Compare and contrast the pharmacology of drugs that alter the pH of gastric
Moderately well answered overall, however many candidates lacked a systematic
approach to their comparison of the pharmacology of drugs that alter the pH of
gastric fluid. Few candidates discussed pharmacokinetics in sufficient detail, with
only a very limited discussion comparing the absorption, metabolism and elimination
of even common drugs. Relevant information such as bioavailability, duration of
effect, and available formulations with dosing was often lacking. Similarly, little
attention was given to important drug interactions. Many candidates included drugs
which are used for gastric problems or mucosal protection, but do not specifically
influence gastric pH e.g. sucrulfate. Some candidates gave unnecessarily detailed
accounts of the physiology of gastric fluid production and the acid-base mechanisms
involved. All candidates provided details of H2 blockers and PPIs, but often did not
list representative examples or compare the effects on basal versus stimulated acid
secretion. Many candidates also discussed antacids, but did not indicate their
mechanisms of action properly and did not outline potential adverse effects. Some
candidates included prostaglandin analogues and anticholinergic drugs for
completeness and were able to indicate their roles in affecting gastric acid secretion.
Syllabus: Q2a 2b,c
Recommended sources: Basic and Clinical Pharmacology, Katzung, Chp 62
It would be important to point out that sucralfate in fact does affect gastric pH, as it is a complex salt of aluminium hydroxide and sulfated sucrose. When it disperses in stomach acid, it releases a surprising amount of aluminium hydroxide, which then goes on to do some good antacid work.
Available classes are:
|Mechanism of action||
Aihara, Takeshi, et al. "Pharmacological control of gastric acid secretion for the treatment of acid-related peptic disease: past, present, and future." Pharmacology & therapeutics 98.1 (2003): 109-127.