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- What is efavirenz, and how does it work (mechanism of action)?
- What brand names are available for efavirenz?
- Is efavirenz available as a generic drug?
- Do I need a prescription for efavirenz?
- What are the side effects of efavirenz?
- What is the dosage for efavirenz?
- Which drugs or supplements interact with efavirenz?
- Is efavirenz safe to take if I'm pregnant or breastfeeding?
- What else should I know about efavirenz?
What is the dosage for efavirenz?
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.
Which drugs or supplements interact with efavirenz?
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.
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