Birch, Stewart, Kolasch & Birch, LLP
Acyclic nucleoside derivatives
 Compounds of the Formula I ##STR1## PA1 where one of R.sub.1 and R.sub.2 is --C(O)CH(CH(CH.sub.3).sub.2)NH.sub.2 or --C(O)CH(CH(CH.sub.3)CH.sub.2 CH.sub.3)NH.sub.2 ; PA1 the other of R.sub.1 and R.sub.2 is --C(.dbd.O)C.sub.3 -C.sub.21 saturated or monounsaturated, optionally substituted alkyl; and PA1 R.sub.3 is OH or H; and pharmaceutically acceptable salts thereof have utility as enhanced bioavailability antivirals against herpes and retroviral infections. 
Medivir AB
A A Y C C A
A61P A61P Y02P C07D C07D A61P
inventional inventional additional inventional inventional inventional
Bjorn Marita Nils-Gunnar Per Xiao-Xiong
Lindborg Hogberg Johansson Engelhardt Zhou