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Approved by the United States’ Food and Drug Administration on September 21, 1998, Efavirenz is only the fourteenth approved retroviral drug.

Efavirenz is a potent drug used to treat human immunodeficiency virus (HIV) type 1. However, Efavirenz can never be taken as the lone treatment for HIV. It is always taken in combination with other drugs as part of a highly active antiretroviral therapy.

Efavirenz’s effects lies in its ability to inhibit the reverse transcriptase enzyme (ribonucleic acid) from transcribing or copying the viral RNA (ribonucleic acid) into the patient’s DNA (deoxyribonucleic acid). In speaking of RNAs and DNAs, it means that the HIV works on the most fundamental level of man’s biology, it’s own genetic building block. As such, to be effective Efavirenz has to work on this level, too.

More specifically, Efavirenz is categorized under the non-nucleoside reverse transcriptase inhibitor (NNRTI) kind of antiretrovirals. This means that unlike nucleoside RTIs, Efavirenz works by letting its reverse transcriptase inhibitor block the viral enzyme by attaching to the enzyme’s pocket, the NNRT pocket.

By binding within the viral enzyme’s pocket, Efavirenz prevents the viral enzyme from copying the viral RNA to the patient’s DNA. This way the virus is unable to spread throughout the body. SO, essentially, Efavirenz cannot get completely get rid of the virus. Its effect will only ensure that the virus will spread at a very, very slow rate.

Usually, patients are advised to take a single tablet everyday. The dosage is usually 600 mg and is taken at bedtime and on an empty stomach. This is done so as to reduce any possible adverse neurological and psychiatric side effects. However, if the patient is also undergoing treatment for tuberculosis and is taking rifampicin, the dosage of Efavirenz is increased to 800 mg daily.

As mentioned earlier, Efavirenz is never taken as the sole treatment for HIV. Rather, the administration of Efavirenz is usually coupled with lamivudine/zidovudine or tenofovir/emtricitabine. Taken with these two, Efavirenz’ effects will be maimized.

However, despite the fact that the patient is required to drink only one Efavirenz pill each day, the medication can be quite pricey. In fact, in industrialized countries, a month’s worth of the 600 mg pill is equivalent to almost $ 1400 USD. Since Efavirenz works at the body’s most fundamental level and since it works against a very powerful virus, the patient taking it must take precaution. More so, if the patient is a woman. First of all, if you are taking Efavirenz, you are not allowed to get pregnant. You must double your contraceptive measures by taking a barrier method such as the condom and coupling it with some sort of pill or injection. Conceiving a baby at this point in treatment may lead to a malformed fetus. Moreover, you are also not allowed to breastfeed since you may introduce the medicine to the infant’s system.

As a potent drug, Efavirenz does pose certain possible side effects. It can induce negative psychiatric effects. It can cause the patient to develop insomnia, memory loss, confusion and depression. On a physical level, it can cause dizziness and headaches.

Some side effects are indications of much graver situations. So, if you experience signs of infection like coughs, fever, chills and sore throat you must contact your doctor immediately. The appearance of blisters, sores or shedding in the skin is also an area of great concern. Lastly, if you experience extreme fatigue and loss of appetite along with pain in the upper right of your stomach, you must also call your doctor. If there is unusual bleeding or slight yellowness to your skin, you must also take note of it. Such side effects can be manifestations of your body’s resistance to the drug. If this happens, you and your doctor may need to reevaluate your treatment.

Efavirenz has the following structural formula:

Chemical structure of efavirenz

• Molecular formula of efavirenz is C14H9ClF3NO2
• Chemical IUPAC Name is 8-chloro-5-(2-cyclopropylethynyl)-5-(trifluoromethyl)-4-oxa-2- azabicyclo[4.4.0]deca-7,9,11-trien-3-one
• Molecular weight is 315.675 g/mol
Efavirenz available : 50mg capsules, 100mg capsules, 200mg capsules, 600mg tablets

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