CABERGOLINE IN THE TREATMENT OF ACROMEGALY - A STUDY IN 64 PATIENTS

Cabergoline is a new, long acting, dopamine agonist that is more effec tive and better tolerated than bromocriptine in patients with hyperpro lactinemia. Because dopamine agonists still have a place in the medica l management of acromegaly, cabergoline might be a useful treatment. W e, therefore, evaluated the effect of long term administration of cabe rgoline in a large group of unselected acromegalic patients. Sixty-fou r patients were included in a multicenter, prospective, open labeled s tudy. A subgroup of 16 patients had GH-/PRL-cosecreting pituitary aden omas. Cabergoline was started at a dose of 1.0 mg/week and was gradual ly increased until normalization of plasma insulinlike growth factor I (IGF-I) levels, occurrence of unacceptable side-effects, or a maximal weekly dose of 3.5 mg (7.0 mg in 1 case) was reached. Treatment with cabergoline suppressed plasma IGF-I below 300 mu g/L in 39% of cases a nd between 300-450 mu g/L in another 28%. With pretreatment plasma IGF -I concentrations less than 750 mu g/L, a suppression of IGF-I below 3 00 mu g/L was obtained in 53% of cases, and a suppression between 300- 450 mu g/L was obtained in another 32%. By contrast, with pretreatment plasma IGF-I concentrations above 750 mu g/L, only 17% of cases showe d a suppression of IGF-I below 300 mu g/L, and there was IGF-I suppres sion between 300-450 mu g/L in another 21%. In GH-/PRL-cosecreting ade nomas, 50% of cases suppressed plasma IGF-I levels below 300 mu g/L, a nd another 31% did so between 300-450 mu g/L, in contrast to only 35% and 27%, respectively, in GH-secreting adenomas. Similar results were obtained concerning the secretion of GH. Tumor shrinkage was demonstra ted in 13 of 21 patients, with a mass reduction by more than half in 5 GH-/PRL-cosecreting adenomas. Except for slight gastrointestinal disc omfort and orthostatic hypotension in a few patients at the beginning of therapy, cabergoline treatment was well tolerated. Only 2 patients stopped medication because of nausea. The weekly dose of cabergoline r anged between 1.0-1.75 mg. A further increase in the dose was only eff ective in 1 GH-/PRL-cosecreting adenoma. The results of this study sug gest that cabergoline is an effective, well tolerated therapy that sho uld be considered in the management of acromegaly, especially if the p ituitary adenoma cosecretes GH and PRL or if pretreatment plasma IGF-I levels are below 750 mu g/L.