Used in the treatment of peptic ulcer disease (PUD), dyspepsia, stress ulcer prophylaxis, and gastroesophageal reflux disease (GERD).
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.
LD<sub>50</sub>=77mg/kg (orally in mice). Symptoms of overdose include muscular tremors, vomiting, and rapid respiration.
Approximately 50% bioavailability orally.
2.8-3.1 hours
The principal route of excretion is the urine (active tubular excretion, renal clearance 410mL/min), with approximately 30% of the orally administered dose collected in the urine as unchanged drug in 24 hours.
* 1.4 L/kg * 1.76 L/kg [clinically significant renal function impairment (creatinine clearance 25 to 35 mL/min)]
* 29 mL/min [clinically significant renal function impairment] * 3 mL/min/Kg [neonatal patients]