The oral LD50 for flavoxate HC1 in rats is 4273 mg/kg. The oral LD50 for flavoxate HC1 in mice is 1837 mg/kg. It is not known whether flavoxate HC1 is dialyzable.
Genurin® (flavoxate HC1) is contraindicated in patients who have any of the following obstructive conditions: pyloric or duodenal obstruction, obstructive intestinal lesions or ileus, achalasia, gastrointestinal hemorrhage and obstructive uropathies of the lower urinary tract.
The following adverse reactions have been observed, but there are not enough data to support an estimate of their frequency.
Gastrointestinal: Nausea, vomiting, dry mouth.
CNS: Vertigo, headache, mental confusion, especially in the elderly, drowsiness, nervousness.
Hematologic: Leukopenia (one case which was reversible upon discontinuation of the drug).
Cardiovascular: Tachycardia and palpitation.
Allergic: Urticaria and other dermatoses, eosinophilia and hyperpyrexia.
Ophthalmic: Increased ocular tension, blurred vision, disturbance in eye accommodation.
Renal: Dysuria.
Genurin® (flavoxate HC1) should be given cautiously in patients with suspected glaucoma.
PRECAUTIONS Carcinogenesis, Mutagenesis, Impairment of FertilityMutagenicity studies and long-term studies in animals to determine the carcinogenic potential of Genurin® (flavoxate HC1) have not been performed.
Pregnancy Teratogenic Effects-Pregnancy Category B.Reproduction studies have been performed in rats and rabbits at doses up to 34 times the human dose and revealed no evidence of impaired fertility or harm to the fetus due to flavoxate HC1. There are, however, no 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 MothersIt is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when Genurin® is administered to a nursing woman.
Pediatric UseSafety and effectiveness in children below the age of 12 years have not been established.
One or two 100 mg tablets 3 or 4 times a day. With improvement of symptoms, the dose may be reduced. This drug cannot be recommended for infants and children under 12 years of age because safety and efficacy have not been demonstrated in this age group.
