AL 8810 is an 11β-fluoro analog of PGF2α which acts as a potent and selective antagonist at the FP receptor.{7398} (S)-AL 8810 is the C-15 epimer of AL 8810, having the inverse, (S), or ``natural'' configuration at C-15 relative to AL 8810, which is 15-(R). The pharmacology of (S)-AL 8810 has not been published.