This study aims to validate prior pharmacokinetic research with combined oral contraceptive pill users that supports utilizing a 24-hour trough concentration as an accurate proxy for the intensive pharmacokinetic parameter of area under the curve (gold standard pharmacokinetics). The original pharmacokinetic studies were performed with a levonorgestrel-containing oral contraceptive pill and we aim to duplicate those findings with a desogestrel-containing oral contraceptive pill.

Enrolled participants will be started on a standard pack of desogestrel-containing oral contraceptive pills and undergo an intensive pharmacokinetic study visit on day 21 of the pill pack. This will entail 11 serial blood draws and a final blood draw the next day at 24 hours post-pill intake to measure and calculate a pharmacokinetic area under the curve for both the estrogen and progestin components of the pill. We will then correlate the 24-hour trough measurement to the area under the curve measures to determine the correlation of these measurements.

Inclusion Criteria:

• Healthy females aged 18-45 years
• Body-mass index ≥18.5kg/m2
• Willing to abstain from medications and supplements known to induce/inhibit CYP3A4 during the study
• Normal blood pressure measurement at screening (systolic <140mmHg, diastolic <90mmHg)
• Negative urine pregnancy test at screening

Exclusion Criteria:

• Currently taking any known CYP3A4 inducers/inhibitors
• Medical conditions that affect liver function (e.g. hepatitis, cirrhosis)
• Any contraindications to estrogen-containing contraception (based on any category 3 or 4 recommendations from the CDC MEC guidelines)
• Use of an injectable contraceptive method within the last 6 months or current use of an ENG contraceptive implant
• Childbirth within the last 6 months
• Known allergy or insensitivity to combined oral contraceptive pills

22 days