Cimetidine; Uses, Dosage, Side Effects, Drug Interactions

Cimetidine








User Review


5
(3 votes)


Cimetidine is a histamine H2 receptor antagonist that inhibits stomach acid production. It inhibits gastric acid secretion, as well as pepsin and gastrins output. It is available over-the-counter and is mainly used in the treatment of heartburn and peptic ulcers. The development of longer-acting H2 receptor antagonists with fewer drug interactions and adverse effects, such as ranitidine and famotidine, decreased the use of cimetidine, and though it is still used, cimetidine is no longer among the more widely used of the H2-receptor antagonists.

Mechanism of Action of Cimetidine

Cimetidine binds to an H2-receptor located on the basolateral membrane of the gastric parietal cell, blocking histamine effects. This competitive inhibition results in reduced gastric acid secretion and a reduction in gastric volume and acidity.

H2 antagonists inhibit gastric acid secretion elicited by histamine & 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 &, to a lesser extent, by muscarinic agonists. Importantly, these drugs inhibit basal (fasting) & nocturnal acid secretion & that stimulated by food, sham feeding, fundic distention, & various pharmacological agents; this property reflects the vital role of histamine in mediating the effects of diverse stimuli. The H2 antagonists reduce both the volume of gastric juice secreted & its H+ concentration. The output of pepsin, which is secreted by the chief cells of gastric glands (mainly under cholinergic control), generally falls in parallel with the reduction in the volume of gastric juice. Cimetidine blocks H2-receptors, which in part are responsible for the inflammatory response, in the cutaneous blood vessels of humans.

Indications of Cimetidine

Contra-Indications of Cimetidine

Dosage of Cimetidine

Strengths: 100 mg; 200 mg; 300 mg; 400 mg; 800 mg;  900 mg 300 mg/5 mL;

Duodenal Ulcer

  • Parenteral: 300 mg IV or IM every 6 to 8 hours. Alternatively, a continuous IV infusion may be administered at a rate of 37.5 to 50 mg/hour, or up to a maximum rate of 100 mg/hour (2.4 g/day).
  • Oral: 800 mg to 1600 mg once a day at bedtime. Alternatively, dosage regimens of 300 mg four times per day, with meals and at bedtime, or 400 mg twice daily, in the morning and at bedtime, have shown to be effective.

Erosive Esophagitis

  • Parenteral: 300 mg IV or IM every 6 hours. Alternatively, a continuous IV infusion may be administered at a rate of 50 mg/hour initially, with 25 mg/hour incremental increases up to a maximum rate of 100 mg/hour (2.4 g/day).
  • Oral: 800 mg twice a day, or alternatively, 400 mg four times a day.

Stress Ulcer Prophylaxis

  • Parenteral: 300 mg IV or IM every 6 hours. Alternatively, a continuous IV infusion may be administered at a rate of 50 mg/hour.

Zollinger-Ellison Syndrome

  • Parenteral: 300 mg IV or IM every 6 hours. Alternatively, a continuous IV infusion may be administered at a rate of 50 mg/hour initially. Infusion rates have ranged from 40 to 600 mg/hour, but should not exceed a daily total of 2.4 g.
  • Oral: 300 mg 4 times a day with meals and at bedtime.

Gastroesophageal Reflux Disease

  • Parenteral: 300 mg IV or IM every 6 hours. Alternatively, a continuous IV infusion may be administered at a rate of 50 mg/hour. The maximum daily dose should not exceed 2.4 g.
  • Oral: 800 mg twice a day, or 400 mg 4 times a day.

Pediatric Gastroesophageal Reflux Disease

  • Neonatal: 5 to 10 mg/kg/day administered IV or IM in divided doses every 8 to 12 hours.
  • Infants: 10 to 20 mg/kg/day administered IV, IM, or oral in divided doses every 6 to 12 hours.
  • Children: 20 to 40 mg/kg/day administered IV, IM, or oral in divided doses every 6 hours.

Side Effects of Cimetidine

The most common

More common

Rare

Drug Interactions of Cimetidine

Cimetidine may interact with the following drugs, supplements, & may change the efficacy of the drug

Pregnancy Catagory

FDA Pregnancy Category C

Pregnancy

The safety of this medication for use during pregnancy has not been established. This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Lactation

This medication passes into breast milk. If you are a breastfeeding mother and are taking cimetidine, it may affect your baby. Talk to your doctor about whether you should continue breastfeeding.

References

Cimetidine

Print Friendly, PDF & Email

Sharing to Spread to the World

Leave a Reply

Your email address will not be published.