DRUG INTERACTIONS
Carcinogenesis, Mutagenesis, Impairment of Fertility
Tegaserod was not carcinogenic in rats given oral dietary doses up to 180 mg/kg/day (approximately 93 to 111 times the human exposure at 6 mg b.i.d. based on plasma AUC0-24 hr) for 110 to 124 weeks.
In mice, dietary administration of tegaserod for 104 weeks produced mucosal hyperplasia and adenocarcinoma of small intestine at 600 mg/kg/day (approximately 83 to 110 times the human exposure at 6 mg b.i.d. based on plasma AUC0-24 hr). There was no evidence of carcinogenicity at a lower dose of 200 mg/kg/day (approximately 24 to 35 times the human exposure at 6 mg b.i.d. based on plasma AUC0-24 hr) or 60 mg/kg/day (approximately 3 to 4 times the human exposure at 6 mg b.i.d. based on plasma AUC0-24 hr).
Tegaserod was not genotoxic in the in vitro Chinese hamster lung fibroblast (CHL/V79) cell chromosomal aberration test, the in vitro Chinese hamster lung fibroblast (CHL/V79) cell forward mutation test, the in vitro rat hepatocyte unscheduled DNA synthesis (UDS) test or the in vivo mouse micronucleus test. The results of Ames test for mutagenicity were equivocal.
Tegaserod at oral doses up to 240 mg/kg/day (approximately 57 times the human exposure at 6 mg b.i.d. based on plasma AUC0-24 hr) in male rats and 150 mg/kg/day (approximately 42 times the human exposure at 6 mg b.i.d. based on plasma AUC0-24 hr) in female rats was found to have no effect on fertility and reproductive performance.
Pregnancy, Teratogenic Effects: Pregnancy Category B
Reproduction studies have been performed in rats at oral doses up to 100 mg/kg/day (approximately 15 times the human exposure at 6 mg b.i.d. based on plasma AUC0-24 hr) and rabbits at oral doses up to 120 mg/kg/day (approximately 51 times the human exposure at 6 mg b.i.d. based on plasma AUC0-24 hr) and have revealed no evidence of impaired fertility or harm to the fetus due to tegaserod. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.
Nursing Mothers
Tegaserod and its metabolites are excreted in the milk of lactating rats with a high milk to plasma ratio. It is not known whether tegaserod is excreted in human milk. Many drugs, which are excreted in human milk, have potential for serious adverse reactions in nursing infants. Based on the potential for tumorigenicity shown for tegaserod in the mouse carcinogenicity study, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Pediatric Use
Zelnorm has not been studied in pediatric patients.
Geriatric Use
IBS with Constipation
Of 4,035 patients in Phase 3 clinical studies of Zelnorm, 290 were at least 65 years of age, while 52 were at least 75 years old. No overall differences in safety were observed between these patients and younger patients with regard to adverse events.
No dose adjustment is necessary when administering Zelnorm to patients with IBS with constipation over 65 years old. (See CLINICAL PHARMACOLOGY.)
Chronic Idiopathic Constipation
Of 2,612 patients in Phase 3 clinical studies of Zelnorm, 331 were at least 65 years of age. Efficacy in patients 65 years of age or greater showed no significant difference between drug and placebo responses. Patients 65 years of age or greater who received Zelnorm experienced a higher incidence of diarrhea and discontinuations due to diarrhea than patients younger than 65.
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