Alternative Treatment Strategies in Women Poorly Tolerating Moderate Doses of Bromocriptine.

Metformin as well as dopaminergic agents exert a beneficial effect on glucose and lipid metabolism, often impaired in patients with hyperprolactinemia. The aim of this study was to compare metabolic- and prolactin-lowering effects of low-dose bromocriptine/metformin combination therapy and cabergoline in patients with elevated prolactin levels. The study included 27 women with hyperprolactinemia and impaired glucose tolerance who were treated with moderate doses of bromocriptine but experienced adverse effects of this treatment. In 12 of these patients bromocriptine was replaced with cabergoline (group A), while the remaining ones continued treatment with bromocriptine, the dose of which was halved, and administered together with metformin (group B). Plasma lipids, glucose homeostasis markers, as well as serum levels of prolactin, thyrotropin and insulin-like growth factor-1 (IGF-1) were assessed before and after 4 months of metformin treatment. Both groups did not differ in baseline levels of plasma glucose and lipids, in insulin sensitivity, as well as in circulating levels of all measured hormones. All patients from group A and 12 patients from group B completed the study. Cabergoline reduced prolactin levels, while no effect on plasma prolactin was found in group B. Neither cabergoline nor bromocriptine plus metformin affected circulating levels of thyrotropin and IGF-1. Both treatment options, particularly low-dose bromocriptine plus metformin, improved glucose and lipid homeostasis. Low-dose bromocriptine combined with metformin may be an interesting alternative to cabergoline in patients with mild hyperprolactinemia and early glucose metabolism abnormalities, in whom moderate doses of bromocriptine are poorly tolerated.