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Reflux is caused by weakness in the muscle at the junction of the esophagus with the stomach. Normally, this muscular valve, or sphincter, functions to keep food and stomach acid from moving upward from the stomach to the esophagus and larynx. This valve opens to allow food into the stomach and closes to keep the stomach's contents from coming back up. The backward movement of stomach contents (gastric contents) up into the esophagus is referred to as gastroesophageal reflux.
Additionally, any increase in abdominal pressure (such as obesity), which can push acid back from the stomach up the esophagus, or a patient with a hiatal hernia, will have an increased risk for reflux. When it causes symptoms, it is referred to as gastroesophageal reflux disease (or GERD). When the acid backs up into the voice box (larynx), the condition is referred to as reflux laryngitis.
Stomach acid can cause irritati...
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General1. Symptomatic response to nizatidine therapy does not preclude the presence of gastric malignancy.
2. Because nizatidine is excreted primarily by the kidney, dosage should be reduced in patients with moderate to severe renal insufficiency (see DOSAGE AND ADMINISTRATION).
3. Pharmacokinetic studies in patients with hepatorenal syndrome have not been done. Part of the dose of nizatidine is metabolized in the liver. In patients with normal renal function and uncomplicated hepatic dysfunction, the disposition of nizatidine is similar to that in normal subjects.
Laboratory TestsFalse-positive tests for urobilinogen with MultistixÃ? may occur during therapy with nizatidine.
Carcinogenesis, Mutagenesis, Impairment of FertilityA 2-year oral carcinogenicity study in rats with doses as high as 500 mg/kg/day (about 13 times the recommended human dose based on body surface area) showed no evidence of a carcinogenic effect. There was a dose-related increase in the density of enterochromaffin-like (ECL) cells in the gastric oxyntic mucosa. In a 2-year study in mice, there was no evidence of a carcinogenic effect in male mice; although hyperplastic nodules of the liver were increased in the high-dose males as compared with placebo. Female mice given the high dose of nizatidine (2,000 mg/kg/day, about 27 times the recommended human dose based on body surface area) showed marginally statistically significant increases in hepatic carcinoma and hepatic nodular hyperplasia with no numerical increase seen in any of the other dose groups. The rate of hepatic carcinoma in the high-dose animals was within the historical control limits seen for the strain of mice used. The female mice were given a dose larger than the maximum tolerated dose, as indicated by excessive (30%) weight decrement as compared with concurrent controls and evidence of mild liver injury (transaminase elevations). The occurrence of a marginal finding at high dose only in animals given an excessive and somewhat hepatotoxic dose, with no evidence of a carcinogenic effect in rats, male mice, and female mice (given up to 360 mg/kg/day, about 5 times the recommended human dose based on body surface area), and a negative mutagenicity battery are not considered evidence of a carcinogenic potential for nizatidine.
Nizatidine was not mutagenic in a battery of tests performed to evaluate its potential genetic toxicity, including bacterial mutation tests, unscheduled DNA synthesis, sister chromatid exchange, mouse lymphoma assay, chromosome aberration tests, and a micronucleus test.
In a 2-generation, perinatal and postnatal fertility study in rats, doses of nizatidine up to 650 mg/kg/day (about 17.5 times the recommended human dose based on body surface area) produced no adverse effects on the reproductive performance of parental animals or their progeny.
PregnancyTeratogenic EffectsPregnancy Category BOral reproduction studies in pregnant rats at doses up to 1500 mg/kg/day (about 40.5 times the recommended human dose based on body surface area) and in pregnant rabbits at doses up to 275 mg/kg/day (about 14.6 times the recommended human dose based on body surface area) have revealed no evidence of impaired fertility or harm to the fetus due to nizatidine. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.
Nursing MothersStudies conducted in lactating women have shown that 0.1% of the administered oral dose of nizatidine is secreted in human milk in proportion to plasma concentrations. Because of the growth depression in pups reared by lactating rats treated with nizatidine, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
Pediatric UseEffectiveness in pediatric patients <12 years of age has not been established. Use of nizatidine in pediatric patients from 12 to 18 years of age is supported by evidence from published pediatric literature, adequate and well-controlled published studies in adults, and by the following adequate and well-controlled studies in pediatric patients: (see DOSAGE AND ADMINISTRATION)
Clinical Trials (Pediatric). In randomized studies, nizatidine was administered to pediatric patients for up to eight weeks, using age appropriate formulations. A total of 230 pediatric patients from 2 to 18 years of age were administered nizatidine at a dose of either 2.5 mg/kg b.i.d, or 5.0 mg/kg b.i.d, (patients 12 years and under) or 150 mg b.i.d (12 to 18 years). Patients were required to have either symptomatic, clinically suspected or endoscopically diagnosed GERD with age-relevant symptoms. In patients 2 to 18 years of age, nizatidine was found generally safe and well-tolerated. In these studies in patients 12 years and older, nizatidine was found to reduce the severity and frequency of GERD symptoms, improve physical well-being, and reduce the frequency of supplemental antacid consumption. No efficacy in pediatric patients <12 years of age has been established. Clinical studies in patients 2 to 12 years of age with GERD, demonstrated no difference in either symptom improvements or healing rates between nizatidine and placebo or between different doses of nizatidine.
Geriatric UseOf the 955 patients in clinical studies who were treated with nizatidine, 337 (35.3%) were 65 and older. No overall differences in safety or effectiveness were observed between these and younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.
This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function (see DOSAGE AND ADMINISTRATION).
Last reviewed on RxList: 5/30/2006
This monograph has been modified to include the generic and brand name in many instances.
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