GnRH analogs are globally used for assisted reproduction in infertile patients. To date, in healthy female volunteers the pharmacokinetic and pharmacodynamic profiles of cetrorelix when administered in a single dose have been investigated in studies conducted using doses of 1, 3 and 5 mg. Studies performed in premenopausal female volunteers confirmed that cetrorelix rapidly suppresses luteinizing hormone (LH) and estradiol and shows dose-dependent prolongation of the duration of LH suppression. However, there have been few reports of studies of the relationship between the cetrorelix dosage and its effect on LH surge. In the present study, we investigated the effect of cetrorelix on LH surge when this drug was administered in single doses of 1, 2 and 3 mg.

To evaluate that effect on LH surge, we investigated the efficacy of cetrorelix in delaying the start of the LH surge in comparison with the control menstrual cycle when saline was administered, and also examined the mode of disappearance of pulsatile LH secretion during the cetrorelix administration menstrual cycle.

Inclusion Criteria:

• a BMI of 18 years old and <18 and 25 years old and >25
• menstrual cycles was within the range of 25~31 days

Exclusion Criteria:

• use of a drug (e.g., oral contraceptives, drugs for treatment of hyperprolactinemia, GnRH agonists, sex steroid hormones, psychoactive drugs, etc.)
• serious disease of the endocrine system, liver, kidney, heart, lung, digestive system, etc.
• a generalized drug allergy