Cimetidine

Cimetidine: Uses, Dosage and Side Effects

Overview

• Histamine (H2) receptor antagonist, reducing histamine-induced gastric acid secretion.
• Rapidly absorbed with high bioavailability; undergoes hepatic metabolism and renal excretion.
• The plasma half-life is about 2 hours.
• It is not an antiemetic.
• Has weak anti-androgenic effects.

Uses of Cimetidine

• Management of idiopathic, uraemic, or drug-related erosive gastritis, gastric and duodenal ulcers, oesophagitis, and hypersecretory conditions secondary to gastrinoma, mast cell neoplasia, or short bowel syndrome.
• Efficacy against NSAID-induced ulcers is controversial.

Dose of Cimetidine in Dogs and Cats

Dog:

All uses: 5 mg/kg p.o., i.v., i.m. q8h.

Cats:

All uses: 2.5–5 mg/kg p.o., i.v., i.m. q12h

Side Effects of Cimetidine in Dogs and Cats

• Adverse reactions are generally minor even at high doses, but thrombocytopenia has
  been reported in dogs.
• Transient and self-resolving slight swelling of mammary glands may be observed in female dogs.

Contraindications of Cimetidine in Dogs and Cats

No information is available.

Some Notes:

• Rebound gastric acid secretion may be seen on cessation of cimetidine, so therapy should be tapered.
• Concomitant treatment with sucralfate may be helpful.
• If used i.v., should be administered over 30 minutes to prevent cardiac arrhythmias and hypotension.
• Dosage should be reduced for animals with renal impairment.
• Less effective at reducing gastric acidity than more modern H2 blockers and proton pump inhibitors.
• Cimetidine has minimal prokinetic effects.
• Retards oxidative hepatic drug metabolism by binding to the microsomal cytochrome P450.
• May increase plasma levels of beta-blockers (e.g. propranolol), calcium-channel blockers (e.g. verapamil), diazepam, lidocaine, metronidazole, pethidine, and theophylline.
• When used with other agents that cause leucopenia may exacerbate the problem.