial reduction of the elevated serum GH levels was achieved 12-24 hours af ter the first and subsequent injections, serum GH levels increased to pretreatment values by day 14 post injection; in two patients there wa s no effect on the elevated serum GH levels. Significant tumour shrink age (24-50%) was observed in 5/5 patients with PRL secreting macroaden omas assessed at completion of a 6-month course of treatment. Signific ant tumour shrinkage was also documented in 2/5 acromegalics tested (2 9 and 46% respectively). CONCLUSION It is concluded that bromocriptine LAR is an effective treatment in the majority of patients with macrop rolactinomas; it is also partially effective in some patients with GH secreting macroadenomas.