Comparison of 2 Tenofovir Prodrugs: TAF (GS 7340) and TDF

Publish Date: 
Wednesday, May 1, 2013

Tenofovir alafenamide fumarate (TAF) is an investigational prodrug of tenofovir. You will recall that the current tenofovir product, tenofovir disoproxil fumarate (TDF), also is a prodrug; so why are we interested in a new prodrug? This largely has to do with efforts to decrease the toxicity associated with tenofovir.

Interactions with Hepatitis C Protease Inhibitors

Publish Date: 
Wednesday, May 1, 2013

Rilpivirine and Boceprevir

Boceprevir (BOC) is a hepatitis C virus (HCV) NS3/4A protease inhibitor used in combination with pegylated interferon + ribavirin for the treatment of HCV. As BOC is an inhibitor of hepatic cytochrome (CYP) 3A4, and many protease inhibitors and NNRTIs affect or are affected by this hepatic isoenzyme, interactions are expected.

More on Interactions between Darunavir and Pravastatin: To Use or Not to Use?

Publish Date: 
Friday, May 18, 2012

Recommendations for coadministration of pravastatin with darunavir have been based on a small PK study that showed substantial intersubject variability in the impact of interactions between the two drugs.[1] In that study, concurrent administration of pravastatin (40 mg, single dose) with darunavir/ritonavir 600 mg/100 mg BID resulted in an overall geometric mean increase in pravastatin AUC of 81% and Cmax of 63%, compared with levels when pravastatin was taken alone.

Darunavir + Raltegravir without NRTIs, revisited

Publish Date: 
Monday, January 2, 2012

In early 2011, a single-arm study of the NRTI-sparing regimen of darunavir/ritonavir (800/100 mg QD) plus raltegravir (400 mg BID) reported worrisome rates of virologic failure, particularly among subjects with baseline HIV RNA levels of >100,000 copies/mL.(1) At ICAAC, researchers involved in a second study to evaluate this combination presented their 24-week results.

ARV Interactions with HCV Serine Protease Inhibitors

Publish Date: 
Tuesday, April 17, 2012

Boceprevir and telaprevir, the hepatitis C virus (HCV) serine protease inhibitors, are likely to play important roles in the treatment of individuals with HIV/HCV coinfection, as well as in persons with HCV monoinfection. However, both boceprevir and telaprevir are inhibitors and substrates of cytochrome P450 3A4 (CYP3A4); thus, interactions with antiretroviral (ARV) medications used for treatment of HIV are expected, particularly HIV protease inhibitors (PIs) and nonnucleoside reverse transcriptase inhibitors (NNRTIs). Few studies have examined drug-drug interactions between HCV protease inhibitors and ARVs, but the available data do make it clear that the HCV PIs have significant interactions with certain ARVs. Interactions, especially those involving HIV PIs and NNRTIs, may substantially affect the efficacy or toxicity of either HCV therapy or HIV therapy (though in many cases the clinical impact of these interactions has not been studied). The table below presents a summary of known interactions between ARVs and HCV PIs, along with recommendations for coadministration.

Switching from Efavirenz to Rilpivirine

Publish Date: 
Monday, January 2, 2012

It has been reported previously that efavirenz reduces serum levels of rilpivirine and that this effect may be prolonged, even after discontinuation of efavirenz (see Sustained Effect of Efavirenz on Rilpivirine Serum Concentrations). A small, nonrandomized study was designed to answer the question of whether it is possible to switch directly from efavirenz to rilpivirine without loss of virologic control.

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