Effects of two analgesic opiates (methadone and pentazocine) on the serum prolactin levels in breast cancer.

In 18 female patients affected by advanced breast cancer, the serum prolactin (PRL) levels have been determined under basal conditions and after the administration of analgesic opiates such as methadone and pentazocine. A significant increase of prolactin serum values was found after the use of both drugs. This finding is considered to be of clinical importance.