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Acid-Peptic Drugs
Drugs for Acid & peptic related diseases
Question | Answer |
---|---|
Types of PUD & common causes. | Gastric and duodenal ulcers caused by NSAID use and H. pylori infection. GERD can be caused by abnormal LES relaxation. |
Drugs that reduce acidity of stomach & their examples (3) | Antacids: Alkaseltzer (NaHCO3 content) & Gaviscon (Al + Mg content). H2-receptor antagonist: Cimetidine, Ranitidine. Proton-pump inhibitors (PPI): omeprazole, esomeprazole. |
Antacids: constituents and mode of action | Consists weak acids such as NaHCO3, CaCO3, MgOH, AlOH. Neutralises already-produced gastric acid to form salt and water. Some formulas contain simethicone which eases CO2 release within GIT, preventing bloating. |
Antacids: uses | OTC: heartburn and dyspepsia. Mg+Al combined formulas usually used as it has least side effects (diarrhea + constip), even though it is slowest. |
Antacids: toxicity | Long term Na antacids can lead to fluid retention and congestive HF. Often affects absorption of other medications, so should not be taken within 2h of certain drugs like tetracyclin and iron (chelates). Patients w/ renal insufficiency should not use. |
H2 receptor antagonist (H2 blocker): mode of action | Very safe drug that inhibits 60-70% of total 24h gastric secretion. This is done by competitively inhibiting H2 receptors on parietal cells to suppress gastric acid secretion and pepsin concentration induced by histamine, gastrin and acetylcholine. |
H2 receptor antagonist (H2 blocker): uses | Average effect on meal-induced acid secretion (since it only blocks H2 receptors) but very effective at inhibiting noctornal acid secretion (mostly induced by histamine) |
H2 receptor antagonist (H2 blocker): toxicity | Very safe drug w minimal side effects. Cimetidine has side effects like galactorrhea, gynecomastia since it is anti-estrogenic. It also inhibits cytochrome p450, therefore prolonging half life of other drugs. So, ranitidine is used instead. |
PPI: mode of action | Inactive pro-drugs in enteric coated formula -> released and absorbed in intestines -> activated and concentrated in parietal cells. Inhibits H/K ATPase pump by forming covalent disulphide bond - irreversible. |
PPI: uses | Used in dyspepsia, and only inactivates actively working pumps. Does not inhibit quiescent pumps. Takes 3-4 days to fully inhibit acid secretion by blocking all pumps. It has some anti microbial activity against H. pylori. Gastric pH rises to 3-4. |
PPI: toxicity & example | Extremely safe with minor effects: headache, nausea, constipation, flatulence etc. Example = omeprazole, esomeprazole. |