Related Experiment Video
Updated: Jun 6, 2026

Ovariectomy and 17β-estradiol Replacement in Rats and Mice: A Visual Demonstration
Published on: June 7, 2012
Steady-state pharmacokinetics of an extended-regimen oral contraceptive with continuous estrogen
Charles E DiLiberti1, Christine M O'Leary, Christopher H Hendy
1Teva Pharmaceutical Industries, Ltd (formerly Barr Laboratories, Inc. which includes the subsidiaries Barr Laboratories, Inc. and Duramed Pharmaceuticals) Horsham, PA 19044, USA.
Background:
This study was conducted to evaluate the steady-state blood concentrations and potential accumulation of levonorgestrel (LNG) and ethinyl estradiol (EE) administered for up to 84 days and EE alone for 7 additional days as an extended-regimen 91-day oral contraceptive (OC).
Study Design:
An open-label, single-site study was conducted in 30 healthy female volunteers. Subjects received daily doses of 0.15 mg LNG/0.03 mg EE for 84 consecutive days followed by 0.03 mg EE alone for 7 days. Pharmacokinetic (PK) monitoring was conducted on Days 1, 21, 84 and 91.
Results:
The observed plasma concentrations of LNG after 84 days and of EE after 84 and 91 days were comparable to the steady-state concentrations observed at 21 days. Pharmacokinetic parameters over the 24-h dosing period were similar at all time points measured after achieving steady-state plasma concentrations.
Conclusion:
This study demonstrated that an extended-regimen OC providing 84 days of LNG/EE and 7 days of EE alone has a PK profile similar to a 28-day conventional OC regimen and does not result in any additional accumulation of these hormones.
Related Concept Videos
Dosage Regimen: Multiple Oral Dosage
Steady State Concentration
Most drugs are administered in repeated doses at fixed intervals or through continuous intravenous...
Oral Drug Delivery Systems: Continuous-Release Systems
Pharmacokinetic–Pharmacodynamic Relationship: Duration of Dose-Effect Relationship
Drug Accumulation During Multiple Dosing: Intermittent IV Infusions
IV Infusion to Oral Dosing: Conversion Methods
