Abacavir is a drug that inhibits the proliferation and release of viruses. Specifically, abacavir is used as an antiviral in HIV-infected patients. It is an element in a combination therapy.

What is Abacavir?

Abacavir is a drug that inhibits the proliferation and release of viruses. Specifically, abacavir is used as an antiviral in HIV-infected patients.

GlaxoSmithKline plc. (GSK) as a British pharmaceutical company is the manufacturer of the drug Abacavir. As part of a combination antiretroviral therapy, HIV-1 patients are being treated.

Abacavir belongs to the group of nucleoside reverse transcriptase inhibitors (NRTIs). It is a nucleoside analogue. This is similar to the natural nucleoside. They start in their action on the enzyme reverse transcriptase. This enzyme is part of retroviruses and transcribes the viral RNA genome into DNA.

Abacavir competes with the natural nucleosides. However, it does not have a 3rd hydroxyl group. Thus, no chain extension can take place. Therapy with abacavir should be started only after a genetic test, as a certain gene marker (HLA-BSternchen5701) can cause life-threatening reactions.

Pharmacological action

Abacavir is a nucleoside analog. It lacks the 3rd hydroxyl group. This prevents chain extension during transcription. Transcription is the biological process in which genetic information is transferred from the DNA strands to the RNA.

The base sequences of RNA and DNA must be complementary. Transcription is then catalyzed in the nucleus. Abacavir works against it. It inhibits viral regeneration. Pharmacodynamically, abacavir is first converted into a triphosphate. These are chemically synthesized equivalents of phosphoric acid. Furthermore, the base portion is biochemically rebuilt or degraded by the body's own enzyme systems. The result is a biochemically active metabolite.

This metabolite (carborvir triphosphate) inhibits chain extension and thus blocks transcription. In addition to the manipulation of transcriptase, there is also an end to DNA chain formation. The missing hydroxyl group prevents linking to 2 pages. Treatment with abacavir or a combination of NRTI reduces viral load.

At the same time an increase in the CD4 cell count is caused. According to scientific studies, the use of abacavir slows down the progression of immunodeficiency, reduces AIDS-typical infections and thus significantly prolongs life. According to other study results, however, the benefit loses over time. This is due to the mutability of the H virus.

Medical application & use

Abacavir is a synthetic molecule that builds up inhibitory activities against immune deficiency AIDS in the body. The degradation of abacavir in the body is not by the cytochrome P450 system, but by alcohol dehydrogenase and further by glucuronyl - transferase.

Interactions with other drugs are avoided as far as possible. In vitro, abacavir shows good activity against HIV-1 and its effects can be enhanced by amprenavir, nevirapine and zidovudine. Also combined drugs, such as lamivudine and stavudine, significantly enhance the effect. Only slowly develops the viral resistant to abacavir. It needs a lot of mutations.

In adults who were treated with a combination of abacavir with lamivudine and zidovudine, 70 percent had a viral load at 48 weeks that was undetectable. Also, the CD-4 cell count increased significantly. In children with HIV-1, a comparative study was conducted. These children had unblinded NRTI and the proportion of detectable viral load (less than 400 copies / ml) was significantly higher in combination with abacavir than comparable drugs.

Risks & Side Effects

In known hypersensitivity to abacavir (checked by genetic test) or in severe liver dysfunction the drug should not be taken. Limited use of abacavir is recommended during pregnancy or lactation.

Furthermore, hepatitis, metabolic acidosis or hepatomegaly are against the use of the drug. If the patient is known to have high risk factors for liver disease or if the patient carries a very high viral load, the use of abacavir, especially in combination with lamivudine and zidovudine, is of concern.

Also, moderate liver dysfunction or end-stage renal disease is one of the relative contraindications of abacavir. About 5 percent of patients show hypersensitivity reactions. Symptoms include rash, nausea, vomiting, abdominal pain, cough, elevated liver function, mouth ulcers, headache, and a general malaise. Tags: 

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