Pimilprost (SM-10902) and its free acid, SM-10906 are new stable 3-oxa-methano prostaglandin (PG) I1 analogs, SM-10902 is a prodrug of SM-10906. SM-10906, but not SM-10902 was demonstrated to be an agonist for IP receptors. SM-10906 was shown to exert its anti-platelet and vasodilatory activities through the increase of the cAMP level. Pimilprost was being developed by Dainippon Sumitomo Pharma (formerly Sumitomo Pharmaceuticals) in Japan for the treatment of skin ulcers. In Japan, an NDA was filed for pimilprost and was awaiting registration. However, development appears to have been discontinued.

Naluzotan (PRX-00023), a small molecule, non-azapirone, dual serotonin (5-HT)1A receptor agonist and sigma-1 receptor antagonist, is under development with Proximagen for the treatment of epilepsy. In previous clinical trials, the compound was shown to be safe and well-tolerated in over 400 patients. Epilepsy patients with localisation-related epilepsy have reduced 5-HT1a receptor binding as indicated by positron emission tomography (PET scan). It is thought that by increasing neurotransmitter activity at 5-HT1a receptor sites, seizure incidence and severity may be decreased.

Naronapride (ATI-7505), an orally administered, cisapride analogue and serotonin4 (5HT4) receptor agonist, is being developed by Renexxion for the treatment of multiple gastrointestinal disorders. Sinovant is initially developing naronapride for the treatment of irritable bowel syndrome – constipation (IBS-C), a disease that affects millions of Chinese patients and for which few effective treatment options are available. Naronapride has been evaluated in over 900 subjects in multiple randomized controlled clinical studies and has demonstrated promising results in patients with gastroesophageal reflux disease (GERD), erosive esophagitis (EE), and chronic idiopathic constipation (CIC). Naronapride’s low systemic absorption and high specificity for 5HT4 and D2 receptors is thought to improve its safety and tolerability profile relative to other members of the class.