Last Updated on January 4, 2021 by Julia Wilson
Zantac (ranitidine) is an over the counter medication in the family of histamine H2 receptor blockers (antagonist). It works by preventing the binding of histamine at the receptor on the parietal cells in the stomach, reducing gastric acid output. Zantac also has prokinetic properties, which enhances gastric motility (contractions of the smooth muscles in the gastrointestinal tract).
This drug is not approved by the FDA for use in cats and is prescribed as an extra-label drug by veterinarians.
- Treat and prevent gastric ulcers
- Gastritis (inflammation of the stomach)
- Esophagitis (inflammation of the esophagus)
- Duodenal and esophageal gastric reflux
- Gastric motility disorders including megacolon
- Zantac may be prescribed in cats with mast cell tumours which produce large amounts of histamine
How is Zantac supplied?
Zantac comes in tablet, effervescent tablets, granules, syrup or injection.
Tablets come in 75, 150 and 300 mg doses.
Store in a light-resistant container at room temperature. Keep out of reach of children and pets and where possible, keep pet medications separate from human medications.
Injectible Zantac should be stored in a refrigerator.
What should I do if I miss a dose?
Administer as soon as possible; however, if it is close to the time for your cat’s next dose, do not administer, wait until the scheduled time. Never exceed the total stated dose.
What should I do if the cat receives an overdose?
Contact your veterinarian immediately. For safety, one person should be responsible for administering medication to reduce the chances of doubling up.
The most common side effect is pain at the injection site if the drug is administered via injection.
Rare side effects include:
- Transient cardiac arrhythmias
What if my cat is taking other drugs?
Tell your veterinarian if your cat is on any other medication or supplements as Zantac may interact with them.
Antacids can decrease absorption of Zantac, therefore if your cat is also taking antacids as well as Zantac, administer at separate times, two hours apart.
Ketoconazole and itraconazole are anti-fungal medications which are absorbed in the acidic environment of the stomach, as acid production is altered in cats taking Zantac, the effectiveness of these medications may be reduced.
Do not give Zantac to cats who are sensitive or allergic to the drug.
Use with care, and possibly at a reduced dose in cats with diminished kidney or liver function. Your veterinarian may recommend close monitoring of liver enzymes.
Do not give Zantac to lactating cats.
Never administer any medication or supplement unless prescribed by a veterinarian.
The recommended dose is 3.5 mg per kilo every 12 hours.
Always follow your veterinarian’s instructions and avoid the following:
- Giving a larger dose than prescribed
- Administering ranitidine more often than prescribed
- Skipping a dose
Other drugs in the same class as ranitidine include:
- Famotidine (Pepcid)
- Nizatidine (Axid)
- Cimetidine (Tagamet)
One trial in humans found that the duration of action of famotidine (Pepcid) was 30 percent longer than that of either Tagamet or Zantac. Pepcid was nine times more potent than Zantac and 32 times more potent than Tagamet.