Do HIV Antiretrovirals and Oral Contraceptives Interact?

Kimberly K. Scarsi, PharmD

Disclosures

November 03, 2014

Question

Are there drug interactions between oral contraceptives and antiretroviral medications for HIV?

Response from Kimberly K. Scarsi, PharmD
Associate Professor, Department of Pharmacy Practice, University of Nebraska Medical Center, Omaha, Nebraska

Women make up about 50% of the global HIV/AIDS epidemic and a growing percentage of the HIV/AIDS epidemic in the United States.[1,2] While the use of condoms is known to decrease the risk for HIV transmission, hormonal contraception remains an important component of women's healthcare. Beyond its use as a family planning method, hormonal contraception is useful for the treatment of other concomitant conditions, including acne, dysmenorrhea, and premenstrual dysphoric disorder. Despite these benefits, the combination of antiretroviral therapy (ART) for HIV and hormonal contraception can be challenging because of drug-drug interactions that may result in increased risk for pregnancy and/or hormone-related complications.[3]

Drug interactions between ART and systemic hormonal contraception are often variable, even within the same antiretroviral drug class, and may result in an increase or decrease of each hormonal component of the contraception. Oral hormonal contraception is widely used and well-studied in combination with ART; however, these studies have consistently demonstrated a risk for drug interactions with some antiretrovirals, which may affect the efficacy and safety of the hormonal contraception.

One study has been published to describe the impact of lopinavir/ritonavir on a contraceptive transdermal patch containing both estrogen and progestin, and similar drug interactions were observed with both the oral and transdermal routes of administration.[4]Medroxyprogesterone depot injections are widely used, with some data to clearly define the drug interactions with ART, and they are currently presumed to be an effective hormonal contraceptive option.[3]Etonogestrel concentrations released from subdermal implants were decreased by 63.4% when given in combination with efavirenz, while lopinavir/ritonavir increased etonogestrel exposure by 52%.[5] Finally, contraceptive hormones administered via a vaginal ring have not yet been characterized in combination with ART.

Patient characteristics and indication for hormonal contraception will aid in the assessment of the drug interaction. For example, it is believed that the contraception efficacy is primarily related to the progestin component of combination hormonal contraception. Therefore, if the primary use of the contraception is for family planning, a decrease in the progestin component may be particularly concerning. On the other hand, if a woman is at risk for estrogen-related toxicities, a drug interaction that results in higher estrogen concentrations should be avoided. Because the specific pharmacologic threshold for both efficacy and toxicity of hormonal contraception is unknown, assessing the impact of drug interactions is particularly challenging.

Because of the variable nature of these drug interactions and the significant differences depending on the specific ART, useful resources for assessing ART in combination with hormonal contraception are the Department of Health and Human Services (HHS) guidelines for treatment of HIV in pregnant women and prevention of perinatal HIV transmission and ART guidelines in HIV-infected adults and adolescents. Both guidelines provide comprehensive, up-to-date tables summarizing the known drug interactions with hormonal contraceptives,[3] drug interactions with ART drug classes,[6] and suggested dosing limits (when available).

While our current knowledge of the efficacy and safety of hormonal contraception in women receiving ART is limited, the combination is an essential component of women's health. The selection of hormonal contraception in HIV-infected women should be similar to starting hormonal contraception in noninfected women, including considering their preferences, indication for therapy, and risk factors for toxicity.[3] However if a known or suspected drug interaction may affect the contraceptive efficacy, a second method of birth control should be recommended, including an intrauterine device or a barrier method.

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