Medications Affecting Gastric Secretion

Medications Affecting Gastric Secretion

• Magnesium hydroxide, Aluminium hydroxide gel: Neutralize gastric secretions. May cause diarrhea. Used for ruminal acidosis, gastritis, and esophagitis.
• Sucralfate: Protects stomach mucosa. May interfere with absorption of other drugs absorbed through the stomach lining.
• Activated charcoal, Bismuth, Kaolin/pectin: Absorb toxins; coat the stomach and bind to bacteria/toxins.
• Ranitidine, Cimetidine: Histamine antagonists; inhibit gastrin, histamine, and acetylcholine-stimulated secretion. Pepsin secretion reduced. Rebound increase possible on withdrawal. Cimetidine inhibits cytochrome P450 and slows metabolism.
• Omeprazole, Lansoprazole: Proton pump inhibitors, irreversibly bind to ATPase, inhibiting both basal and stimulated acid release.
• Misoprostol: Stable analogue of PGE1. Inhibits acid secretion, increases mucosal blood flow, and increases uterine contractions. Do not use in late gestation due to risk of premature labor/abortion.

Emetics

• Apomorphine: Dopamine agonist causing vomiting. Used IV or mucosal, rapid effect. May cause psychomotor effects in cats.
• Xylazine: Alpha 2 agonist used as an emetic.
• Syrup of Ipecac: Direct irritant causing vomiting. High doses can cause cardiotoxicity.
• Chlorpromazine: Dopamine antagonist (centrally acting) antiemetic.
• Metoclopramide, Domperidone: Dopamine antagonists. Contraindicated if vomiting is due to obstruction. IV administration; short-acting.
• Maropitant (Cerenia): Neurokinin-1 antagonist. Competes with substance P. Specifically designed for dogs but also used in cats.

Antimotility Agents

• Opiates (Morphine, Codeine, Loperamide): Increase contractions but decrease propulsion, leading to increased large intestine tone (constipation). Can cause diarrhea, colic, and stasis.
• Atropine, Hyoscine (Buscopan): Inhibit acetylcholine stimulating effects from vagus nerve. Atropine not as specific. Used for diarrhea, colic, and stasis.

Laxatives

• Methylcellulose, Agar bran: Increase GIT bulk to stimulate motility.
• Lactulose: Broken down in the lower gut to lactic acid, altering pH to more acidic, trapping ammonia and consequently water.

Motility Agent

• Cisapride: Serotonergic 5-HT4 receptor agonist.

Digestive Enzymes

• Porcine pancreatic enzymes: Used for exocrine pancreatic insufficiency.

Other

• Prednisolone: Anti-inflammatory agent.
• Bloat Guard (surfactant): Antifoaming agent. Detergent action breaks down bubbles. Used in ruminants (frothy bloat).