The present application describes compounds according to Formula I, pharmaceutical compositions comprising at least one compound according to Formula I and optionally one or more additional therapeutic agents and methods of treatment using the compounds according to Formulas I 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 B, R.sup.1, R.sup.2, R.sup.3 and x are described herein.