Prediction of nomegestrol acetate pharmacokinetics in healthy female adolescents and adults by whole-body physiology-based pharmacokinetic modelling and clinical validation

ObjectiveNomegestrol acetate (NOMAC), a selective progestogen, and 17β-estradiol (E2), which is identical to endogenous oestrogen, are components of a new monophasic combined oral contraceptive - NOMAC/E2. This study aimed to compare pharmacokinetics (PK) of NOMAC in adolescent and adult women following a single dose of NOMAC/E2.Study designHealthy postmenarcheal adolescent (14-17 years) and adult (18-50 years) women received a single dose of NOMAC/E2 (2.5 mg/1.5 mg) in this single-centre, open-label, parallel-group Phase 1 study (EudraCT# 2008-002142-38). Blood samples were obtained for PK analysis, and concentrations of NOMAC, E2 and its metabolite estrone (E1) were determined for up to 129 h following dosing to obtain PK data. An independent whole-body physiology-based pharmacokinetic (WB-PBPK) simulation model of NOMAC based on an independent Phase 3 dataset was used to scale NOMAC concentration-time plots to adolescents.ResultsOverall, 52 women were screened, of whom 30 (15 adolescents and 15 adults) were enrolled. No statistically significant differences were observed between the adolescent and adult groups for the clinically evaluated NOMAC PK parameters [maximum concentration (Cmax), area under the curve (AUC) and half-life (t1/2)]. The PK of E2 and E1 showed extensive overlap between both age groups. The WB-PBPK model accurately predicted NOMAC AUC and Cmax values in both groups.ConclusionsNo differences were observed in the clinically evaluated PK parameters for NOMAC between adolescent and adult women after a single dose of NOMAC/E2. The WB-PBPK model accurately predicted NOMAC PK data (EudraCT# 2008-002142-38).ImplicationsPK studies in adolescents are challenging because of ethical considerations. The whole-body physiology-based model described here complements classic noncompartmental and population PK approaches. The utility of this method is its ability to expand to adolescent postmenarcheal girls by using virtual postmenarcheal adolescent population data and applying physiological scaling.