Cimetidine

Cimetidine tablets are indicated in: 1. Short-term treatment of active duodenal ulcer. Most patients heal within 4 weeks and there is rarely reason to use cimetidine tablets at full dosage for longer than 6 to 8 weeks (see DOSAGE AND ADMINISTRATION: Duodenal Ulcer ). Concomitant antacids should be given as needed for relief of pain. However, simultaneous administration of cimetidine tablets and antacids is not recommended, since antacids have been reported to interfere with the absorption of cimetidine. 2. Maintenance therapy for duodenal ulcer patients at reduced dosage after healing of active ulcer. …

• Duodenal Ulcer Active Duodenal Ulcer Clinical studies have indicated that suppression of nocturnal acid is the most important factor in duodenal ulcer healing (see CLINICAL PHARMACOLOGY: Antisecretory Activity: Acid Secretion )
• This is supported by recent clinical trials (see CLINICAL TRIALS: Duodenal Ulcer: Active Duodenal Ulcer )
• Therefore, there is no apparent rationale, except for familiarity with use, for treating with anything other than a once-daily at bedtime dosage regimen
• In a U.S. dose-ranging study of 400 mg at bedtime, 800 mg at bedtime and 1600 mg at bedtime, a continuous dose-response relationship for ulcer healing was demonstrated
• However, 800 mg at bedtime is the dose of choice for most patients, as it provides a high healing rate (the difference between 800 mg at bedtime and 1,600 mg at bedtime being small), maximal pain relief, a decreased potential for drug interactions (see PRECAUTIONS: Drug Interactions ) and maximal patient convenience
• Patients unhealed at 4 weeks, or those with persistent symptoms, have been shown to benefit from 2 to 4 weeks of continued therapy
• It has been shown that patients who both have an endoscopically demonstrated ulcer larger than 1.0 cm and are also heavy smokers (i.e., smoke 1 pack of cigarettes or more per day) are more difficult to heal
• There is some evidence which suggests that more rapid healing can be achieved in this subpopulation with 1,600 mg of cimetidine tablets at bedtime. …

Cimetidine tablets are contraindicated for patients known to have hypersensitivity to the product.

PRECAUTIONS General Rare instances of cardiac arrhythmias and hypotension have been reported following the rapid administration of cimetidine hydrochloride injection by intravenous bolus. Symptomatic response to treatment with cimetidine tablets do not preclude the presence of a gastric malignancy. There have been rare reports of transient healing of gastric ulcers despite subsequently documented malignancy. Reversible confusional states (see ADVERSE REACTIONS ) have been observed on occasion, predominantly, but not exclusively, in severely ill patients. Advancing age (50 or more years) and preexisting liver and/or renal disease appear to be contributing factors. …

Adverse effects reported in patients taking cimetidine tablets are described as follows by body system. Incidence figures of 1 in 100 and greater are generally derived from controlled clinical studies. Gastrointestinal Diarrhea (usually mild) has been reported in approximately 1 in 100 patients. CNS Headaches, ranging from mild to severe, have been reported in 3.5% of 924 patients taking 1,600 mg/day, 2.1% of 2,225 patients taking 800 mg/day and 2.3% of 1,897 patients taking placebo. Dizziness and somnolence (usually mild) have been reported in approximately 1 in 100 patients on either 1,600 mg/day or 800 mg/day. …

Studies in animals indicate that toxic doses are associated with respiratory failure and tachycardia that may be controlled by assisted respiration and the administration of a beta-blocker. Reported acute ingestions orally of up to 20 grams have been associated with transient adverse effects similar to those encountered in normal clinical experience. The usual measures to remove unabsorbed material from the gastrointestinal tract, clinical monitoring, and supportive therapy should be employed. …

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