Bromocriptine compared to long-acting estrogens in lactation prevention: clinical efficacy, prolactin secretion and coagulation parameters.

Sixty-eight mothers who did not want to breast-feed their babies were submitted to one of the following regimes: an intramuscular injection of estrogen (25 mg) within 1 h after delivery (n = 24) or the administration of bromocriptine for 15 or 23 days (n = 21 and 23, respectively). A careful clinical evaluation was performed every day by the same examiner during the first 7 days postpartum; blood samples were collected on days 0, 3 and 5 for human prolactin (hPRL) and estradiol, also in some cases on day 17; assays were measured by radioimmunoassay. An evaluation of the coagulation parameters was performed on day 5 in 9 estrogen-treated patients and in 25 bromocriptine-treated patients. Only 5 (11%) out of the 44 patients treated with bromocriptine experienced at least one undesirable effect of breast engorgement, in contrast to 16 (67%) out of the 24 estrogen-treated patients; this difference was statistically highly significant (P less than 0.001). Dizziness was a significant side-effect of bromocriptine treatment, occurring in 20% of the cases. In the patients in whom the administration of bromocriptine was withdrawn after 15 days, a significant mean rebound elevation of hPRL levels above the normal range occurred on the 17th day. The latter observation gives some support to earlier proposals to continue bromocriptine for up to a total 3 wk in order to avoid rebound lactation. There was no significant alteration of fibrinogen, Howell time, activated partial thromblastin time (APTT), prothrombin time (PT), thrombin time and coagulation time; mean plasminogen levels were comparable in both treated groups, while mean antithrombin III levels were increased in the bromocriptine-treated group. The significance of the latter finding requires further evaluation.