Retroviral meds and treatments

The life cycle of HIV can be as short as about 1.5 days from viral entry into a cell, through replication, assembly, and release of additional viruses, to infection of other cells.[10] HIV lacks proofreading enzymes to correct errors made when it converts its RNA into DNA via reverse transcription. Its short life-cycle and high error rate cause the virus to mutate very rapidly, resulting in a high genetic variability of HIV. Most of the mutations either are inferior to the parent virus (often lacking the ability to reproduce at all) or convey no advantage, but some of them have a natural selection superiority to their parent and can enable them to slip past defenses such as the human immune system and antiretroviral drugs. The more active copies of the virus the greater the possibility that one resistant to antiretroviral drugs will be made.

When antiretroviral drugs are used improperly, these multi-drug resistant strains can become the dominant genotypes very rapidly. Improper serial use of the reverse transcriptase inhibitors zidovudine, didanosine, zalcitabine, stavudine, and lamivudine can lead to the development of multi-drug resistant mutations. The mutations can include the V75I, F77L, K103N, F116Y, Q151M, and the M184V mutation. These mutations were observed before protease inhibitors had come into widespread use. The mutants retained sensitivity to the early protease inhibitor saquinavir. These mutants were also sensitive to the rarely used reverse transcriptase inhibitor foscarnet.[11]

Antiretroviral combination therapy defends against resistance by suppressing HIV replication as much as possible.

Combinations of antiretrovirals create multiple obstacles to HIV replication to keep the number of offspring low and reduce the possibility of a superior mutation. If a mutation that conveys resistance to one of the drugs being taken arises, the other drugs continue to suppress reproduction of that mutation. With rare exceptions, no individual antiretroviral drug has been demonstrated to suppress an HIV infection for long; these agents must be taken in combinations in order to have a lasting effect. As a result, the standard of care is to use combinations of antiretroviral drugs. Combinations usually comprise two nucleoside-analogue RTIs and one non-nucleoside-analogue RTI or protease inhibitor.[12] This three drug combination is commonly known as a triple cocktail.[13] Combinations of antiretrovirals are subject to positive and negative synergies, which limits the number of useful combinations.[14]

In recent years, drug companies have worked together to combine these complex regimens into simpler formulas, termed fixed-dose combinations. For instance, two pills containing two or three medications each can be taken twice daily.[citation needed] This greatly increases the ease with which they can be taken, which in turn increases adherence, and thus their effectiveness over the long-term. Lack of adherence is a cause of resistance development in medication-experienced patients. Patients who maintain proper therapy can stay on one regimen without developing resistance.[citation needed] This greatly increases life expectancy and leaves more drugs available to the individual should the need arise.

Fixed-dose combinations[edit]

Fixed dose combinations are multiple antiretroviral drugs combined into a single pill.

Brand Name Drug Names (INN) Date of FDA Approval Company
Combivir zidovudine + lamivudine September 26, 1997 GlaxoSmithKline
Trizivir abacavir + zidovudine + lamivudine November 15, 2000 GlaxoSmithKline
Kaletra lopinavir + ritonavir September 15, 2000 Abbott Laboratories
Epzicom (in USA) Kivexa (in Europe) abacavir + lamivudine August 2, 2004 GlaxoSmithKline
Truvada tenofovir/emtricitabine August 2, 2004 Gilead Sciences
Atripla efavirenz + tenofovir/emtricitabine July 12, 2006 Gilead Sciences and Bristol-Myers Squibb
Complera rilpivirine + tenofovir/emtricitabine August 10, 2011 Gilead Sciences and Tibotec (Johnson & Johnson)
Stribild elvitegravir + cobicistat + tenofovir/emtricitabine August 27, 2012 Gilead Sciences

The preferred initial regimens in the United States, as of August 2012, are:[15]


About cttbbelliott

I am a married 60 year old woman with four adult children and nearly 12 grandchildren who all live in the southwest U.S. I have lived with the chronic illnesses of CSF and Fibromyalgia for nine years. I am not able to work for a living. I live on the prairie and love God. My Christianity is most important in my life.
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One Response to Retroviral meds and treatments

  1. tlohuis says:
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