Modafinil, sold under the brand name Provigil, is used to treat sleep disorders such as narcolepsy and obstructive sleep apnea. Provigil is a stimulant that enhances daytime wakefulness but is known to interact with many prescription drugs, including hormonal birth control methods. It is thought to do this by inhibiting enzymes, called cytochromes, that break down drugs, thereby increasing circulating levels of certain drugs. This is the only known effect of Provigil on birth control medicines.
Clinical Trials
Ethinyl estradiol is the main active ingredient in almost all hormonal birth control, including birth control pills such as Ortho Tri-Cyclen, Yaz, Demulen and Seasonale; the patch Ortho Evra; and the vaginal ring Nuva Ring. Ethinyl estradiol's effectiveness is reduced when Provigil is taken simultaneously, leading to an increased risk of pregnancy. In a 2002 study at Cephalon by Philmore Robertson, Jr., and colleagues, women given Provigil 200 mg a day for 7 days, and then 400 mg a day for 21 days had a decrease in the maximum blood concentration of ethinyl estradiol as well as in the total amount of blood concentration of ethinyl estradiol over 24 hours.
Mechanism
Provigil is known to change how certain cytochromes work. Different cytochromes break down different types of drugs in the body. Ethinyl estradiol is broken down by cytochrome CYP450 3A4 in the liver. Provigil increases activity of CYP450 3A4, leading to decreased levels of ethinyl estradiol in the body. Lowered levels of ethinyl estradiol can lead to increased chances of conception.
Precautions
Users of Provigil and hormonal birth control should use a secondary, non-hormonal method of contraception such as condoms, spermicide, diaphragm or intrauterine devices to prevent pregnancy for the duration of Provigil use and one month after. Another option may be to use birth control pills that contain only progestogen instead of ethinyl estradiol, such as Micronor, or a non-estrogen based injectable such as Depo Provera. Progestogen may not be a target of the cytochromes whose activities are changed by Provigil, and thus blood levels of progestogen may be normal in Provigil users.
References
- Provigil: Prescribing Information
- "Essential Psychopharmacology: The Prescriber's Guide"; S. M. Stahl; 2006
- "Effect of Modafinil on the Pharmacokinetics of Ethinyl Estradiol and Triazolam in Healthy Volunteers"; Clinical Pharmacology and Therapeutics; Philmore Robertson, Jr., et al.; January 2002
