The present application describes compounds according to both Formulas I and II, pharmaceutical compositions comprising at least one compound according to either Formula I or II and optionally one or more additional therapeutic agents, and methods of treatment using the compounds according to Formulas I and II both alone and in combination with one or more additional therapeutic agents. The compounds have the following general formulas: ##STR00001## including all prodrugs, solvates, pharmaceutically acceptable salts and stereoisomers, wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are described herein.