Active Ingredients

Efavirenz – Effect, Application & Risks


Efavirenz is a non-nucleoside reverse transcriptase inhibitor. The drug is used to treat HIV infections .

What is efavirenz?

The active ingredient efavirenz (EFV) belongs to the group of non-nucleoside reverse transcriptase inhibitors (NNRTI). The drug is used as a pure enantiomer and is used to treat HIV infections such as AIDS . It is part of an antiretroviral combination treatment.

Efavirenz was approved as a medicinal product in Europe by the EMEA (European Medicines Agency) in 1999. However, because resistance to the drug quickly develops in monotherapy, the non-nucleoside reverse transcriptase inhibitor must always be taken with another antiretroviral drug that the patient has never received before. Efavirenz was already on the market in North America before it was approved in Europe.

Efavirenz is available as a monopreparation under the trade name Sustiva® in Germany. There is also a combination drug called Atripla®.

Pharmacological action

Viruses are not able to multiply independently. For this purpose they need the replication apparatus of the cells they have infested. In order to achieve this, the viruses insert the genetic material of the cells into their own genetic material. The cells receive blueprints that they use to produce the viruses. This process is more difficult with HI viruses, since their genome is shaped differently than that of mammals and humans.

In order for the genetic material of the HI virus to be able to get into human cells, it has to be “rewritten”. The enzyme reverse transcriptase is responsible for this change . In this way, the HI virus can rearrange its genome in such a way that it can easily be introduced into the human genome.

Because efavirenz belongs to the group of reverse transcriptase inhibitors, it has the ability to block the reverse transcriptase active site. As a result, the enzyme is no longer able to rewrite the genome of the virus. The information is classified as foreign by the body cells and is therefore no longer reproduced. This counteracts the production of new HI viruses.

This process reduces the viral load, thereby delaying the onset of AIDS. It also reduces the symptoms of HIV infection, which in turn improves the patient’s quality of life.

Efavirenz is 99 percent bound to plasma proteins in the blood . Its concentration in cerebrospinal fluid is three times higher than in blood plasma . The half-life of the active ingredient is around 50 hours. One-third of efavirenz is excreted in the form of metabolites in the urine . The rest of the substance leaves the organism via the stool without any changes.

Medical Application & Use

Efavirenz is only used for HIV infections, in which the human body has an immune deficiency . The remedy can be used in adult and adolescent patients as well as in children from the age of three.

As a drug to inhibit viruses, efavirenz acts directly against the HI viruses. However, it is also possible to counteract or slow down the outbreak of AIDS.

Eating high-fat foods may affect the absorption of efavirenz. It increases by about 50 percent. The drug is usually taken in the evening on an empty stomach before bedtime. Since the half-life of efavirenz is long, a single dose of the drug per day is sufficient. Efavirenz can be taken as a solution or in the form of film-coated tablets.

Risks & side effects

There is a risk of side effects associated with the use of efavirenz, primarily affecting the central nervous system (CNS). The affected patients often suffer from tiredness , drowsiness , sleep problems , nightmares and dizziness . Up to 50 percent of all patients are affected by these undesirable side effects, especially in the initial phase of efavirenz treatment.

Other side effects may include difficulty concentrating , anxiety , depression , headache , abdominal pain , diarrhea , nausea , skin rashes, and itching . In most cases, these side effects improve after one to four weeks. However, symptoms persist in 10 to 20 percent of all those affected, so it is then advisable to switch to another preparation.

Sometimes there are also other side effects such as acute inflammation of the liver ( hepatitis ), acute inflammation of the pancreas ( pancreatitis ), mood swings , euphoria , aggressiveness , paranoia, delusions , restlessness , memory problems, movement disorders , balance disorders , cramps , visual disturbances , confusion and suicidal thoughts which can lead to a suicide attempt.

If skin blisters , mucous membrane changes, skin peeling and fever form on the skin during treatment , you should urgently consult your doctor and possibly discontinue the therapy.

Because side effects are often associated with ingestion, it is recommended that efavirenz be administered on an empty stomach. In some cases, the drug causes disturbances in the distribution of body fat. The fat on the body and face decreases while it increases in the abdomen.

There are also some contraindications to taking efavirenz. It should not be used if the patient is hypersensitive to the active ingredient or has severe liver damage . Strict medical supervision is necessary in the case of renal dysfunction , liver disease , epilepsy , psychiatric disorders in advance or resistance to other HIV drugs.

Efavirenz should only be taken during pregnancy if there are no other treatment options. Animal testing revealed harmful effects on the child from the drug.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.