- What is efavirenz, and how does it work (mechanism of action)?
- What are the uses 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 efavirenz, and how does it work (mechanism of action)?
Efavirenz is an oral medication that is used for the treatment of infections associated with the human immunodeficiency virus (HIV). Efavirenz is in a class of drugs called reverse transcriptase inhibitors, which also includes zalcitabine (Hivid), zidovudine (Retrovir), didanosine (Videx), and lamivudine (Epivir). It is in a subclass of reverse transcriptase inhibitors referred to as non-nucleoside reverse transcriptase inhibitors that includes nevirapine (Viramune), and delavirdine (Rescriptor). During infection with HIV, the HIV virus multiplies within the body's cells. The newly-formed viruses then are released from the cells and spread throughout the body where they infect other cells. In this manner, the infection continually spreads to new, uninfected cells that the body is continually producing, and HIV infection is perpetuated. When producing new viruses, the HIV virus must manufacture new DNA for each virus. Reverse transcriptase is the enzyme that the virus uses to form new DNA. Efavirenz directly inhibits the activity of reverse transcriptase and blocks the production of DNA and new viruses. Efavirenz does not kill existing HIV virus and it is not a cure for HIV. Efavirenz was approved by the FDA in 1998.
What brand names are available for efavirenz?
Is efavirenz available as a generic drug?
GENERIC AVAILABLE: No
Do I need a prescription for efavirenz?
What are the side effects of efavirenz?
The most common side effects of efavirenz are:
Other side effects include
- muscle pain (myalgia),
- abnormal heartbeats,
- liver failure,
- increased cholesterol
- increased triglyceride levels.
- abnormal dreams,
- hallucinations, and
- difficulty concentrating.
Serious psychiatric adverse effects such as depression, suicidal thoughts, manic reactions, and aggressive behavior have been reported in patients taking efavirenz. Immune reconstitution syndrome which is an inflammatory response to infection may occur in patients treated with combination antiretroviral therapy.
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 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.
Is efavirenz safe to take if I'm pregnant or breastfeeding?
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.
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.
What else should I know about efavirenz?
What preparations of efavirenz are available?
Capsules: 50 and 200 mg. Tablet: 600 mg.
How should I keep efavirenz stored?
Efavirenz should be stored at room temperature, 15 C to 30 C (59 F to 86 F).
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Efavirenz (Sustiva) is a drug prescribed to treat infections associated with the human immunodeficiency virus (HIV). Review side effects, dosage, drug interactions, warnings and precautions, and pregnancy safety information prior to taking this drug.
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Related Disease Conditions
Human Immunodeficiency Virus (HIV)
HIV (human immunodeficiency virus) infection left untreated causes AIDS (acquired immunodeficiency syndrome). The human immunodeficiency virus (HIV) is a type of virus called a retrovirus, which can infect humans when it comes in contact with tissues that line the vagina, anal area, mouth, or eyes, or through a break in the skin. HIV infection is generally a slowly progressive disease in which the virus is present throughout the body at all stages of the disease. Three stages of HIV infection have been described. The initial stage of infection (primary infection), which occurs within weeks of acquiring the virus, often is characterized by the flu- or mono-like illness that generally resolves within weeks. The stage of chronic asymptomatic infection (meaning a long duration of infection without symptoms) lasts an average of eight to 10 years without treatment. The stage of symptomatic infection, in which the body's immune (or defense) system has been suppressed and complications have developed, is called the acquired immunodeficiency syndrome (AIDS). The symptoms are caused by the complications of AIDS, which include one or more unusual infections or cancers, severe loss of weight, and intellectual deterioration (called dementia). When HIV grows (that is, by reproducing itself), it acquires the ability to change (mutate) its own structure. These mutations enable the virus to become resistant to previously effective drug therapy. The goals of drug therapy are to prevent damage to the immune system by the HIV virus and to halt or delay the progress of the infection to symptomatic disease. Therapy for HIV includes combinations of drugs that decrease the growth of the virus to such an extent that the treatment prevents or markedly delays the development of viral resistance to the drugs. The best combination of drugs for HIV are those that effectively suppress viral replication in the blood and also are well tolerated and simple to take so that people can take the medications consistently without missing doses.
AIDS (Acquired Immunodeficiency Syndrome)
AIDS is the advanced stage of HIV infection. Symptoms and signs of AIDS include pneumonia due to Pneumocystis jiroveci, tuberculosis, toxoplasmosis, seizures, weakness, meningitis, yeast infection of the esophagus, and Kaposi's sarcoma. Anti-retroviral therapy (HAART) is used in the treatment of AIDS.
Treatment & Diagnosis
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Medications & Supplements
- Drugs: Questions to Ask Your Doctor or Pharmacist about Your Drugs
- Drug Interactions
- What Are NNRTIs In Antiretroviral Therapy for HIV Infection?
- Retrovir (zidovudine, ZDV, formerly called AZT)
- lamivudine (3tc) (Epivir; Epivir HBV)
- didanosine (Videx, Videx EC)
- delavirdine (Rescriptor)
- nevirapine (Viramune, Viramune XR)
- Combivir (lamivudine and zidovudine)
- Side Effects of Sustiva (efavirenz)
- stavudine (Zerit)
Prevention & Wellness
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Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.