Drug information of Nalidixic acid

Nalidixic acid

Drug group:

Treating urinary tract infections caused by certain bacteria. Nalidixic acid is an antibacterial. It works by killing sensitive bacteria in the urinary tract by stopping the production of essential proteins needed by the bacteria to survive.

Mechanism of effect

Evidence exists for Nalidixic acid that its active metabolite, hydroxynalidixic acid, binds strongly, but reversibly, to DNA, interfering with synthesis of RNA and, consequently, with protein synthesis.


Nalidixic acid is a quinolone antibacterial agent for oral administration. Nalidixic acid has marked antibacterial activity against gram-negative bacteria including Enterobacterspecies, Escherichia coli, Morganella Morganii;
Proteus Mirabilis, Proteus vulgaris, andProvidencia rettgeri. Pseudomonas species are generally resistant to the drug


Following oral administration, of nalidixic acid is rapidly absorbed from the gastrointestinal tract, partially metabolized in the liver, and rapidly excreted through the kidneys.
Unchanged nalidixic acid appears in the urine along with an active metabolite, hydroxynalidixic acid, which has antibacterial activity similar to that of nalidixic acid.


The recommended dosage for initial therapy in adults is 1 g administered four times daily for one or two weeks (total daily dose, 4 g).
For prolonged therapy, the total daily dose may be reduced to 2 g after the initial treatment period. Underdosage during initial
treatment may predispose to emergence of bacterial resistance. Pediatric Patients Until further experience is gained,nalidixic
should not be administered to infants younger than thre months. Dosage in pediatric patients 12 years of age and under should be calculated on the basis of body weight.
The recommended total daily dosage for initial therapy is 25 mg/lb/day (55 mg/kg/day), administered in four equally divided doses. For prolonged therapy, the total daily dose may be reduced to 15 mg/lb/day (33 mg/kg/day). nalidixic acid Caplets of 250 mg may be used


1- Central Nervous System (CNS) effects including convulsions, increased intracranial pressure, and toxic psychosis have been reported with nalidixic acid therapy.
2- Serious and occasionally fatal hypersensitivity (anaphylactoid) reactions, some following the first dose, have been reported in patients receiving quinolone therapy.

Points of recommendation

1- Blood counts and renal and liver function tests should be performed periodically if treatment is continued for more than two weeks.
2- Moderate to severe phototoxicity reactions have been observed in patients who are exposed to direct sunlight while receiving Nalidixic acid or other members of this drug class. Excessive sunlight should be avoided. Therapy should be discontinued if phototoxicity occurs.
3- Caution should be observed in patients with glucose-6-phosphate dehydrogenase deficiency.
4- Patients should be advised nalidixic acid may be taken with or without meals. Patients should be advised to drink fluids liberally and not take antacids.

Pregnancy level



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