When working with Efavirenz, a non‑nucleoside reverse transcriptase inhibitor (NNRTI) brand‑named Sustiva, used widely in antiretroviral therapy. Also known as Sustiva, it blocks the HIV reverse transcriptase enzyme, slowing virus replication and helping the immune system recover.
HIV, the virus that attacks CD4 cells and leads to AIDS if untreated is the target of Efavirenz‑based regimens. The drug is a cornerstone of NNRTI, a class of antiretrovirals that bind directly to reverse transcriptase and prevent the viral genome from being copied. Because Efavirenz belongs to this class, it shares the rapid‑onset potency of NNRTIs while also inheriting their sensitivity to resistance mutations.
Clinicians typically start Efavirenz in combination with two nucleoside reverse transcriptase inhibitors (NRTIs) as a first‑line regimen for newly diagnosed adults. The standard dose is 600 mg taken on an empty stomach each night, which helps maintain steady blood levels and reduces the risk of breakthrough viremia. Studies show that patients on Efavirenz‑based triple therapy achieve viral suppression in about 85‑90 % of cases within the first year, provided adherence is good.
The drug’s pharmacokinetics are influenced by liver enzymes, especially CYP2B6. Faster metabolizers may need higher doses, while slow metabolizers could experience higher plasma concentrations and stronger side effects. Genetic testing isn’t routine yet, but clinicians often adjust the dose based on tolerance and viral load trends.
Key benefits of Efavirenz include once‑daily dosing, a long half‑life that covers missed doses, and proven efficacy across diverse populations. However, it’s not ideal for pregnant women in the first trimester because of potential neural‑tube defect risks, so alternatives like dolutegravir are preferred in that window.
Common side effects range from mild to moderate. Patients often report vivid dreams, insomnia, or dizziness during the first few weeks. Neuropsychiatric symptoms, such as anxiety or mood changes, affect roughly 20 % of users, so clinicians should screen for mental health history before prescribing. Most side effects wane after the initial adjustment period, but persistent problems may require a switch to another NNRTI or an integrase inhibitor.
Drug interactions are a major consideration. Efavirenz induces CYP3A4 and CYP2C9, lowering the levels of many co‑administered drugs, including certain contraceptives, warfarin, and some antiepileptics. Conversely, strong inhibitors of CYP2B6 can raise Efavirenz concentrations, increasing the likelihood of toxicity. Patients should inform their healthcare provider about over‑the‑counter supplements—St. John’s wort, for example, can dramatically reduce Efavirenz effectiveness.
Resistance develops when the virus acquires mutations like K103N or Y188L in the reverse transcriptase gene. Once resistance occurs, Efavirenz loses most of its activity, and clinicians must switch to a regimen with a higher barrier to resistance, such as an integrase strand transfer inhibitor. Regular viral load monitoring helps catch resistance early, allowing timely regimen changes.
Below you’ll find a curated collection of articles that dig deeper into Efavirenz dosing strategies, side‑effect management, interaction checks, and the latest research on resistance patterns. Whether you’re a patient looking for practical tips or a practitioner seeking updated guidelines, the resources here will give you the insight you need to make informed decisions about Efavirenz therapy.
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