<prompt> Despite their sho half-lives 2 hours, Proton pump Inhibitors PPIs cause a prolonged suppression of acid secretion up to 48 hours because:They are prodrugs and undergo activation graduallyThey exit from the plasma and enter acid secretory canaliculi and stay there, blocking the secretion of acid for a long timeThey irreversibly inhibit the proton pump molecule and hence, acid secretion requires synthesis of new proton pumpsThey are available as enteric coated capsules, from which drug is gradually released  <response>: Ans. c. They irreversibly inhibit the proton pump molecule and hence, acid secretion requires synthesis of new proton pumps Inhibition of acid secretion is also more prolonged because of the irreversible inhibition of the enzyme caused by the covalent bond to the proton pump. 