Cabergoline is a new long-acting
dopamine agonist that is very effective and well tolerated in patients with pathological
hyperprolactinemia. The aim of this study was to examine, in a very large number of hyperprolactinemic patients, the ability to normalize PRL levels with
cabergoline, to determine the effective dose and tolerance, and to assess the effect on clinical symptoms,
tumor shrinkage, and visual field abnormalities. We also evaluated the effects of
cabergoline in a large subgroup of patients with
bromocriptine intolerance or -resistance. We retrospectively reviewed the files of 455 patients (102 males and 353 females) with pathological
hyperprolactinemia treated with
cabergoline in 9 Belgian centers. Among these patients, 41% had a microadenoma; 42%, a macroadenoma; 16%, idiopathic
hyperprolactinemia; and 1%, an empty sella. The median pretreatment serum PRL level was 124 microg/L (range, 16-26,250 microg/L). A subgroup of 292 patients had previously been treated with
bromocriptine, of which 140 showed
bromocriptine intolerance and 58 showed
bromocriptine resistance. Treatment with
cabergoline normalized serum PRL levels in 86% of all patients: in 92% of 244 patients with idiopathic
hyperprolactinemia or a
microprolactinoma and in 77% of 181 macroadenomas. Pretreatment visual field abnormalities normalized in 70% of patients, and
tumor shrinkage was seen in 67% of cases. Side effects were noted in 13% of patients, but only 3.9% discontinued
therapy because of side effects. The median dose of
cabergoline at the start of
therapy was 1.0 mg/week but could be reduced to 0.5 mg/week once control was achieved. Patients with a
macroprolactinoma needed a higher median
cabergoline dose, compared with those with idiopathic
hyperprolactinemia or a
microprolactinoma: 1.0 mg/week vs. 0.5 mg/week, although a large overlap existed between these groups. Twenty-seven women treated with
cabergoline became pregnant, and 25 delivered a healthy child. One patient had an intended abortion and another a
miscarriage. In the patients with
bromocriptine intolerance, normalization of PRL was reached in 84% of cases, whereas in the
bromocriptine-resistant patients, PRL could be normalized in 70%. We confirmed, in a large-scale retrospective study, the high efficacy and tolerability of
cabergoline in the treatment of pathological
hyperprolactinemia, leaving few patients with unacceptable side effects or inadequate clinical response. Patients with idiopathic
hyperprolactinemia or a
microprolactinoma, on average, needed only half the dose of
cabergoline as those with
macroprolactinomas and have a higher chance of obtaining PRL normalization.
Cabergoline also normalized PRL in the majority of patients with known
bromocriptine intolerance or -resistance. Once PRL secretion was adequately controlled, the dose of
cabergoline could often be significantly decreased, which further reduced costs of
therapy.