Ranitidine (trade name Zantac) is a histamine H2-receptor antagonist that inhibits stomach acid production. It is commonly used in treatment of peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD). Ranitidine is also used alongside fexofenadine and other antihistamines for the treatment of skin conditions such as hives. Ranitidine is also known to give false positives for methamphetamine on drug tests.[1]
Medical use
Certain preparations of ranitidine are not available over the counter (OTC) in various countries. In the United States, 75 mg and 150 mg tablets are available OTC. Zantac OTC is manufactured by Boehringer Ingelheim. In Australia, packs containing 7 or 14 doses of the 150 mg tablet are available in supermarkets, small packs of 150 mg and 300 mg tablets are Schedule 2 Pharmacy Medicines. Larger doses and pack sizes still require a prescription.
Outside the United States and Canada, ranitidine is combined with bismuth (which acts as a mild antibiotic) as a citrate salt (ranitidine bismuth citrate, Tritec), to treat Helicobacter pylori infections. This combination is usually given with clarithromycin, an antibiotic.
Ranitidine's main role is in treating gastric and duodenal ulcers and gastroesophageal reflux disease. It is also used to treat pediatric reflux, where it is preferred over a PPI, because it does not induce histologically relevant hyperplastic changes in the parietal cells. Liquid formulations are available for administering to children.
Ranitidine can also be co-administered with NSAIDs to reduce the risk of ulceration. Proton pump inhibitors are more effective for the prevention of NSAID-induced ulcers.[2]
Ranitidine can be administered preoperatively to reduce the risk of aspiration pneumonia. The drug not only increases gastric pH, but also reduces the total output of gastric juice. Ranitidine may have an antiemetic effect when administered preoperatively.
It can be administered IV in intensive care units to critically ill patients (particularly geriatric ones) to reduce the risk of gastric bleeding.
The usual dose of ranitidine is either 150 mg twice a day or 300 mg once every twenty four hours, usually at night. For ulcer treatment, a 300 mg nighttime dose is especially important - as the increase in gastric/duodenal pH promotes healing overnight when the stomach and duodenum are empty. Conversely, for treating reflux, smaller and more frequent doses are more effective.
Ranitidine used to be administered long term for reflux treatment, sometimes indefinitely. However, PPIs have taken over this role.
In some patients with severe reflux, up to 600 mg of ranitidine can be administered daily, usually in 4 lots of 150 mg. Such a high dose was not unusual in the past, but nowadays a once-a-day PPI is used instead - both for convenience and because they are more effective in raising gastric pH. Patients with Zollinger-Ellison syndrome have been given doses of 6000 mg per day without any harm.
