Active ingredient: Cimetidine - Brands, Medical Use, Clinical Data

Brands, Medical Use, Clinical Data

Drug Category

• Analgesics
• Anti-ulcer Agents
• Adjuvants
• Histamine Antagonists

Dosage Forms

• Tablets
• Oral solution

Brands / Synonyms

Acibilin; Acinil; Carbamazapine; Cimal; Cimetag; CIMETIDINE A/AB; Cimetidine Hcl; Cimetum; Dyspamet; Edalene; Eureceptor; Gastromet; Peptol; Tagamet; Tagamet Hb; Tagamet Hb 200; Tametin; Tratul; Ulcedin; Ulcedine; Ulcerfen; Ulcimet; Ulcofalk; Ulcomedina; Ulcomet; Ulhys

Indications

For the treatment and the management of acid-reflux disorders (GERD), peptic ulcer disease, heartburn, and acid indigestion

Pharmacology

Cimetidine is a histamine H₂-receptor antagonist. It reduces basal and nocturnal gastric acid secretion and a reduction in gastric volume, acidity, and amount of gastric acid released in response to stimuli including food, caffeine, insulin, betazole, or pentagastrin. It is used to treat gastrointestinal disorders such as gastric or duodenal ulcer, gastroesophageal reflux disease, and pathological hypersecretory conditions. Cimetidine inhibits many of the isoenzymes of the hepatic CYP450 enzyme system. Other actions of Cimetidine include an increase in gastric bacterial flora such as nitrate-reducing organisms.

Mechanism of Action

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.

Absorption

Rapid 60-70%

Toxicity

nausea, vomiting, diarrhea, increased saliva production, difficulty breathing, and a fast heartbeat.

Biotrnasformation / Drug Metabolism

Hepatic

Contraindications

Tagamet is contraindicated for patients known to have hypersensitivity to the product.

Drug Interactions

Tagamet, apparently through an effect on certain microsomal enzyme systems, has been reported to reduce the hepatic metabolism of warfarin-type anticoagulants, phenytoin, propranolol, nifedipine, chlordiazepoxide, diazepam, certain tricyclic antidepressants, lidocaine, theophylline and metronidazole, thereby delaying elimination and increasing blood levels of these drugs.

Clinically significant effects have been reported with the warfarin anticoagulants; therefore, close monitoring of prothrombin time is recommended, and adjustment of the anticoagulant dose may be necessary when Tagamet is administered concomitantly. Interaction with phenytoin, lidocaine and theophylline has also been reported to produce adverse clinical effects.

However, a crossover study in healthy subjects receiving either Tagamet 300 mg q.i.d. or 800 mg h.s. concomitantly with a 300 mg b.i.d. dosage of theophylline (Theo-Dur^®, Key Pharmaceuticals, Inc.) demonstrated less alteration in steady-state theophylline peak serum levels with the 800 mg h.s. regimen, particularly in subjects aged 54 years and older. Data beyond 10 days are not available. (Note: All patients receiving theophylline should be monitored appropriately, regardless of concomitant drug therapy.)

Dosage of the drugs mentioned above and other similarly metabolized drugs, particularly those of low therapeutic ratio or in patients with renal and/or hepatic impairment, may require adjustment when starting or stopping concomitantly administered Tagamet to maintain optimum therapeutic blood levels.

Alteration of pH may affect absorption of certain drugs (e.g., ketoconazole). If these products are needed, they should be given at least 2 hours before cimetidine administration.

Additional clinical experience may reveal other drugs affected by the concomitant administration of Tagamet.