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an antagonist of histamine H2receptors, inhibiting the action of histamine at cell surface receptors of the gastric parietal cells and reducing basal gastric acid secretion and secretion stimulated by food, histamine, gastrin, caffeine, and insulin. It is used for the short-term (two months) treatment and, at reduced dosage, the long-term prevention of peptic ulcers, for the relief of symptoms associated with hyperacidity, such as heartburn and acid indigestion, and for the treatment of gastroesophageal reflux disease, upper gastrointestinal bleeding, and pathological hypersecretory conditions such as zollinger-ellison syndrome. Treatment of peptic ulcer with cimetidine brings prompt relief and speeds ulcer healing. Antacids are also taken as needed for relief of pain. Cimetidine is used as the base or the hydrochloride salt, administered orally, intramuscularly, or intravenously.


Apo-Cimetidine (CA), Dyspamet (UK), Galenmet (UK), Novo-Cimetine (CA), Nu-Cimet (CA), Tagamet HB

Pharmacologic class: Histamine2-receptor antagonist

Therapeutic class: Antiulcer drug

Pregnancy risk category B


Competitively inhibits histamine action at histamine2-receptor sites of gastric parietal cells, thereby inhibiting gastric acid secretion


Oral liquid: 200 mg/5 ml, 300 mg/5 ml

Tablets: 200 mg, 300 mg, 400 mg, 600 mg, 800 mg

Indications and dosages

Active duodenal ulcer (short-term therapy)

Adults and children older than age 16: 800 mg P.O. at bedtime, or 300 mg P.O. q.i.d. with meals and at bedtime, or 400 mg P.O. b.i.d. Maintenance dosage is 400 mg P.O. at bedtime.

Active benign gastric ulcer (short-term therapy)

Adults and children older than age 16: 800 mg P.O. at bedtime or 300 mg P.O. q.i.d. with meals and at bedtime

Gastric hypersecretory conditions (such as Zollinger-Ellison syndrome); intractable ulcers

Adults and children older than age 16: 300 mg P.O. q.i.d. with meals and at bedtime

Erosive gastroesophageal reflux disease

Adults and children older than age 16: 1,600 mg P.O. daily in divided doses (800 mg b.i.d. or 400 mg q.i.d.) for 12 weeks

Heartburn; acid indigestion

Adults and children older than age 16: 200 mg (two tablets of over-the-counter product only) P.O. up to b.i.d. Give maximum dosage no longer than 2 weeks continuously, unless directed by prescriber.

Dosage adjustment

• Renal impairment

Off-label uses

• Acetaminophen overdose

• Adjunctive therapy in burns

• Barrett's esophagus

• Renal cancer

• Anaphylaxis


• Hypersensitivity to drug

• Alcohol intolerance


Use cautiously in:

• renal impairment

• elderly patients

• pregnant or breastfeeding patients.


• Give with meals.

Adverse reactions

CNS: confusion, dizziness, drowsiness, hallucinations, agitation, psychosis, depression, anxiety, headache

GI: diarrhea

GU: reversible erectile dysfunction, gynecomastia


Drug-drug. Calcium channel blockers, carbamazepine, chloroquine, lidocaine, metformin, metronidazole, moricizine, pentoxifylline, phenytoin, propafenone, quinidine, quinine, some benzodiazepines, some beta-adrenergic blockers (chlordiazepoxide, diazepam, midazolam), sulfonylureas, tacrine, theophylline, triamterene, tricyclic antidepressants, valproic acid, warfarin: decreased metabolism of these drugs, possible toxicity

Drug-diagnostic tests. Creatinine, transaminases: increased levels

Parathyroid hormone: decreased level Skin tests using allergenic extracts: false-negative results (drug should be discontinued 24 hours before testing)

Drug-food. Caffeine-containing foods and beverages (such as coffee, chocolate): increased cimetidine blood level, increased risk of toxicity

Drug-herbs. Pennyroyal: change in formation rate of herb's toxic metabolite

Yerba maté: decreased yerba maté clearance, possible toxicity

Drug-behaviors. Alcohol use: increased blood alcohol level

Smoking: reversed cimetidine effects

Patient monitoring

• Monitor creatinine levels in patients with renal insufficiency or failure.

• Assess elderly or chronically ill patients for confusion (which usually resolves once drug therapy ends).

Patient teaching

• Inform patient with gastric ulcer that ulcer may take up to 2 months to heal. Advise him not to discontinue therapy, even if he feels better, without first consulting prescriber. Ulcer may recur if therapy ends too soon.

• Advise patient not to take over-the-counter cimetidine for more than 2 weeks continuously, except with prescriber's advice and supervision.

• As appropriate, review all other significant adverse reactions and interactions, especially those related to the drugs, tests, foods, herbs, and behaviors mentioned above.


A histamine analogue and antagonist used to treat peptic ulcer and hypersecretory conditions by blocking histamine H2 receptor sites, thus inhibiting gastric acid secretion.


(sĭ-mĕt′ĭ-dēn′, -dīn′)
A histamine receptor antagonist, C10H16N6S, that inhibits acid secretion in the stomach and is used to treat duodenal and gastric ulcers and gastroesophageal reflux disease.


Tagamet Clinical therapeutics An H2-receptor antagonist used to treat peptic ulcer disease Adverse reactions Diarrhea, headache, drowsiness, fatigue, muscle pain, constipation; rarely mental confusion, agranulocytosis, gynecomastia, impotence, allergic reactions, myalgias, tachycardia, arrhythmias, interstitial nephritis, mild ↑ in creatinine. See Histamine receptor antagonists.


A histamine analogue and antagonist used to treat peptic ulcer and hypersecretory conditions by blocking histamine H2 receptor sites, thus inhibiting gastric acid secretion.


A histamine H-2 receptor antagonist drug used to limit acid production in the stomach in cases of peptic ulcer. The drug is on the WHO official list. Brand names are Tagamet, Dyspamet, Galenamet, and Zita.


Histamine analogue and antagonist used to treat peptic ulcer and hypersecretory conditions.
References in periodicals archive ?
Through all advertising media, the messages had to be consistent, promoting the product's prescription drug heritage, the up to 12-hour acid suppression claim, and the differentiation of Zantac 75 from Tagamet HB or Pepcid AC.
Prior to the OTC conversion of Johnson & Johnson's Pepcid (to Pepcid AC) and SmithKline Beecham's Tagamet (to Tagamet HB), and the impending conversion of Glaxo's Zantac (currently under FDA review) - all H2 blockers, a revolutionary form of antacid medication - the category was worth about $800 million.
"So, in the case of Tagamet, we believe retailers actually make more profit on Tagamet HB [OTC] than they would on Tagamet Rx."
"We want to help people understand what Tagamet HB is and what it is used for," says Bradley.
Tums Mylanta Pepcid AC Pepcid Rolaids Maalox Tagamet HB Tagamet Zantac(*)
Zantac 75 joined Pepcid AC, the first O-T-C [H.sub.2] blocker introduced, and Tagamet HB in the race for dominance in the acid blocker category.
The two acid blockers that have already received Food and Drug Administration clearance, Pepcid and Tagamet HB, and have only been available since midsummer, rank No.
It's followed by Tagamet HB tablets in 32-count containers (12th) and Tagamet 64-count packages (19th).
Already, Johnson & Johnson/Merck Consumer Pharmaceuticals Co.'s Pepcid AC (famotidine) is on store shelves in O-T-C form, SmithKline Beecham PLC's Tagamet HB (cimetidine) is due to follow soon, and Glaxo Wellcome Inc.
Similar H2 blockers - Tagamet HB (cimetidine) from SmithKline Beecham PLC, Zantac (ranitidine HCl) from Glaxo Wellcome Inc.
Last month the company received FDA approval to take the product into the O-T-C arena as Tagamet HB. Like Pepcid AC it will be less potent than the prescription drug.