efavirenz, Sustiva (cont.)

Pharmacy Author:
Medical and Pharmacy Editor:

DRUG INTERACTIONS: Efavirenz has many drug interactions because many drugs affect its breakdown and elimination by the liver. Efavirenz also affects the breakdown of other drugs by the liver. The following are some examples of drugs that interact with efavirenz.

Triazolam (Halcion), midazolam (Versed), bepridil (Vascor), pimozide (Orap), and ergot derivatives (for example, ergotamine, dihydroergotamine) should not be combined with efavirenz because efavirenz increases blood levels of these drugs, potentially causing serious adverse effects. St. John's wort should not be combined with efavirenze because it reduces blood levels of efavirenz, leading to possible loss of effectiveness.

Efavirenz increases the breakdown of saquinavir (Invirase) and indinavir (Crixivan). This leads to lower drug concentrations in the body and reduces the effect of saquinavir and indinavir.

Efavirenz increases the concentration of ritonavir (Norvir) while Ritonavir increases the concentration of efavirenz. Increased drug concentrations may result in more frequent or more serious side effects.

PREGNANCY: There are no adequate studies in pregnant women. Data from an antiretroviral pregnancy registry revealed birth defects in 17 of 604 live births in women who took efavirenz during the first trimester.

NURSING MOTHERS: It is not known whether efavirenz is excreted in human breast milk. HIV-infected mothers should not breastfeed because of the risk of transmitting HIV to an infant that is not infected.

Medically reviewed by Eni Williams, PharmD

Reference: FDA Prescribing Information


Medically Reviewed by a Doctor on 6/17/2015


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