Gonadotropin and testosterone secretion in normal human males after stimulation with gonadotropin-releasing hormone (GnRH) or potent GnRH analogs using different modes of application

Buserelin. A review of its pharmacodynamic and pharmacokinetic properties, and clinical profile

The gonadotrophin releasing hormone (GnRH) [luteinising hormone-releasing hormone (LHRH); gonadorelin] agonist buserelin is a promising new agent in the treatment of a variety of disorders in gynaecology and andrology, paediatrics and oncology. While a single dose of buserelin stimulates the release of pituitary gonadotrophins, multiple doses produce reversible pituitary desensitisation, and this specific blockade of gonadotrophin support to the gonads provides the basis for the drug's efficacy in conditions dependent on sex hormone secretion. Thus, buserelin provides comparable efficacy to orchidectomy or high dose estrogens in the treatment of hormone-sensitive prostate cancer and exhibits a lower incidence of adverse effects. During the early phase of treatment it may be particularly useful in combination with antiandrogens. Buserelin also appears promising in hormone-sensitive premenopausal breast cancer. Extensive studies have proven the value of buserelin in endometriosis, where it produces a transient remission with gradual recurrence of the disease on cessation of treatment. Surgical intervention is necessary in severe disease after buserelin-induced involution of the lesions. In patients with uterine leiomyoma, preliminary data suggest that buserelin may be beneficial in rendering surgery more conservative by reducing fibroid size, although it appears unlikely to preclude surgical intervention. The use of buserelin to induce a state of reversible hypogonadotrophism before administration of exogenous gonadotrophins is a promising strategy in the treatment of infertility associated with polycystic ovary syndrome and other conditions of infertility with underlying ovarian dysfunction; such a strategy also clearly enhances the efficiency of in vitro fertilisation programmes. Initial studies suggest its potential usefulness as a female contraceptive when administered intermittently in conjunction with a progestogen. Buserelin represents a first-line treatment of central precocious puberty. In endometriosis the adverse effect profile of buserelin is generally favourable, with hypoestrogenic effects such as hot flushes and vaginal dryness, and decreased libido, predominating. There is no apparent detrimental effect on lipid metabolism. The potential for adverse hypoestrogenic effects on bone mineral content with long term administration remains to be clarified. Thus, the GnRH agonist buserelin represents an advance in the treatment of a variety of gynaecological and andrological as well as paediatric and oncological conditions, infertility and other sex-hormone dependent conditions, with a low incidence of adverse treatment effects.

The biologic activity of a potent analogue of gonadotropin-releasing hormone in normal and hypogonadotropic men

We studied the biologic activity of a long-acting analogue of luteinizing hormone-releasing hormone, D-Trp6-Pro9-NEt-LHRH (LHRHa), in five normal men and four hypogonadotropic men previously unresponsive to natural LHRH. All subjects responded to LHRAa, but there were quantitative and qualitative differences between the normal and hypogonadotropic men. Normal men showed a linear dose-response relation, endogenous gonadal steroid secretion, and an adult pattern of gonadotropin secretion characterized by a high ratio of luteinizing hormone (LH) to follicle-stimulating hormone (FSH). Hypogonadotropic men had improving pituitary responses to each dose of LHRHa (priming response), no demonstrable gonadal steroid secretion, and a prepubertal pattern of gonadotropin release characterized by reversal of the normal ratio of LH to FSH. When compared with native LHRH, LHRHa had an augmented ability to discharge gonadotropins acutely and to sustain their release in normal and hypogonadotropic men.