Efavirenz
What is efavirenz?
The first HIV drug granted traditional FDA approval based on the exceptional length of the treatment response. Efavirenz is also known as EFV, Sustiva, or DMP 266. This drug is manufactured by DuPont Pharmaceuticals Company.
Efavirenz is a form of antiviral therapy for treating HIV-1. It is a non-nucleoside reverse transcriptase inhibitor (a.k.a. "non-nuke" or NNRTI).
How does efavirenz work?
This antiviral drug exhibits the ability to prohibit HIV from replicating, which is accomplished by preventing the reverse transcriptase enzyme from properly functioning. The purpose of this enzyme is to change the RNA of the virus so that it becomes DNA. Once this occurs, the material which encodes HIV will be inserted into the genetic code of an infected cell.
Who should take efavirenz?
Those for which efavirenz is most beneficial is HIV-infected individuals. Typically this drug is administered when several symptoms of HIV disease are manifested, the T-cell (CD4 cell) count is below 500, and the viral load is over 30,000.
The optimal time at which this drug must be first administered is not clear. This is decided by the individual doctor and patient. Factors included in this decision are: T-cell count, viral load, symptoms, and the patient's attitude towards taking HIV medications.
How effective is efavirenz?
The half-life of this drug is 52 to 76 hours if taken as a single-dose. This declares its effectivity in that this drug need be taken only once a day.
Efavirenz is most commonly used in combination with other antiviral drugs. Clinical studies have shown that when efavirenz is taken once daily in conjunction with zidovudine plus lamivudine or nelfinavir, the T-cell count increased and the HIV RNA plasma level decreased to manageable levels. The induced reduction in viral load can be maintained for 72 weeks, as seen in one clinical trial.
There have been reports of clinically significant drug interactions between efavirenz and indinavir and saquinanivr.
This drug is able to cross the blood-brain barrier and thus displays the ability to enter the central nervous system. This allows its utilization in preventing mental problems such as dementia.
How is efavirenz taken and how much is taken?
Efavirenz is administered orally as a capsule. The dosage for a normal adult is 600 mg once a day at bedtime. Typically the dosage is taken as 3 capsules, each of 200 mg, although a 600 mg pill is being developed.
What are some precautions of efavirenz?
Because efavirenz is metabolized by the liver, there can be adverse interaction between this drug and other drugs which use the liver. For this reason it is imperative that the patients informs their doctor of all the drugs they are taking.
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Efavirenz lowers blood levels of most protease inhibitors. Because of this, dosages of indinavir and amprenavir should be increased. |
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Efavirenz lowers blood levels of methadone and so this will need to be increased as well. |
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Efavirenz and saquinavir should not be taken together. |
What are the side effects of efavirenz?
The most common side effects consist of nausea, dizziness, a rash, headache, insomnia, and diarrhea. These nervous system symptoms and dermatological adverse effects are usually midly severe and generally last only 12 to 21 days.
Nervous system symptoms are reduced by administering efavirenz at bedtime. Dermatological effects are managed by using topical corticosteroids and antihistamines.
As studies in monkeys have displayed that efavirenz is implied in causing birth defects, it is not advisable for pregnant women to take this drug.