Discovery of Orally Available 8-Aza-5-thiaProstaglandin E1 Analogs as Highly Selective EP4 Agonists

Analogs 8-aza-16-aryl prostaglandin E1 (PGE1) and 8-aza-5-thia-16-arylPGE1 were synthesized and evaluated with respect to their subtype receptor affinity and EP4 agonist activity for the purposes of identifying subtype-selective EP4 agonists that demonstrate oral efficacy. Using an inhibition assay of lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF)-α production in rats, representative compounds were evaluated for their pharmacokinetic profiles and in vivo efficacy. Structure–activity relationships (SARs) were characterized and presented. Of the compounds tested, several demonstrated better oral exposure and/or in vivo efficacy compared with the previously reported analog 2a.