Effect of bromocriptine on sperm function in vitro and in vivo

Vaginal bromocriptine is an effective method for the treatment of hyperprolactinemia, but it is unknown whether bromocriptine applied vaginally can interfere with sperm function. Thus, we sought to determine the effects in vitro and in vivo on sperm directly exposed to bromocriptine. Ten semen specimens from normal donors were diluted with Ham's F-10 medium and incubated with 0, 0.01, 0.1, and 1.0 mmol/L bromocriptine solution or diluent without bromocriptine. Computerized semen analysis revealed a 31% decrease in sperm motility, a 24% decrease in sperm average path velocity, and a 33% decrease in sperm average straight line velocity only using 1.0 mmol/L of bromocriptine (P less than .05). In addition, eight women with hyperprolactinemia and infertility who were receiving vaginal bromocriptine consented to a postcoital test. Five became pregnant and delivered normal infants. Four of the five women who had a postcoital test had six, eight, ten, and ten motile sperm per high-power field and one had one to two motile sperm per high-power field. Because sperm function was preserved enough to result in fertilization and term pregnancy, the clinical importance of the in vitro findings is probably minimal and it can be concluded that vaginal bromocriptine can be used in women with infertility due to hyperprolactinemia.