A cell-based, high-throughput screen was performed for 120,000 drug-like, synthetic small molecules. Active compounds were characterized for mechanism of action and one lead compound was tested in a loperamide-induced constipation model in mice.
Several classes of novel CFTR activators were identified, one of which, the phenylquinoxalinone CFTRact-J027, fully activated CFTR chloride conductance with an half-maximal effective concentration (EC50) of approximately 200 nmol/L, without causing an increase of cytoplasmic cyclic adenosine monophosphate. Orally administered CFTRact-J027 normalized stool output and water content in a loperamide-induced mouse model of constipation with a 50% effective dose of approximately 0.5 mg/kg; CFTRact-J027 was without effect in cystic fibrosis mice lacking functional CFTR. Short-circuit current, fluid secretion, and motility measurements in mouse intestine indicated a prosecretory action of CFTRact-J027 without direct stimulation of intestinal motility. Oral administration of 10 mg/kg CFTRact-J027 showed minimal bioavailability, rapid hepatic metabolism, and blood levels less than 200 nmol/L, and without apparent toxicity after chronic administration.
CFTRact-J027 or alternative small-molecule CFTR-targeted activators may be efficacious for the treatment of constipation.