Abacavir

IC50 Value: 0.26 microM for HIV-1[1] Abacavir,(-)-(1S,4R)-4-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]-2-cyclopentene-1-methanol, is a novel purine carbocyclic nucleoside analogue that has been approved by the FDA for the treatment of HIV (as Ziagen trade mark [abacavir sulfate]) [2]. in vitro: In erythrocytes, abacavir influx was rapid, nonsaturable (rate constant=200 pmol/s/mM/microl cell water), and unaffected by inhibitors of nucleoside or nucleobase transport[2]. in vivo: pharmacokinetic, distribution, and toxicological profiles of 1592U89 were distinct from and improved over those of CBV, probably because CBV itself was not appreciably formed from 1592U89 in cells or animals (<2%). The 5'-triphosphate of CBV was a potent, selective inhibitor of HIV-1 RT, with Ki values for DNA polymerases (alpha, beta, gamma, and epsilon which were 90-, 2,900-, 1,200-, and 1,900-fold greater, respectively, than for RT (Ki, 21 nM). 1592U89 was relatively nontoxic to human bone marrow progenitors erythroid burst-forming unit and granulocyte-macrophage CFU (IC50s, 110 microM) and human leukemic and liver tumor cell lines[1]. Clinical trial: Estimate The Effect Of Lersivirine On The Pharmacokinetics Of Abacavir + Lamivudine In Healthy Subjects. Phage1

Enantioselective and Regiodivergent Addition of Purines to Terminal Allenes: Synthesis of Abacavir.[Pubmed:28079946]

Angew Chem Int Ed Engl. 2017 Feb 1;56(6):1520-1524.

The rhodium-catalyzed atom-economic asymmetric N-selective intermolecular addition of purine derivatives to terminal allenes is reported. Branched allylic purines were obtained in high yields, regioselectivity and outstanding enantioselectivity utilizing a Rh/Josiphos catalyst. Conversely, linear selective allylation of purines could be realized in good to excellent regio- and E/Z-selectivity with a Pd/dppf catalyst system. Furthermore, the new methodology was applied to a straightforward asymmetric synthesis of carbocyclic nucleoside Abacavir.

[Biliary and kidney lithiasis during treatment with daclatasvir/sofosbuvir/ribavirin and atazanavir/ritonavir + abacavir/lamivudine in an HIV/HCV genotype 4-infected patient: a case report.][Pubmed:28287204]

Recenti Prog Med. 2017 Feb;108(2):98-100.

New Direct-acting Antiviral Agents (DAA)-based anti-HCV therapies currently provide extraordinary opportunities to cure patients. Drug-drug interactions are however a real challenge during treatment. In particular, in HIV-infected patients in cART, DAA choice is limited by such interactions, which can result both in reduced efficacy and toxicity. We report the case of a HIV-infected patient on cART with atazanavir/ritonavir/Abacavir/lamivudine, who presented kidney and biliary lithiasis, the latter treated with endoscopic retrograde cholangiopancreatography and endoscopic biliary sphincterotomy, after beginning anti-HCV treatment with daclatasvir/sofosbuvir/ribavirin. Hyperbilirubinemia with or without jaundice is a well known side effect of atazanavir, because of its inhibition of uridine diphosphate-glucuronosyl transferase. We speculate that in this case hyperbilirubinemia worsening was due to atazanavir/ribavirin co-administration. However, pharmacokinetic data are lacking about atazanavir/daclatasvir concomitant administration in real life setting.

Correction: Abacavir/Lamivudine plus Rilpivirine Is an Effective and Safe Strategy for HIV-1 Suppressed Patients: 48 Week Results of the SIMRIKI Retrospective Study.[Pubmed:28182783]

PLoS One. 2017 Feb 9;12(2):e0172184.

[This corrects the article DOI: 10.1371/journal.pone.0164455.].

Abacavir induces platelet-endothelium interactions by interfering with purinergic signalling: A step from inflammation to thrombosis.[Pubmed:28263802]

Antiviral Res. 2017 May;141:179-185.

The controversy connecting Abacavir (ABC) with cardiovascular disease has been fuelled by the lack of a credible mechanism of action. ABC shares structural similarities with endogenous purines, signalling molecules capable of triggering prothrombotic/proinflammatory programmes. Platelets are leading actors in the process of thrombosis. Our study addresses the effects of ABC on interactions between platelets and other vascular cells, while exploring the adhesion molecules implicated and the potential interference with the purinergic signalling pathway. The effects of ABC on platelet aggregation and platelet-endothelium interactions were evaluated, respectively, with an aggregometer and a flow chamber system that reproduced conditions in vivo. The role of adhesion molecules and purinergic receptors in endothelial and platelet populations was assessed by selective pre-incubation with specific antagonists and antibodies. ABC and carbovir triphosphate (CBT) levels were evaluated by HPLC. The results showed that ABC promoted the adherence of platelets to endothelial cells, a crucial step for the formation of thrombi. This was not a consequence of a direct effect of ABC on platelets, but resulted from activation of the endothelium via purinergic ATP-P2X7 receptors, which subsequently triggered an interplay between P-selectin and ICAM-1 on endothelial cells with constitutively expressed GPIIb/IIIa and GPIbalpha on platelets. ABC did not induce platelet activation (P-selectin expression or Ca(2+) mobilization) or aggregation, even at high concentrations. CBT levels in endothelial cells were lower than those required to induce platelet-endothelium interactions. Thus, ABC interference with endothelial purinergic signalling leads to platelet recruitment. This highlights the endothelium as the main cell target of ABC in this interaction, which is in line with previous experimental evidence that ABC induces manifestations of vascular inflammation.