Class: Histamine H 2 antagonist
- Tablets 300 mg
- Tablets 400 mg
- Tablets 800 mg
- Liquid 300 mg (as hydrochloride) per 5 mL
- Injection 150 mg (as hydrochloride) per mL
Cimetidine in 0.9% Sodium Chloride
- Injection, premixed 6 mg (as hydrochloride) per mL
- Tablets 200 mg
Reversibly and competitively blocks histamine at H 2 receptors, particularly those in gastric parietal cells, leading to inhibition of gastric acid secretion.
Rapidly absorbed. T max is 45 to 90 min. 60% to 70% bioavailable.
13% to 25% protein bound. Vd is 0.8 to 1.2 L/kg. Crosses the placenta and is excreted in breast milk.
Following oral administration, cimetidine is extensively metabolized with the sulfoxide being the major metabolite.
The t ½ is about 2 h.Oral
48% is excreted unchanged in the urine.IV/IM
About 75% is excreted unchanged in the urine.
Special PopulationsRenal Function Impairment
Drug accumulation may occur in those with severe renal failure. Dosage adjustment may be necessary.
Indications and Usage
Management of duodenal ulcer; treatment of gastroesophageal reflux disease (GERD), including erosive esophagitis; therapy for benign gastric ulcer; treatment of pathologic hypersecretory conditions; prevention of upper GI bleeding.
Prevention of aspiration pneumonia and stress ulcers; herpes virus infection; chronic idiopathic urticaria; anaphylaxis (relieves dermatologic symptoms only); dyspepsia; used before anesthesia to prevent aspiration pneumonitis; treatment of hyperparathyroidism and control of secondary hyperparathyroidism in chronic hemodialysis patient; treatment of chronic viral warts in children.
Hypersensitivity to cimetidine or other H 2 antagonists.
Dosage and AdministrationDuodenal Ulcer (Active)
PO 800 mg at bedtime for 4 to 6 wk.Alternate regimens
PO 300 mg 4 times daily with meals and at bedtime or 400 mg twice daily.Maintenance Therapy
PO 400 mg at bedtime.Active Benign Gastric Ulcer
PO 800 mg at bedtime.GERD
PO 1600 mg daily in divided doses (800 mg or 400 mg) for 12 wk, although some patients may require chronic therapy.Pathologic Hypersecretory Conditions
PO 300 mg 4 times daily w/meals and at bedtime. If needed, 300 mg doses may be given more often (max, 2400 mg/day).Prevention of Upper GI Bleeding
Continuous IV infusion of 50 mg/h. For hospitalized patients with pathologic hypersecretory conditions or intractable ulcers, or patients unable to take PO medication.Usual dose
IM/IV 300 mg every 6 h to 8 h (max 2400 mg/day).
- Dilute IV dose (300 mg) in 0.9% normal saline, D5W, or other compatible solution to a total of 20 mL. Inject slowly over at least 5 min.
- For intermittent IV infusion, dilute 300 mg in at least 50 mL of compatible solution; infuse over at least 20 min (continuous IV infusion is usually preceded by a loading dose).
- Do not add drugs or additives to mixture. Stop other inline drugs while administering, and flush lines before and after administration.
- Product may be added to standard TPN solutions.
Store premixed products at room temperature. Discard any unused mixed solutions after 48 h. Store oral doseform between 15° to 30°C (59° to 86°F).
Drug InteractionsAntacids, anticholinergics, metoclopramide
May decrease absorption of cimetidine.Benzodiazepines, caffeine, calcium channel blockers, carbamazepine, chloroquine, labetalol, lidocaine, metoprolol, metronidazole, moricizine, pentoxifylline, phenytoin, propranolol, quinidine, quinine, sulfonylureas, theophyllines, triamterene, tricyclic antidepressants, warfarin
Cimetidine may reduce metabolism and increase serum concentration and pharmacologic/toxic effects of these drugs.Carmustine
Bone marrow toxicity may be enhanced.Cigarette smoking
Reversed cimetidine's effects on suppression of nocturnal gastric secretion.Ferrous salts, indomethacin, fluconazole, ketoconazole, tetracyclines
Cimetidine may decrease absorption of these drugs.Hydantoins
Hydantoin levels may increase.Narcotic analgesics
Toxic effects (eg, respiratory depression) may be increased.Procainamide
Levels of procainamide and its active metabolite may increase.Tocainide
Cimetidine may decrease the pharmacologic effects of tocainide.
Laboratory Test Interactions
None well documented.
Headache; somnolence; fatigue; dizziness; confusional states; hallucinations.
Exfoliative dermatitis or erythroderma; alopecia; rash; erythema multiforme; epidermal necrolysis.
Impotence; loss of libido.
Gynecomastia; hypersensitivity reactions; transient pain at injection site; reversible exacerbation of joint symptoms with pre-existing arthritis, including gouty arthritis.
Category B .
Excreted in breast milk.
Safety and efficacy not established.
May have reduced renal function; decreased Cl may occur.
Rare cases of anaphylaxis have occurred as well as rare episodes of hypersensitivity.
Decreased Cl may occur; reduced dosage may be needed.
Use caution; decreased Cl may occur.
Symptomatic relief with cimetidine does not preclude gastric malignancy.
Gynecomastia may occur, especially in patients treated for pathologic hypersecretory states.
Rapid IV administration
Has been followed by rare instances of cardiac arrhythmias and hypotension.
Reversible CNS effects
Mental confusion, agitation, psychosis, depression, anxiety, hallucinations, and disorientation have occurred, predominantly in severely ill patients. Advanced age and pre-existing liver or renal disease appear to be contributing factors.
- Counsel patients to stop smoking, since smoking reduces ulcer-healing efficacy of cimetidine.
- Instruct patients to keep appointments for laboratory testing and health care provider follow-up.
- Instruct patients to report to health care provider immediately any black tarry stools, coffee-ground emesis, abdominal pain or confusion.
- Counsel patients regarding need for lifestyle changes, stress reduction programs and dietary modifications (eg, avoid spicy foods and alcohol).
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