efavirenz, Sustiva (cont.)
Omudhome Ogbru, PharmD
Omudhome Ogbru, PharmD
Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.
Medical and Pharmacy Editor:
GENERIC AVAILABLE: No
PREPARATIONS: Capsules: 50 and 200 mg. Tablet: 600 mg.
STORAGE: Efavirenz should be stored at room temperature, 15 C to 30 C (59 F to 86 F).
PRESCRIBED FOR: Efavirenz is prescribed for the treatment of HIV infection in combination with other anti-HIV drugs.
DOSING: The recommended dose for adults is 600 mg daily. Efavirenz must be administered in combination with other anti-HIV drugs because the HIV virus quickly becomes resistant to treatment when efavirenz is used alone. Efavirenz should be administered on an empty stomach to improve absorption, preferably at bedtime.
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 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.
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