ARV interactions with hormonal contraception

A major problem for most hormonal contraceptive products is that many anti-HIV medications interact with them, reducing their efficacy (see table).

This includes the non-nucleoside reverse transcriptase inhibitors, nevirapine (Viramune) and efavirenz (Sustiva) and the class of protease inhibitor drugs with the exception of indinavir (Crixivan).

There are two ARV [1]A medication or other substance which is active against retroviruses such as HIV. that increase blood levels of contraceptives: indinavir and delavirdine, however delavirdine is not licensed in Australia and indinavir is an increasingly unpopular drug owing to the complexities of its dosing requirements and its side effects.

The only hormonal device that states it is not affected by medicines taken at the same time is the hormone-release device that is inserted into the womb, known as the intrauterine system (IUS) or Mirena.

ARV that reduce levels of hormonal contraceptives

Drug	Affect on hormonal contraception	Advice
Nelfinavir (Viracept)	Reduces oestrogen and progesterone content. Reduces norethindrone (progesterone) levels by 18% and ethynyl estradiol (oestrogen) levels by 47%.	Do not use with hormonal contraceptives - significant association with contraceptive failure
Ritonavir (Norvir)	Reduces oestrogen blood levels. Reduces ethinyl estradiol (oestrogen) levels by 32-40%.	Dosage increase or alternative contraception used
Efavirenz (Stocrin)	Not fully studied	Do not use with hormonal contraceptives. In a retrospective study of 2053 women there were two apparent contraceptive failures for women taking efavirenz. As efavirenz is also associated with birth defects, contraceptive failure is particularly important to avoid.
Nevirapine (Viramune)	Significant decrease in blood levels of both oestrogens and progesterones. Based on evidence examining a single dose of an oral contraceptive containing ethinyl estradiol (0.035 mg) and norethindrone (1.0 mg).	Use barrier contraception in addition or as an alternative to hormonal contraception
Saquinavir (Invirase, Fortovase)	Reduces oestrogens. One of the 11 women in a retrospective study who conceived while on hormonal contraception was taking saquinavir (Clark 2204).	Do not use with oestrogen-based contraceptives (combined Pill or patch)
Kaletra (lopinavir/ritonavir)	Lopinavir reduces both oestrogens and progesterones; ritonavir reduces oestrogens	Use barrier contraception in addition or as an alternative to hormonal contraception
Atazanavir (Reyataz)	Increases progesterone and oestrogen concentrations; “ May affect safety and effectiveness [2](Of a drug or treatment). The maximum ability of a drug or treatment to produce a result regardless of dosage. A drug passes efficacy trials if it is effective at the dose tested and against the illness for which it is prescribed. In the standard procedure, Phase II clinical trials gauge efficacy, and Phase III trials confirm it.” of oral contraception or patch.	If used in combination with ritonavir, may decrease concentrations of contraceptive hormones – alternative contraception preferred.