DRUG INTERACTIONS
Drug Laboratory Test Interactions
When Benedict's or Fehling's solution or Clinitest® Reagent Tablets are used to test the urine of patients taking NegGram, a false-positive reaction for glucose may be obtained, due to the liberation of glucuronic acid from the metabolites excreted. However, a colorimetric test for glucose based on an enzyme reaction (e.g., with Clinistix® Reagent Strips or Tes-Tape®) does not give a false-positive reaction to the liberated glucuronic acid.
Incorrect values may be obtained for urinary 17-keto and ketogenic steroids in patients receiving NegGram, because of an interaction between the drug and the m -dinitrobenzene used in the usual assay method. In such cases, the Porter-Silber test for 17-hydroxycorticoids may be used.
Carcinogenesis, Mutagenesis, Impairment of Fertility
In lifetime studies in the rat given nalidixic acid in the diet, there was an increased incidence of preputial gland neoplasms in the treated males and clitoral gland neoplasms in the treated females. Studies in mice in which nalidixic acid was administered in the feed for two years, or was given in the feed for 76 weeks followed by no treatment for 9 weeks, gave equivocal evidence of carcinogenic activity.
Nalidixic acid was tested in the Ames bacterial mutagenicity test (maximum dose 33 mcg/plate) and the mouse lymphoma assay (L5178Y/TK; maximum dose 100 mcg/mL) with and without metabolic activation, and results were negative.
Pregnancy
Teratogenic Effects
Pregnancy Category C
NegGram has been shown to be teratogenic and embryocidal in rats when given in oral doses six times the human dose. NegGram also prolonged the duration of pregnancy especially at four times the clinical dose. There are no adequate and well-controlled studies in pregnant women. Since nalidixic acid, like other drugs in this class, causes arthropathy in immature animals, NegGram should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. (See WARNINGS and ANIMAL PHARMACOLOGY.)
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