Ranitidine

Ranitidine In Dogs & Cats: Uses, Dosage and Side Effects

Overview

• Mechanism of Action: Ranitidine is an H2 receptor antagonist that blocks histamine-induced gastric acid secretion.
• Potency: It is more potent than cimetidine in reducing gastric acid secretion.
• Bioavailability: Ranitidine has lower bioavailability, with only around 50% of the administered dose being absorbed into the bloodstream.
• Metabolism: It undergoes hepatic metabolism in the liver.
• Prokinetic Effect: Ranitidine has some prokinetic effects by stimulating local muscarinic acetylcholine receptors. This property can be beneficial when gastric motility is impaired by conditions like gastritis, ulceration, and feline idiopathic megacolon.

Uses of Ranitidine

• Management of gastric and duodenal ulcers, idiopathic, uraemic or drug-related erosive gastritis, oesophagitis, and hypersecretory conditions secondary to gastrinoma, mast cell neoplasia or short bowel syndrome.
• GI prokinetic effect.

Dose of Ranitidine in Dogs and Cats

Dogs:

• All uses: 2 mg/kg slow i.v., s.c., p.o. q8–12h.

Cats:

• All uses: 2 mg/kg/day constant i.v. infusion, 2.5 mg/kg i.v. slowly q12h, 3.5 mg/kg p.o. q12h.

Side Effects of Ranitidine in Dogs and Cats

• Rarely reported but include cardiac arrhythmias and hypotension, particularly if administered rapidly i.v.

Contraindications of Ranitidine in Dogs and Cats

• No information is available.

Some Notes:

• It is advisable, although not essential, that sucralfate is administered 2 hours before H2 blockers.
• Stagger oral doses of ranitidine when used with other antacids, digoxin or metoclopramide by 2 hours as it may reduce their absorption or effect.