Plasma gonadotropin and gonadotropin-releasing hormone levels after intranasal administration of gonadotropin releasing hormone.

Intranasal administration of gonadotropin hormone (GnRH) in doses ranging from 2-4 mg produced a consistently prolonged LH response in patients with secondary amenorrhea. In 4 cases, a delayed secondary rise occurred. A similarly prolonged FSH response was observed in the majority of patients. Six hours after intranasal GnRH, FSH and LH values were well above basal levels and were higher than those observed at a similar interval after intravenous GnRH. Plasma GnRH levels after intranasal administration failed to achieve the high peaks found after the intravenous route but maintained elevated levels for at least an hour and often longer. Despite the much lower plasma GnRH levels, intranasal GnRH produced a sustained effect on LH and FSH secretion, greater than GnRH given by the intravenous route.