Overview

Levonorgestrel (LNG) is a synthetic progestogen similar to Progesterone used in contraception and hormone therapy. Also known as Plan B, it is used as a single agent in emergency contraception, and as a hormonal contraceptive released from an intrauterine device, commonly referred to as an IUD. Some of these devices are known as Jaydess, Kyleena, and Mirena. A subdermal implant of levonorgestrel that slowly releases the hormone over a long-term period is also available. In addition to the above uses, levonorgestrel is used as a component of long-term combination contraceptives. Globally, levonorgestrel is the most commonly used emergency contraceptive. It was initially granted FDA approval in 1982 and was the first emergency contraceptive containing only progesterone, showing high levels of efficacy and a lack of estrogenic adverse effects when compared to older emergency contraceptive regimens.

Indication

Emergency contraception Levonorgestrel, in the single-agent emergency contraceptive form, is indicated for the prevention of pregnancy after the confirmed or suspected failure of contraception methods or following unprotected intercourse. It is distributed by prescription for patients under 17, and over the counter for those above this age. This levonorgestrel-only form of contraception is not indicated for regular contraception and must be taken as soon as possible within 72 hours after intercourse. It has shown a lower efficacy when it is used off label within 96 hours. Long-term contraception or nonemergency contraception In addition to the above indication in emergency contraception, levonorgestrel is combined with other contraceptives in contraceptive formulations designed for regular use, for example with ethinyl estradiol. It is used in various hormone-releasing intrauterine devices for long-term contraception ranging for a duration of 3-5 years. Product labeling for Mirena specifically mentions that it is recommended in women who have had at least 1 child and can be indicated for the prevention of pregnancy for up to 8 years. A subdermal implant is also available for the prevention of pregnancy for up to 5 years. Hormone therapy and off-label uses Levonorgestrel is prescribed in combination with estradiol as hormone therapy during menopause to manage vasomotor symptoms and to prevent osteoporosis.Off-label, levonorgestrel may be used to treat menorrhagia, endometrial hyperplasia, and endometriosis.

Associated Conditions

Endometrial Hyperplasia
Endometriosis
Heavy Menstrual Bleeding
Hypermenorrhea
Postmenopausal Osteoporosis
Pregnancy
Moderate Menopausal Vasomotor Symptoms
Severe Vasomotor Symptoms Associated With Menopause

Research Report

Published: Jul 31, 2025

Levonorgestrel (DB00367): A Comprehensive Monograph on its Chemistry, Pharmacology, Clinical Utility, and Development

Executive Summary

Levonorgestrel is a second-generation synthetic progestin that stands as a cornerstone of modern hormonal therapy and contraception. As the biologically active levorotatory enantiomer of norgestrel, it exerts potent progestational and androgenic effects, primarily by inhibiting ovulation through the suppression of the mid-cycle luteinizing hormone (LH) surge. Its remarkable versatility is demonstrated by its incorporation into a vast array of formulations, each tailored to a specific clinical need. These range from high-dose oral tablets for emergency contraception (EC) to low-dose daily oral pills (both combination and progestin-only), and long-acting reversible contraceptives (LARCs) such as subdermal implants and intrauterine devices (IUDs). Beyond contraception, levonorgestrel-releasing IUDs are approved for treating heavy menstrual bleeding and are used off-label for managing conditions like endometriosis and endometrial hyperplasia.

The pharmacological profile of levonorgestrel is well-characterized, but its clinical performance is significantly influenced by patient-specific factors, most notably body mass index (BMI). Pharmacokinetic studies have definitively shown that in women with obesity, increased volume of distribution and metabolic clearance lead to substantially lower plasma concentrations, providing a clear mechanistic basis for the observed reduction in EC efficacy in this population. This has highlighted a critical unmet need for evidence-based dosing strategies in individuals with high BMI.

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Clinical Trials

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Title	Posted	Study ID	Phase	Status	Sponsor
Study Evaluating Levonorgestrel and Ethinyl Estradiol in Oral Contraception	2005/11/04	NCT00248963	Phase 3	Completed	Wyeth is now a wholly owned subsidiary of Pfizer
Study Evaluating Levonorgestrel and Ethinyl Estradiol for Oral Contraception	2005/10/28	NCT00245921	Phase 3	Completed	Wyeth is now a wholly owned subsidiary of Pfizer
Human Ovarian Follicular Dynamics and Emergency Contraception	2005/09/20	NCT00204451	Phase 4	Completed	University of Saskatchewan
Dose-finding Study for the Ultralow-dose Levonorgestrel Intrauterine Contraceptive System (LCS)	2005/09/16	NCT00185380	Phase 2	Completed	Bayer
Effects of St. John's Wort on the Oral Contraceptive Hormone Levonorgestrel	2005/08/19	NCT00131885	Phase 4	Completed	University of Utah

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