Introduction

Nalidixic acid [l-ethyl-l,4-dihydro-7-methyl-4-oxo-1,8-naphthyridine-3-carbosylic acid, here abbreviated NAL] is a clinically important antibacterial drug more effective against gram-negative than gram-positive organisms. It is a monocarboxylic acid comprising 1,8-naphthyridin-4-one substituted by carboxylic acid, ethyl, and methyl groups at positions 3, 1, and 7, respectively.

NAL is a heat-stable weak organic acid with a molecular weight of 232.3 daltons. It is sparingly soluble in water but highly soluble in aqueous bases or polar organic solv!:lnts. Stock solutions are prepared by dissolving 10 mg/ml NAL in O.IN NaOH and adjusting the pH to 8.5.

Uses

NAL is very well tolerated in man and laboratory animals. The major clinical use is in treating urinary infections caused by Klebsiella and the indole-positive strains of Proteus. It is also used to treat uncomplicated urinary tract infections caused by gram-negative bacteria other than Pseudomonas spp.

Nalidixic acid has a bactericidal or bacteriostaic effect depending on the sensitivity of the microorganism and the concentration. It is effective with respect to Gram-negative microorganisms, such as colon bacillus, salmonella, shigella, proteus, and Fridlender’s bacillus. It is used for pyeolonephritis, cystitis, urethritis, prostatitis, and gastrointestinal tract infections. Synonyms of this drug are negram, nevigramon, uralgin, urogram, vintron, and many others.

Contraindications

Nalidixic acid should not be prescribed for children or adolescents younger than eighteen years of age due to the risk of cartilage damage and subsequent growth impairment. Efficacy and safety of nalidixic acid have not been established in pregnant and lactating women. Nalidixic acid is contraindicated in individuals with a history of hypersensitivity to any quinolone antibiotic. Nalidixic acid should not be used for patients with porphyria. Nalidixic acid should be avoided in patients with impaired hepatic function, renal insufficiency, or glucose-6-phosphate dehydrogenase deficiency. In light of its central stimulant effects, nalidixic acid should be used with caution in patients with a history of seizures. Those treated with nalidixic acid should avoid exposure to ultra-violet light.