Bromocriptine is a dopamine agonist widely used in the treatment of hyperprolactinaemia. This disorder is characterised by amenorrhoea and galactorrhoea in women and impotence in males. Infertility is a common presentation of hyperprolactinaemia. Therapy with bromocriptine is generally highly effective in suppressing the elevated prolactin levels and this is associated with a return to normal menstruation in females (secondary to restoration of ovulation) and return to normal sexual function in men. Bromocriptine has also been used to restore normal sexual function to uraemic men undergoing haemodialysis, who are frequently affected by reduced libido and potency disorders.
In Parkinson’s disease, however, the use of bromocriptine has been reported to induce impotence. Cleeves and Findley described four patients who developed erectile dysfunction while being treated with bromocriptine. In one 59-year-old man this was paradoxically associated with increased sexual desire. The sexual dysfunction was reversible in all patients either by reducing the dose of bromocriptine or by partial or complete substitution with levodopa. The combination of bromocriptine and levodopa was thought to be responsible for the development of hypersexuality in another case report of drug treatment in Parkinson’s disease.
GnRH is administered to men who have hypogonadism secondary to hypothalamo-pituitary deficiency. It acts by stimulating the pituitary gland to produce gonadotrophins. Two cases of priapism have been reported in 51 hypogonadal men receiving this therapy, presumably as a consequence of rapid increases in testosterone production by the testes. Priapism has also been recorded following testosterone therapy and tamoxifen, which by stimulating gonandotrophins would also be expected to increase serum testosterone levels.