Ranitidine

Indications

• • peptic ulcer disease (PUD)

  • gastroesophageal reflux disease (GERD

  • alongside fexofenadine and other antihistamines for the treatment of skin conditions such as hives

  • Protection against aspirin-induced GI irritation

Administration/Absorption

Dosage

• • 150 mg twice a day or 300 mg once every twenty four hours, usually at night

Distribution

Mechanism

• • histamine H₂-receptor antagonist

    • Competitive antagonist of histamine at the parietal cell H₂ receptor.

  • Suppress the normal secretion of acid by parietal cells and the meal-stimulated secretion of acid.

    • Histamine released by ECL cells in the stomach is blocked from binding on parietal cell H₂ receptors, which stimulate acid secretion

    • Therefore, other substances that promote acid secretion (such as gastrin and acetylcholine) have a reduced effect on parietal cells when the H₂ receptors are blocked.

  • Like the H₁-antihistamines, the H₂ antagonists are inverse agonists rather than true receptor antagonists.

Excretion

Side effects

• • confusion and depression, although these are very rare and usually only seen in geriatric patients

Interactions

Contraindications