Linaclotide is a: (A) Chloride channel activator, (B) CFTR blocker, (C) Somatostatin antagonist, (D) Guanylate cyclase agonist
Answer is D. Linaclotide is a Guanylate cyclase - C agonist that increases levels of cGMP and stimulates secretion of chloride & bicarbonate ions into the intestinal lumen. It is used in treatment of IBS with constipation.