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Drug review: Descovy

Thursday, May 18, 2017  
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Student Submission: Drug review: Descovy

Christine A. Dimaculangan is a 6th year pharmacy student at the Philadelphia College of Pharmacy at the University of the Sciences. 

Diane E. Hadley is a faculty member at the Philadelphia College of Pharmacy at University of the Sciences. She is an ambulatory care clinical pharmacy specialist. 

 

Descovy® is an anti-retroviral medication combination of emtricitabine (FTC or F) and tenofovir alafenamide (TAF).1 Descovy®’s mechanism of action is the inhibition of the viral replication of HIV.1 It is indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection and is approved for use in patients 12 years and older.1 It was approved on April 4th, 2016.1

In a trial by Mills A, et al., they evaluated the efficacy of a regimen containing D/C/F/TAF vs. DRV + COBI + F/TDF* (both in tablet form) in HIV-1 infected ART-naïve adult participants.2  The authors of this study also evaluated safety and tolerability outcomes using standard descriptive methods.2 Patients who received at least one dose of the study drug were eligible.2  Efficacy was determined by the achievement of HIV-1 RNA <50 copies/mL at week 24 of treatment.2  Even though we are only interested in the “F/TAF” part of the regimen, it is standard for patients to be on multiple medications.2 This trial was a randomized, double-blinded, multi-center, active-controlled study that was conducted from April 2012 to February 2014.2 The trial included patients who were HIV-1 positive, treatment-naïve, older than 18 years, had a CD4+ cell count of >50 cells/μL, and a plasma HIV-1 RNA count of 5000 copies/mL.2  The TAF-treatment group received D/C/F/TAF STR, 2 matched DRV 400 mg placebos, COBI placebo, and F/TDF placebo and the TDF group received D/C/F/TAF placebo, 2 DRV 400 mg tablets, COBI tablet, and F/TDF tablet.2 Baseline characteristics were similar between both treatment groups, and a majority of patients in this study were male approximately 33 years of age.2

 

At week 24, 74.8% of patients in the TAF treatment group vs. 74.0% in the TDF group were virally suppressed (defined as having an HIV-1 RNA <50 copies/mL).2 The weighted difference in response rate was 3.3% (95% CI: -11.4 to 18.1), meeting the margin of non-inferiority.2  Neither treatment groups experienced severe adverse events or mortality.2 The authors concluded that TAF was non-inferior to TDF in terms of efficacy, and showed that there was an improvement in bone and renal safety parameters with TAF when compared to TDF.2 As of now, Descovy® has no specific place in the 2016 Guidelines for the Use of Antiretroviral agents in HIV-1-Infected Adults and Adolescents, but its two individual components are mentioned in the guidelines.3

*Full name of abbreviated drug names:

  • D/C/F/TAF: Darunavir, cobicistat, emtricitabine, tenofovir alafenamide2
  • DRV+ COBI + F/TDF: Darunavir, cobicistat, emtricitabine, tenofovir disoproxil fumarate2

Dosage, Costs, and Pharmacokinetics

            Each tablet contains 200 mg FTC and 25 mg of TAF.1 This medication is to be dispensed and stored ONLY in its original container.1 A 30-day supply of this medication costs approximately $1,759.73.4 Since this is a combination medication, pharmacokinetics differ depending on the respective drugs. FTC is rapidly absorbed, 93% bioavailable and its half-life (with normal renal function) is 11 hours (as a single dose).4 FTC is excreted 86% primarily as unchanged drug in the urine with the remainder excreted in the feces.4 TAF is rapidly absorbed and its concentration is increased by 75% when administered with a high fat meal.1 It is highly protein bound (80%) and is metabolized via cathepsin A in peripheral blood mononuclear cells and CYP3A4 in the liver.1 TAF is excreted primarily via feces (31.7%) and is 54% dialyzable.4 It has a half-life of 0.5 hours.4

Drug interactions & side effects:

            Descovy® is a substrate of PgP, BCRP, as well as OATP1B1 and OATP1B3.4 Drugs that alter these transporters may change its absorption.4 Specific drug interactions should be reviewed respectively in detail. It is important to monitor for bone mineral density, changes in appearance (as it could affect the body fat of the patient), changes in response of immune system, or any emerging kidney problems or worsening of kidney problems.1 Descovy®’s Black Box Warning includes lactic acidosis, severe hepatomegaly with steatosis, and post-acute exacerbation of hepatitis B.1,4

Drug at a glance1:

  • Indications: In combination with other antiretroviral agents for the treatment of HIV-1 infection in patients 12 years and older
  • Contraindications: None listed per the package insert

In summary5:

TAF and TDF are both pro-drugs and require conversion to the active drug, tenofovir diphosphate. While these are both prodrugs, TDF is delivered in the blood and into the cells in its converted form. TAF, is delivered as TAF to the cells and then converted, so there is less of the active drug circulating in the blood which leads to a decrease in adverse events (such as renal and bone toxicities). As per the cost, Descovy®, in a bottle of 30, is approximately $1881.14 and Truvada® (TDF and emtricitabine) in a bottle of 30, is the same price.  Based on the aforementioned information, TAF would best be used for patients who have renal disorders, have bone abnormalities, or who have experienced many different adverse effects with the use of TDF. 

 

References:

1.      Prescribing information. Descovy®. 4/2016 ed. Gilead Sciences.  Foster City, CA: 2016.

2.      Mills A, Crofoot GJ, McDonald C, Shalit P, Flamm JA, Gathe J, Scribner A, Shamblaw D, Saag M, Cao H, Martin H, Das M, Thomas A, Liu HC, Yan M, Callebaut C, Custodio J, Cheng A, and McCallister S. Tenfovir alafenamide versus tenofovir disoproxil fumarate in the first protease inhibitor-based single-tablet regimen for initial HIV-1 therapy: a randomized phase 2 study. J Acquir Immune Defic Syndr 2015;69:439-445.

3.      Panel on Antiretroviral Guidelines for Adults and Adolescents. Guidelines for the use of antiretroviral agents in HIV-1 infected adults and adolescents. Department of Health and Human Services. Available at http://aidsinfo.nih.gov/contentfiles/lvguidelines/AdultandAdolescentGL.pdf.

4.      Micromedex® 2.0 [electronic version]. Redbook onlineTM. Truven Health Analytics, Greenwood Village, CO, USA. Available at: http://www-micromedexsolutions-com.db.usciences.edu/ (cited: November 16, 2016).

Zolopa A, Ortiz R, Sax P, et al. Comparative study of tenofovir alafenamide vs tenofovir disoproxil fumarate, each with elvitegravir, cobicistat, and emtricitabine, for HIV treatment. In: Program and abstracts of the 20th Conference on Retroviruses and Opportunistic Infections; March 3-6, 2013; Atlanta. Abstract 99LB.



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