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