Selective intracellular activation of a novel prodrug of the human immunodeficiency virus reverse transcriptase inhibitor tenofovir leads to preferential distribution and accumulation in lymphatic tissue.

Gilead Sciences, Inc., 333 Lakeside Dr., Foster City, CA 94404, USA.
Antimicrobial Agents and Chemotherapy (Impact Factor: 4.45). 06/2005; 49(5):1898-906. DOI: 10.1128/AAC.49.5.1898-1906.2005
Source: PubMed

ABSTRACT An isopropylalaninyl monoamidate phenyl monoester prodrug of tenofovir (GS 7340) was prepared, and its in vitro antiviral activity, metabolism, and pharmacokinetics in dogs were determined. The 50% effective concentration (EC(50)) of GS 7340 against human immunodeficiency virus type 1 in MT-2 cells was 0.005 microM compared to an EC(50) of 5 microM for the parent drug, tenofovir. The (L)-alaninyl analog (GS 7340) was >1,000-fold more active than the (D)-alaninyl analog. GS 7340 has a half-life of 90 min in human plasma at 37 degrees C and a half-life of 28.3 min in an MT-2 cell extract at 37 degrees C. The antiviral activity (>10 x the EC(50)) and the metabolic stability in MT-2 cell extracts (>35 x) and plasma (>2.5 x) were also sensitive to the stereochemistry at the phosphorus. After a single oral dose of GS 7340 (10 mg-eq/kg tenofovir) to male beagle dogs, the plasma bioavailability of tenofovir compared to an intravenous dose of tenofovir was 17%. The total intracellular concentration of all tenofovir species in isolated peripheral blood mononuclear cells at 24 h was 63 microg-eq/ml compared to 0.2 microg-eq/ml in plasma. A radiolabeled distribution study with dogs resulted in an increased distribution of tenofovir to tissues of lymphatic origin compared to the commercially available prodrug tenofovir DF (Viread).

  • [Show abstract] [Hide abstract]
    ABSTRACT: A rapid and sensitive LC method was developed and validated for the determination of diastereomeric purity of tenofovir alafenamide (GS-7340). Baseline separation with resolution > 2.8 was achieved within 17 min on a CHIRALPAK AD-3 (250 x 4.6 mm; particle size 3 mu m) column using n-hexane:2-propanol (60:40 v/v) as the mobile phase at a flow rate of 1 mL min(-1). The analytes were detected by UV absorbance at 260 nm. The effects of ethanol, 2-propanol, and temperature on diastereomeric selectivity and resolution of diastereomerism were evaluated. The method was extensively validated and proved to be robust. The recoveries were between 98.17 and 102.84 % with < 1.93 % relative standard deviation. The limit of detection and limit of quantitation for GS-7339 were 0.77 and 2.56 mu g mL(-1) and for GS-7340 were 0.61 and 2.04 mu g mL(-1), respectively. This method was extensively proved to be accurate, stable, rapid, and sensitive for the determination of diastereomeric purity of tenofovir alafenamide (GS-7340) in bulk samples.
    Chromatographia 10/2014; 77(19-20):1399-1403. DOI:10.1007/s10337-014-2745-2 · 1.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Chronic infection with hepatitis B virus (HBV) constitutes a major global public health threat, causing substantial disease burdens such as liver cirrhosis and hepatocellular carcinoma, thus representing high unmet medical needs. Currently available therapies are safe, well tolerated, and highly effective in decreasing viremia and improving measured clinical outcomes with low rates of antiviral resistance. However, long-term management remains a clinical challenge, mainly due to the slow kinetics of HBV surface antigen clearance. In this article, we review emerging antivirals directed at novel targets derived from mechanisms of viral cellular entry, viral replication, viral assembly, and the host immune response, leading to preclinical and clinical trials for possible future therapeutic intervention. The recent therapeutic advances in the development of all categories of HBV inhibitors may pave the way for regimens of finite duration that result in long-lasting control of chronic hepatitis B infection.
    World Journal of Gastroenterology 06/2014; 20(24):7707-7717. DOI:10.3748/wjg.v20.i24.7707 · 2.43 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A substantial portion of metabolism involves transformation of phosphate esters, including pathways leading to nucleotides and oligonucleotides, carbohydrates, isoprenoids and steroids, and phosphorylated proteins. Because the natural substrates bear one or more negative charges, drugs that target these enzymes generally must be charged as well, but small charged molecules can have difficulty traversing the cell membrane by means other than endocytosis. The resulting dichotomy has stimulated a great deal of effort to develop effective prodrugs, compounds that carry little or no charge to enable them to transit biological membranes, but able to release the parent drug once inside the target cell. This chapter presents recent studies on advances in prodrug forms, along with representative examples of their application to marketed and developmental drugs.


Available from