Pharmacokinetic and pharmacodynamic characteristics of ganirelix (Antagon/Orgalutran). Part I. Absolute bioavailability of 0.25 mg of ganirelix after a single subcutaneous injection in healthy female volunteers.

OBJECTIVE: To assess the absolute bioavailability of ganirelix (Antagon/Orgalutran; NV Organon, Oss, the Netherlands) after a single SC injection.
DESIGN: Randomized, crossover, pharmacokinetic study.
SETTING: Phase I clinical research unit. PATIENT(S): Nineteen healthy female volunteers of reproductive age. INTERVENTION(S): Two separate injections of 0.25 mg of ganirelix were given, one subcutaneously and one intravenously, with a washout period of 1 week between injections. Blood samples were taken for assessment of serum ganirelix concentrations, and blood pressure, heart rate, and adverse events were monitored. MAIN OUTCOME MEASURE(S): Pharmacokinetic parameters. RESULT(S): Fifteen subjects were evaluated. The mean concentration-time profile after SC administration was comparable to that after IV administration. The mean (+/- SD) peak concentration and time of occurrence after SC administration were 14.8+/-3.2 ng/mL and 1.1+/-0.3 hours, respectively. The mean (+/- SD) half-lives after IV administration and SC administration were highly similar (12.7+/-3.7 hours and 12.8+/-4.3 hours, respectively). Mean (+/- SD) AUC0-infinity (area under the concentration-time curve) values of 105+/-11 ng/mL x hours and 96+/-12 ng/mL x hours were calculated for IV administration and SC administration, respectively, resulting in an absolute mean (+/- SD) bioavailability of 91.3%+/-6.7%. Both treatments were well tolerated. CONCLUSION(S): Ganirelix is absorbed rapidly and extensively after SC administration, resulting in a high absolute bioavailability of >90%.

RCT Entities:   Population Interventions Outcomes