Dolutegravir in Initial Therapy: Two Phase 3 Studies

Publish Date: 
Friday, October 5, 2012

Dolutegravir (formerly known as S/GSK 572) is an investigational integrase inhibitor that is in the late stages of development. It is administered once daily and does not require pharmacokinetic boosting. Two recently presented Phase 3 studies evaluated dolutegravir in combination with nucleoside/nucleotide analogues in treatment-naive subjects.

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.

Pitavastatin and Darunavir/Ritonavir

Publish Date: 
Friday, October 5, 2012
Treatment of dyslipidemia is often complicated by drug interactions between statins and antiretrovirals. Pitavastatin is one of the newer statins approved and is one of the few that is not metabolized primarily by the CYP450 3A4 pathway. It is predominantly metabolized via glucuronidation and so, theoretically, is less likely to interact with NNRTIs or PIs.

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.

Cobicistat as a PK Booster of Atazanavir

Publish Date: 
Friday, October 5, 2012

Cobicistat is a derivative of ritonavir and a potent inhibitor of CYP3A. As does ritonavir, it "boosts" blood levels of other substrates of this enzyme but, unlike ritonavir, it has no activity against HIV. It has been developed as a pharmacokinetic enhancer of the integrase inhibitor elvitegravir and of some PIs.

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.

More on Protease Inhibitors and Corticosteroids

Publish Date: 
Friday, May 18, 2012

It has been demonstrated previously that ritonavir significantly increases serum levels of inhaled and intranasal fluticasone and that coadministration with fluticasone should be avoided. Few studies have examined interactions between PIs and other corticosteroids. At the 19th Conference on Retroviruses and Opportunistic Infections, researchers presented results from a randomized controlled PK study of interactions of both darunavir/ritonavir and ritonavir (alone) with inhaled beclomethasone.[1] 

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