The present invention relates to CCR5 receptor antagonists of formulae (1a) or (1b): ##STR00001## enantiomers, diastereomers, salts and solvates thereof wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, and R.sup.7 are as defined herein. The invention further includes a method of CCR5-mediated disorders employing such compounds.