Tenofovir

Tenofovir disoproxil fumarate (TDF or PMPA^[1]), marketed by Gilead Sciences under the trade name Viread®, belongs to a class of antiretroviral drugs known as nucleotide analogue reverse transcriptase inhibitors (nRTIs), which block reverse transcriptase, an enzyme crucial to viral production in HIV-infected people.

Tenofovir is also available in a fixed-dose combination with emtricitabine in a product with the brand name Truvada® for once-a-day dosing. (Emtricitabine is marketed as a single-compound product called Emtriva®, also by Gilead.) Atripla®, a fixed-dose triple combination of tenofovir, emtricitabine and efavirenz, was approved by the FDA on 12 July 2006 and is now available, providing a single daily dose for the treatment of HIV.

Tenofovir is indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection in adults. This indication is based on analyses of plasma HIV-1 RNA levels and CD4 cell counts in controlled studies of tenofovir in treatment-naïve and treatment-experienced adults. There are no study results demonstrating the effect of tenofovir on the clinical progression of HIV.

Tenofovir can cause acute renal failure, fanconi syndrome, proteinuria, tubular necrosis. These side effects are due to accumulation of drug in proximal tubule. Tenofovir can interact with didanosine by increasing didanosine's concentration. It also decreases the concentration of Atazanavir's.

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History

Tenofovir was discovered through a collaborative research effort between Antonín Holý at the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic (IOCB) in Prague, and Erik DeClercq, Rega Institute for Medical Research, Catholic University of Leuven, Belgium.

Tenofovir was approved by the U.S. Food and Drug Administration (FDA) on October 26, 2001. It is currently in late-stage clinical trials for the treatment of hepatitis B.

Adverse Effects

The most common side effects associated with tenofovir include nausea, vomiting, diarrhea, and asthenia. Less frequent side effects include hepatotoxicity, abdominal pain, and flatulence.^[2] Tenofovir has also been implicated in causing renal toxicity, particularly at elevated concentrations.^[3]

HIV risk reduction

A 2006 trial by Family Health International gave either Viread or a placebo to 936 high-risk women in Cameroon, Ghana and Nigeria. While the results show signs that the Viread group contracted HIV at a reduced rate, the researchers cautioned against drawing conclusions from the study because the sample size was so small.^{[4] [5]}

References

1. ^ Emau P, Jiang Y, Agy MB, et al. (2006). "Post-exposure prophylaxis for SIV revisited: Animal model for HIV infection". AIDS Res Ther 3: 29. doi:10.1186/1742-6405-3-29.
2. ^ (2005) USPDI. Thompson, 2741-2. 
3. ^ Viread Prescribing Guidelines. FDA (March 2006). Retrieved on 2007-02-12.
4. ^ Tenofovir Use Safe for Uninfected, West African Women at Risk of HIV Infection. Family Health International (2006-08-17). Retrieved on 2007-06-01.
5. ^ Additional Studies Needed to Assess Effectiveness of Tenofovir for Prevention. Family Health International. Retrieved on 2007-06-01.