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Effects of St. John's Wort on the Oral Contraceptive Hormone Levonorgestrel

Information source: University of Utah
ClinicalTrials.gov processed this data on August 23, 2015
Link to the current ClinicalTrials.gov record.

Condition(s) targeted: Contraception

Intervention: Placebo Control (Placebo Herb) (Dietary Supplement); St. John's Wort (Dietary Supplement); Levonorgestrel (Drug)

Phase: Phase 4

Status: Completed

Sponsored by: University of Utah

Official(s) and/or principal investigator(s):
Patricia A. Murphy, DrPH, Principal Investigator, Affiliation: College of Nursing, University of Utah

Summary

This study will determine the effects of St. John's wort, a common herbal remedy, on metabolism of the female contraceptive hormone levonorgestrel.

Clinical Details

Official title: Effects of St. John's Wort on Levonorgestrel

Study design: Allocation: Randomized, Endpoint Classification: Pharmacokinetics/Dynamics Study, Intervention Model: Parallel Assignment, Masking: Single Blind (Subject), Primary Purpose: Treatment

Primary outcome:

Area Under the Concentration Versus Time Curve for 0 to 24 Hours After Drug Administration, Done Between Days 9 and 12 of the Menstrual Cycle at Time 1 (Before) and Time 2 (During Treatment With St. John's Wort or Placebo)

Number of Participants With Progesterone Levels Above 3.0 ng/ml at Time 1 (Baseline) and Time 2 (After Intervention With St John's Wort or Placebo).

Clearance (L/hr) of Levonorgestrel Over 24 Hours for Each Dosage Group and Each Study Session.

Secondary outcome:

Mean Levels of Follicle-stimulating Hormone Drawn at Weekly Intervals Until Next Menses

Mean Levels of Estradiol-17b (E2) Drawn at Weekly Intervals Until Next Menses

Mean Levels of Luteinizing Hormone, Drawn at Weekly Intervals Until Next Menses

Detailed description: In the last decade, St. John's wort has become one of the most commonly used botanicals. Levonorgestrel is a form of progesterone, a female hormone involved in conception. It can be given as both a pill and an injection and is used for contraception and for the treatment of endometriosis. However, evidence suggests that St. John's wort may reduce the effectiveness of the contraceptive hormone levonorgestrel. This study will determine whether interactions between St. John's wort and levonorgestrel reduce the effectiveness of the hormone. This study will also determine whether a higher dose of levonorgestrel will override the effects of St. John's wort. All participants will receive a single dose of levonorgestrel between Days 9 and 12 of their first menstrual cycle after entering this study. Blood and urine collection will occur immediately after the levonorgestrel is given and every week until participants' next menstrual cycle to determine the levels of reproductive hormones in participants' bodies. At the beginning of participants' next menstrual cycle, they will be randomly assigned to one of four groups and receive either St. John's wort or placebo for 6 weeks. Group 1 will receive a placebo; Groups 2 and 3 will receive a standard dose of St. John's wort (900 mg per day); and Group 4 will receive an increased dose of St. John's wort (1500 mg per day). After 6 weeks, Groups 1, 2, and 4 will receive 150 mcg levonorgestrel; and Group 3 will receive 225 mcg levonorgestrel. Blood and urine collection will occur immediately after levonorgestrel is given and every week until participants' next menstrual cycle.

Eligibility

Minimum age: 18 Years. Maximum age: 30 Years. Gender(s): Female.

Criteria:

Inclusion Criteria:

- Body mass index (BMI) between 20 and 25

- Regular menstrual cycles for at least 3 months prior to study entry

Exclusion Criteria:

- Current use of foods, herbs, vitamins, over-the-counter supplements, or any

medications that could alter pharmacokinetics of other drugs

- Medical contraindications to the use of contraceptives

Locations and Contacts

University of Utah, Salt Lake City, Utah 84112, United States
Additional Information

Related publications:

Murphy PA, Kern SE, Stanczyk FZ, Westhoff CL. Interaction of St. John's Wort with oral contraceptives: effects on the pharmacokinetics of norethindrone and ethinyl estradiol, ovarian activity and breakthrough bleeding. Contraception. 2005 Jun;71(6):402-8.

Starting date: August 2005
Last updated: July 15, 2015

Page last updated: August 23, 2015

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