Differential inhibition of 2'-deoxycytidine salvage as a possible mechanism for potentiation of the anti-human immunodeficiency virus activity of 2',3'-dideoxycytidine by dipyridamole.

Dipyridamole, a commonly used coronary vasodilator and antithrombotic drug, was recently shown to potentiate the activity of 3'-azido-3'-deoxythymidine and 2',3'-dideoxycytidine against the human immunodeficiency virus type 1 (HIV-1) in human monocyte-macrophages in vitro. We report in the present paper that in uninfected monocyte-macrophages dipyridamole significantly inhibits cellular salvage of [3H]deoxycytidine, whereas it does not affect the salvage of [3H]dideoxycytidine. Similar differential inhibition by dipyridamole of the salvage of thymidine, as opposed to 3'-azido-3'-deoxythymidine, was reported previously (G. V. Betageri, J. Szebeni, K. Hung, S. S. Patel, L. M. Wahl, M. Corcoran, and J. N. Weinstein, Biochem. Pharmacol. 40:867-870, 1990). Taken together, these observations suggest that inhibition of the salvage of competing physiological nucleosides may explain or contribute to the potentiating effect of dipyridamole on these antiviral dideoxynucleoside drugs.