Letter: Intranasal administration of synthetic gonadotrophin-releasing hormone

Vaginal absorption of a potent luteinizing hormone-releasing hormone analog (leuprolide) in rats I: absorption by various routes and absorption enhancement

The absorption of a potent luteinizing hormone-releasing hormone analog (leuprolide) through different routes was evaluated by determining the ovulation-inducing activity in diestrous rats. Vaginal administration showed the greatest potency among nonparenteral routes and was followed successively by rectal, nasal, and oral administration. Mixed micellar solution with monoolein-bile acids improved the intestinal absorption of leuprolide, and nasal absorption was enhanced by adding sodium glycocholate, surfactin, or polyoxyethylene 9 lauryl ether, but these bioavailabilities were still insufficient. The vaginal absorption was enhanced by organic acids: citric, succinic, tartaric, and glycocholic; the absolute bioavailability increased to approximately 20%. The vaginal absorption from jellies, as practical dosage forms, yielded sufficient activity of leuprolide, but absorption was slightly reduced with highly polar polymers or with higher concentrations of polymers. It was concluded that vaginal administration of leuprolide can be a rational dosage method for a long-term antitumor therapy.

Assessment of pituitary response to nasal application of synthetic gonadotropin-releasing hormone in men

An attempt has been made to assess the pituitary response to the nasal application of synthetic gonadotropin-releasing hormone (GnRH) in three oligospermic and two azoospermic men. Intranasal administration of 3 mg of GnRH in aqueous or natural plant gum solution produced a pituitary response pattern similar to that produced by the intramuscular injection of 100 microng, with respect to plasma concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). No technical difficulties or side effects were observed. GnRH in a nasal drop preparation seems to be effective in releasing LH and FSH in men. These findings may have a practical application in those cases where long-term therapy with the hormone is indicated.