Ranitidine was discovered in 1976, and came into commercial use in 1981. It is on the World Health Organization's List of Essential Medicines, the safest and most effective medicines needed in a health system. It is available as a generic medication. The 2015 wholesale price in the developing world was about US$0.01–0.05 per pill. In the United States it is about $0.05 per dose. In 2016, it was the 50th most prescribed medication in the United States with more than 15 million prescriptions. In September 2019, the toxin N-nitrosodimethylamine was discovered to occur in ranitidine from a number of manufacturers, resulting in distribution stops and recalls.
Part of a multidrug regimen for Helicobacter pylori eradication to reduce the risk of duodenal ulcer recurrence
Recurrent postoperative ulcer
Upper GI bleeding
Prevention of acid-aspiration pneumonitis during surgery: ranitidine can be administered preoperatively to reduce the risk of aspiration pneumonia. The drug increases gastric pH, but generally has no effect on gastric volume. In a 2009 meta-analysis comparing the net benefit of proton pump inhibitors and ranitidine to reduce the risk of aspiration before anesthesia, ranitidine was found to be more effective than proton pump inhibitors in reducing the volume of gastric secretions. Ranitidine may have an antiemetic effect when administered preoperatively.
Certain preparations of ranitidine are available over the counter (OTC) in various countries. In the United States, 75- and 150-mg tablets are available OTC. Since 2017, Zantac is marketed in the U.S. by Sanofi. In Australia and the UK, packs containing seven 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 require a prescription.
For ulcer treatment, a night-time 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.[medical citation needed]
Ranitidine used to be administered long-term for reflux treatment, sometimes indefinitely. However, proton-pump inhibitors (PPIs) have taken over this role. In addition, a fairly rapid tachyphylaxis can develop within six weeks of initiation of treatment, further limiting its potential for long-term use.
Ranitidine is contraindicated for patients known to have hypersensitivity to the drug.
The following adverse effects have been reported as events in clinical trials:
Central nervous system
Rare reports have been made of malaise, dizziness, somnolence, insomnia, and vertigo. In severely ill, elderly patients, cases of reversible mental confusion, agitation, depression, and hallucinations have been reported. Ranitidine causes fewer CNS adverse reactions and drug interactions compared with cimetidine.
All drugs in its class have the potential to cause vitamin B12 deficiency secondary to a reduction in food-bound vitamin B12 absorption. Elderly patients taking H2 receptor antagonists are more likely to require B12 supplementation than those not taking such drugs. H2 blockers may also reduce the absorption of drugs (azole antifungals, calcium carbonate) that require an acidic stomach. In addition, multiple studies suggest the use of H2 receptor antagonists such as raniditine may increase the risk of infectious diarrhoea, including traveller's diarrhoea and salmonellosis. A 2005 study found that by suppressing acid-mediated breakdown of proteins, ranitidine may lead to an elevated risk of developing food or drug allergies, due to undigested proteins then passing into the gastrointestinal tract, where sensitisation occurs. Patients who take these agents develop higher levels of immunoglobulin E against food, whether they had prior antibodies or not. Even months after discontinuation, an elevated level of IgE in six percent of patients was still found in the study.[medical citation needed]
Ranitidine and other histamine H2 receptor antagonists may increase the risk of pneumonia in hospitalized patients. They may also increase the risk of community-acquired pneumonia in adults and children.
Thrombocytopenia is a rare but known side effect. Drug-induced thrombocytopenia usually takes weeks or months to appear, but may appear within 12 hours of drug intake in a sensitized individual. Typically, the platelet count falls to 80% of normal, and thrombocytopenia may be associated with neutropenia and anemia.
Relief of symptoms due to the use of ranitidine does not exclude the presence of a gastric malignancy. In addition, with kidney or liver impairment, ranitidine must be used with caution. Ranitidine should be avoided in patients with porphyria, as it may precipitate an attack.
Ranitidine enters breast milk, with peak concentrations seen at 5.5 hours after the dose in breast milk. Caution should be exercised when prescribed to nursing women.
In children, the use of gastric acid inhibitors has been associated with an increased risk for development of acute gastroenteritis and community-acquired pneumonia. A cohort analysis including over 11,000 neonates reported an association of H2 blocker use and an increased incidence of necrotizing enterocolitis in very-low-birth-weight (VLBW) neonates. In addition, about a sixfold increase in mortality, necrotizing enterocolitis, and infection (such as sepsis, pneumonia, urinary tract infection) was reported in patients receiving ranitidine in a cohort analysis of 274 VLBW neonates.
Ranitidine may return a false positive result with some commercial kits for testing for drugs of abuse.
In September 2019, the U.S. Food and Drug Administration (FDA) learned that some ranitidine medicines, including some products sold under the brand name Zantac, contained a nitrosamine impurity called N-nitrosodimethylamine (NDMA), classified as a probable human carcinogen, at low levels. Health Canada announced that it was assessing NDMA in ranitidine and requested that manufacturers stop the distribution of ranitidine products in Canada until the NDMA levels in the products are found to be safe. Health Canada announced that ranitidine drugs were being recalled by Sandoz Canada, Apotex Inc., Pro Doc Limitée, Sanis Health Inc., and Sivem Pharmaceuticals ULC. The European Medicines Agency (EMA) started an EU-wide review of ranitidine medicines at the request of the European Commission.
In September 2019, Sandoz issued a "precautionary distribution stop" of all medicines containing ranitidine. followed a few days later by a recall of ranitidine hydrochloride capsules in the United States. The Italian Medicines Agency, AIFA, recalled all ranitidine that uses an active pharmaceutical ingredient (API) from Saraca Laboratories. The German Pharmacists Committee (AMK) published a list of recalled products. The Therapeutic Goods Administration (TGA) in Australia published a list of recalled products.
In September 2019, Apotex recalled all over-the-counter (OTC) ranitidine tablets sold in the United States at Walmart, Rite Aid, and Walgreens. Subsequently, Walmart, Rite Aid, Walgreens, and CVS pulled Zantac and some generics from their shelves.
In October 2019, the U.S. Food and Drug Administration (FDA) observed that a third-party laboratory was using higher temperatures in its tests to look for nitrosamine impurities. The NDMA was generated by the added heat but the higher temperatures were recommended for using a gas chromatography–mass spectrometry (GC/MS) method to test for NDMA in valsartan and angiotensin II receptor blockers (ARBs). The FDA stated that it recommends using a liquid chromatography-high resolution mass spectrometry (LC-HRMS) testing protocol to test samples of ranitidine. Its LC-HRMS testing method does not use elevated temperatures and has shown the presence of much lower levels of NDMA in ranitidine medicines than reported by the third-party laboratory. International regulators using similar LC-MS testing methods have also shown the presence of low levels of NDMA in ranitidine samples.
In October 2019, Sanofi recalled all over-the-counter Zantac in the United States and Canada.
Mechanism of action
Ranitidine is a competitive, reversible inhibitor of the action of histamine at the histamine H2 receptors found in gastric parietal cells. This results in decreased gastric acid secretion and gastric volume, and reduced hydrogen ion concentration.[medical citation needed]
Absorption: Oral: 50%
Protein binding: 15%
Metabolism: N-oxide is the principal metabolite.
Half-life elimination: With normal renal function, ranitidine taken orally has a half-life of 2.5–3.0 hours. If taken intravenously, the half-life is generally 2.0–2.5 hours in a patient with normal creatinine clearance.
Excretion: The primary route of excretion is the urine. In addition, about 30% of the orally administered dose is collected in the urine as non-absorbed drug in 24 hours.
In the elderly population, the plasma half-life of ranitidine is prolonged to 3–4 hours secondary to decreased kidney function causing decreased clearance.
In general, studies of pediatric patients (aged one month to 16 years) have shown no significant differences in pharmacokinetic parameter values in comparison to healthy adults, when correction is made for body weight.
Zantac (ranitidine) 300-mg tablets
Ranitidine was first prepared as AH19065 by John Bradshaw in the summer of 1977 in the Ware research laboratories of Allen & Hanburys, part of the Glaxo organization. Its development was a response to the first in class histamine H2 receptor antagonist, cimetidine, developed by Sir James Black at Smith, Kline and French, and launched in the United Kingdom as Tagamet in November 1976. Both companies would eventually become merged as GlaxoSmithKline following a sequence of mergers and acquisitions starting with the integration of Allen & Hanbury's Ltd and Glaxo to form Glaxo Group Research in 1979, and ultimately with the merger of Glaxo Wellcome and SmithKline Beecham in 2000. Ranitidine was the result of a rational drug-design process using what was by then a fairly refined model of the histamine H2 receptor and quantitative structure-activity relationships.
Glaxo refined the model further by replacing the imidazole ring of cimetidine with a furan ring with a nitrogen-containing substituent, and in doing so developed ranitidine. Ranitidine was found to have a far-improved tolerability profile (i.e. fewer adverse drug reactions), longer-lasting action, and 10 times the activity of cimetidine. Ranitidine has 10% of the affinity that cimetidine has to CYP450, so it causes fewer side effects, but other H2 blockers famotidine and nizatidine have no CYP450 significant interactions.
Ranitidine was introduced in 1981, and was the world's biggest-selling prescription drug by 1987. It was largely superseded by the even more effective proton-pump inhibitors, with omeprazole becoming the biggest-selling drug for many years. When omeprazole and ranitidine were compared in a study of 144 people with severe inflammation and erosions or ulcers of the esophagus, 85% of those treated with omeprazole healed within eight weeks, compared with 50% of those given ranitidine. In addition, the omeprazole group reported earlier relief of heartburn symptoms.
Famotidine (trade names Pepcid, Pepcidine) — another popular H2 receptor antagonist
^ abGardner JD, Ciociola AA, Robinson M, et al. (July 2002). "Determination of the time of onset of action of ranitidine and famotidine on intra-gastric acidity". Aliment. Pharmacol. Ther. 16 (7): 1317–1326. doi:10.1046/j.1365-2036.2002.01291.x. PMID12144582.
^Clark K, Lam LT, Gibson S, et al. (2009). "The effect of ranitidine versus proton pump inhibitors on gastric secretions: a meta-analysis of randomised control trials". Anaesthesia. 64 (6): 652–657. doi:10.1111/j.1365-2044.2008.05861.x. PMID19453319.
^Lightdale JR, Gremse DA, Section on Gastroenterology, Hepatology, and Nutrition (2013). "Gastroesophageal reflux: management guidance for the pediatrician". Pediatrics. 131 (5): e1684–e1695. doi:10.1542/peds.2013-0421. PMID23629618.
^Cobelens FG, Leentvarr-Kuijpers A, Kleijnen J, et al. (November 1998). "Incidence and risk factors of diarrhoea in Dutch travellers: Consequences for priorities in pre-travel health advice". Trop Med Intern Health. 3 (11): 896–903. PMID9855403.
^Canani RB, Cirillo P, Roggero P, et al. (2006). "Therapy with gastric acidity inhibitors increases the risk of acute gastroenteritis and community-acquired pneumonia in children". Pediatrics. 117 (5): e817–20. doi:10.1542/peds.2005-1655. PMID16651285.
^Guillet R, Stoll BJ, Cotten CM, et al. (2006). "Association of H2-blocker therapy and higher incidence of necrotizing enterocolitis in very low birth weight infants". Pediatrics. 117 (2): e137–42. doi:10.1542/peds.2005-1543. PMID16390920.
^Terrin G, Passariello A, De Curtis M, et al. (2012). "Ranitidine is associated with infections, necrotizing enterocolitis, and fatal outcome in newborns". Pediatrics. 129 (1): 40–5. doi:10.1542/peds.2011-0796. PMID22157140.
^Brahm NC, Yeager LL, Fox MD, et al. (15 August 2010). "Commonly prescribed medications and potential false-positive urine drug screens". Am J Health Syst Pharm. 67 (16): 1344–50. doi:10.2146/ajhp090477. PMID20689123.
^"FDA Updates and Press Announcements on NDMA in Zantac (ranitidine)". Food and Drug Administration (FDA). 2 October 2019. Archived from the original on 3 October 2019. Retrieved 2 October 2019. FDA observed the testing method used by a third-party laboratory uses higher temperatures. The higher temperatures generated very high levels of NDMA from ranitidine products because of the test procedure. FDA published the method for testing angiotensin II receptor blockers (ARBs) for nitrosamine impurities. That method is not suitable for testing ranitidine because heating the sample generates NDMA. FDA recommends using an LC-HRMS testing protocol to test samples of ranitidine. FDA's LC-HRMS testing method does not use elevated temperatures and has shown the presence of much lower levels of NDMA in ranitidine medicines than reported by the third-party laboratory. International regulators using similar LC-MS testing methods have also shown the presence of low levels of NDMA in ranitidine samples.This article incorporates text from this source, which is in the public domain.
^Pelot, Daniel, (M.D.). "Digestive System : New Drug for Heartburn". The New Book of Knowledge : Medicine & Health, Grolier : Danbury, Connecticut. 1990. p.262. ISBN0-7172-8244-9. Library of Congress 82-645223
^Yeomans ND, Tulassay Z, Juhász L, et al. (March 1998). "A comparison of omeprazole with ranitidine for ulcers associated with nonsteroidal antiinflammatory drugs. Acid Suppression Trial: Ranitidine versus Omeprazole for NSAID-associated Ulcer Treatment (ASTRONAUT) Study Group". N. Engl. J. Med. 338 (11): 719–26. doi:10.1056/NEJM199803123381104. PMID9494148.