Sprague-Dawley rats were given a single IM injection of 75 mg/kg 3TC equivalents as NM23TC. (A) Prodrug concentrations in whole blood were measured at days 1,7,14, 21, and 28. (B) Prodrug levels in liver were measured at days 1 and 28. Prodrug (red) and 3TC-TP (magenta) levels in (C) lymph node, and (D) spleen were determined at days 1 and 28.