Ranitidine, Uses, Dosage, Side Effects, Interactions, Pregnancy

Ranitidine, Uses, Dosage, Side Effects, Interactions, Pregnancy

Ranitidine is a member of the class of histamine H2-receptor antagonists with antacid activity. Ranitidine is a competitive and reversible inhibitor of the action of histamine, released by enterochromaffin-like (ECL) cells, at the histamine H2-receptors on parietal cells in the stomach, thereby inhibiting the normal and meal-stimulated secretion of stomach acid. In addition, other substances that promote acid secretion have a reduced effect on parietal cells when the H2 receptors are blocked.

Ranitidine is a histamine type 2 receptor antagonist (H2 blocker) which is widely used for treatment of acid-peptic disease and heartburn. Ranitidine has been linked to rare instances of clinically apparent acute liver injury. Ranitidine is a non-imidazole blocker of those histamine receptors that mediate gastric secretion (H2 receptors) & oral drug that blocks the production of acid by acid-producing cells in the stomach.

Mechanism of Action of Ranitidine

The H2 antagonists are competitive inhibitors of histamine at the parietal cell H2 receptor. They suppress the normal secretion of acid by parietal cells and the meal-stimulated secretion of acid. They accomplish this by two mechanisms: histamine released by ECL cells in the stomach is blocked from binding on parietal cell H2 receptors which stimulate acid secretion, and other substances that promote acid secretion (such as gastrin and acetylcholine) have a reduced effect on parietal cells when the H2 receptors are blocked.
H2 antagonists inhibit gastric acid secretion elicited by histamine and other H2 agonists in a dose dependent, competitive manner; the degree of inhibition parallels the concentration of the drug in plasma over a wide range. The H2 antagonists also inhibit acid secretion elicited by gastrin and, to a lesser extent, by muscarinic agonists. Importantly, these drugs inhibit basal (fasting) and nocturnal acid secretion and that stimulated by food, sham feeding, fundic distention, and various pharmacological agents; this property reflects the vital role of histamine in mediating the effects of diverse stimuli. 

Indications of Ranitidine

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Therapeutic of Ranitidine

  • Anti-Ulcer Agents
  • Ranitidine is effective for the treatment of duodenal or gastric ulcer and relieves symptoms of reflux esophagitis. It heals some NSAID-induced ulcers but does not appear to prevent their initial occurrence.
  • Investigationally, this drug prevented aspiration pneumonitis during surgery, and it appears to be useful for the prophylaxis of bleeding due to stress ulcers.
  • Studies show that ranitidine can adequately inhibit acid secretion in patients with gastric hypersecretory disorders, is safe at high doses, does not cause the antiandrogen side effects frequently seen with high doses of cimetidine, & is threefold more potent than cimetidine. Patients relatively resistant to cimetidine will have proportional resistance to ranitidine.
  • Ranitidine and a placebo were evaluated in the 28 day treatment of duodenal ulcer through an open randomized study performed in 120 patients. At the end of the treatment, ranitidine demonstrated a significantly higher efficacy on ulcer healing as well as on symptom relief in comparison with placebo .
  • Parenteral ranitidine is used to prevent and treat upper gastrointestinal, stress-induced ulceration and bleeding, especially in intensive care patients. However, the efficacy of histamine H2-receptor antagonists in treating hemorrhage in critically ill patients has not been established.
  • Histamine H2-receptor antagonists are indicated in the short-term treatment of active duodenal ulcer. They are also indicated (at reduce dosage) in the prevention of duodenal ulcer recurrence in selected patients.
  • Ranitidine is indicated in the short-term treatment of active benign gastric ulcer.
  • Rantidine is indicated in the treatment of pathological gastric hypersecretion associated with Zollinger-Ellison syndrome (alone or as part of multiple endocrine neoplasia Type-1), systemic mastocytosis, and multiple endocrine adenoma.
  • Ranitidine is indicated in the treatment of acute gastroesophageal reflux disease, which may or may not cause erosion or ulcerative esophagitis.
  • Ranitidine is used to treat upper gastrointestinal bleeding secondary to gastric ulcer, duodenal ulcer, or hemorrhagic gastritis.
  • Histamine H2-receptor antagonists are not recommended for minor digestive complaints.
  • Ranitidine is also used before anesthesia induction for the prophylaxis of aspiration pneumonitis.
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Contra Indications of Ranitidine

Side Effects of Ranitidine

The most common



Drug Interactions of Ranitidine

Ranitidine may interact with following drugs, supplyments, & may change the efficacy of drugs

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Pregnancy Category Ranitidine

FDA Pregnancy Category BPregnancy

Studies in animals have failed to demonstrate a risk to the unborn baby, and there are no well-controlled studies in pregnant women. Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have not shown evidence of an increased occurrence of fetal damage.


Tell your doctor if you are breastfeeding or plan to breastfeed. The active ingredient in ranitidine is excreted in human breast milk. The effect of ranitidine on the nursing infant is not known.





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