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

Physiologically-based pharmacokinetic modeling of prominent oral contraceptive agents and applications in drug-drug interactions

Considerable interest remains across the pharmaceutical industry and regulatory landscape in capabilities to model oral contraceptives (OCs), whether combined (COCs) with ethinyl estradiol (EE) or progestin-only pill. Acceptance of COC drug-drug interaction (DDI) assessment using physiologically-based pharmacokinetic (PBPK) is often limited to the estrogen component (EE), requiring further verification, with extrapolation from EE to progestins discouraged. There is a paucity of published progestin component PBPK models to support the regulatory DDI guidance for industry to evaluate a new chemical entity's (NCE's) DDI potential with COCs. Guidance recommends a clinical interaction study to be considered if an investigational drug is a weak or moderate inducer, or a moderate/strong inhibitor, of CYP3A4. Therefore, availability of validated OC PBPK models within one software platform, will be useful in predicting the DDI potential with NCEs earlier in the clinical development. Thus, this work was focused on developing and validating PBPK models for progestins, DNG, DRSP, LNG, and NET, within Simcyp, and assessing the DDI potential with known CYP3A4 inhibitors (e.g., ketoconazole) and inducers (e.g., rifampicin) with published clinical data. In addition, this work demonstrated confidence in the Simcyp EE model for regulatory and clinical applications by extensive verification in 70+ clinical PK and CYP3A4 interaction studies. The results provide greater capability to prospectively model clinical CYP3A4 DDI with COCs using Simcyp PBPK to interrogate the regulatory decision-tree to contextualize the potential interaction by known perpetrators and NCEs, enabling model-informed decision making, clinical study designs, and delivering potential alternative COC options for women of childbearing potential.

Ultra-performance liquid chromatography-tandem mass spectrometry assay for determination of plasma nomegestrol acetate and estradiol in healthy postmenopausal women

A highly sensitive and selective ultra-performance liquid chromatography-tandem mass spectrometry method is described for the simultaneous determination of nomegestrol acetate (NOMAC), a highly selective progestogen, and estradiol (E2), a natural estrogen in human plasma. NOMAC was obtained from plasma by solid-phase extraction, while E2 was first separated by liquid-liquid extraction with methyl tert-butyl ether followed by derivatization with dansyl chloride. Deuterated internal standards, NOMAC-d5 and E2-d4 were used for better control of extraction conditions and ionization efficiency. The assay recovery of the analytes was within 90-99%. The analytes were separated on UPLC BEH C₁₈ (50 × 2.1 mm, 1.7 μm) column using a mobile phase comprising of acetonitrile and 3.0 mm ammonium trifluoroacetate in water (80:20, v/v) with a resolution factor (R_s ) of 3.21. The calibration curves were linear from 0.01 to 10.0 ng/mL for NOMAC and from 1.00 to 1000 pg/mL for E2, respectively. The intra- and inter-batch precision was ≤5.8% and the accuracy of quality control samples ranged from 96.7 to 103.4% for both analytes. The practical applicability of the method is demonstrated by analyzing samples from 18 healthy postmenopausal women after oral administration of 2.5 mg nomegestrol acetate and 1.5 mg estradiol film-coated tablets under fasting.

Maintaining physiological testosterone levels by adding dehydroepiandrosterone to combined oral contraceptives: I. Endocrine effects

OBJECTIVE

To determine whether adding dehydroepiandrosterone to combined oral contraceptives (COCs) maintains physiological levels of free testosterone.

STUDY DESIGN

A randomized, double-blind, placebo-controlled, two-way crossover study conducted in 81 healthy women (age range: 20-35 years; Body mass index (BMI) range: 18-35 kg/m²) using oral contraceptives. Androgens, sex hormone-binding globulin (SHBG), estradiol (E2) and estrone (E1) were measured, and free testosterone and the free testosterone index were calculated. Subjects discontinued oral contraceptive use for at least one menstrual cycle before being randomized to receive five cycles of ethinyl estradiol (EE) combined with either levonorgestrel (EE/LNG group) or drospirenone (EE/DRSP group) together with either dehydroepiandrosterone (DHEA) (50 mg/day orally) or placebo. Subsequently, all subjects crossed over to the other treatment arm for an additional five cycles.

RESULTS

Both COCs decreased the levels of all androgens measured. Significant decreases (p<.05) were found with EE/LNG and EE/DRSP for total testosterone (54.5% and 11.3%, respectively) and for free testosterone (66.8% and 75.6%, respectively). Adding DHEA to the COCs significantly increased all androgens compared to placebo. Moreover, including DHEA restored free testosterone levels to baseline values in both COC groups and total testosterone levels to baseline in the EE/LNG group and above baseline in the EE/DRSP group. SHBG concentrations were significantly higher with EE/DRSP compared to EE/LNG (p<.0001). The addition of DHEA did not affect the levels of SHBG.

CONCLUSIONS

Taking COCs reduces total and free testosterone levels and increases SHBG concentrations. By coadministration with DHEA, physiological levels of total and free testosterone are restored while using EE/LNG. With EE/DRSP, only the free testosterone level is normalized by DHEA coadministration.

IMPLICATIONS

A daily oral dose of 50-mg DHEA maintains physiological free and total testosterone levels in women who are using an EE/LNG-containing COC.