Abacavir increases platelet reactivity via competitive inhibition of soluble guanylyl cyclase

Division of Experimental Medicine, Department of Medicine bVeterans Affairs Medical Center, University of California San Francisco, San Francisco, California 94143-1234 , USA.
AIDS (London, England) (Impact Factor: 5.55). 09/2011; 25(18):2243-8. DOI: 10.1097/QAD.0b013e32834d3cc3
Source: PubMed


To provide a molecular mechanism that explains the association of the antiretroviral guanosine analogue, abacavir, with an increased risk of myocardial infarction.
Drug effects were studied with biochemical and cellular assays.
Human platelets were incubated with nucleoside analogue drugs ex vivo. Platelet activation stimulated by ADP was studied by measuring surface P-selectin with flow cytometry. Inhibition of purified soluble guanylyl cyclase was quantified using an ELISA to measure cGMP production.
Pre-incubation of platelets in abacavir significantly increased activation in response to ADP in a time and dose-dependent manner. The active anabolite of abacavir, carbovir triphosphate, competitively inhibited soluble guanylyl cyclase activity with a K(i) of 55 μmol/l.
Abacavir competitively inhibits guanylyl cyclase, leading to platelet hyperreactivity. This may explain the observed increased risk of myocardial infarction in HIV patients taking abacavir.

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    • "It is also noteworthy that abacavir, an NRTI, has been demonstrated previously to enhance activation of platelets, thus sensitizing these cells to additional stimuli [18], [19], and was shown to modestly activate platelets directly, as measured by P-selectin surface expression [18]. Interestingly, we did not observe that platelets exposed to abacavir and lamivudine alone induce direct activation, as measured by the release of sCD40L (Figure 2). "
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