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Nalidixic Acid information from DrugsUpdate  

See Available Brands of Nalidixic Acid in India

P - Caution when used during pregnancy
L - Caution when used during lactation
LI - Lab *

Nalidixic acid (tradenames Neggram, Wintomylon and WIN-18320) is the first of the synthetic quinolone antibiotics.

Synthetic quinolone antibiotics were discovered as a byproduct of quinine manufacture in the 1960s.

Nalidixic acid is effective against both gram-positive and gram-negative bacteria. In lower concentrations, it acts in a bacteriostatic manner; that is, it inhibits growth and reproduction. In higher concentrations, it is bactericidal, meaning that it kills bacteria instead of merely inhibiting their growth.

It is especially used in treating urinary tract infections, caused, for example, by Escherichia coli, Proteus, Shigella, Enterobacter, and Klebsiella.. It is also a tool in studies as a regulation of bacterial division. It selectively and reversibly blocks DNA replication in susceptible bacteria. Nalidixic acid and related antibiotics inhibit a subunit of DNA gyrase and induce formation of relaxation complex analogue. It also inhibits the nicking dosing activity on the subunit of DNA gyrase that release the positive binding stress on on the supercoiled DNA.



Nalidixic acid is a 4-quinolone antibacterial. It interferes with the replication of bacterial DNA by inhibiting DNA gyrase activity. It acts against gram-negative bacteria including E. coli, Proteus, Klebsiella, Enterobacter, Salmonella and Shigella spp.


Rapidly and almost completely absorbed from the GI tract. (oral); peak plasma concentrations after 1-2 hr (oral).


Crosses the placenta; enters the breast milk. Protein-binding: 93% (nalidixic acid); 63% (hydroxynalidixic acid).


Partially converted in the liver to hydroxynalidixic acid.


Via urine (80-90% as inactive metabolites); faeces (4%); 1-2.5 hr (elimination half-life).

Nalidixic Acid Indications / Nalidixic Acid Uses

Information Not Available

Nalidixic Acid Adverse Reactions / Nalidixic Acid Side Effects

Nausea, vomiting, diarrhoea, abdominal pain; photosensitivity reactions, allergic rash, urticaria, pruritus; visual disturbances, headache, dizziness or vertigo, drowsiness, confusion, depression, excitement, hallucinations, toxic psychoses or convulsions (especially after large doses), intracranial hypertension (especially in infants and young children), metabolic acidosis; peripheral neuropathies, muscular weakness, myalgia; arthralgia, tendon damage; cholestatic jaundice, thrombocytopenia, leucopenia.

Potentially Fatal: Erythema multiforme and Stevens-Johnson syndrome; anaphylactoid reactions. Auto-immune haemolytic anaemia (particularly in elderly patients).



Monitor blood counts and renal and hepatic function tests periodically if treatment is continued for more than 2 weeks.


Symptoms: Toxic psychosis, convulsions, increased intracranial pressure, metabolic acidosis, vomiting, nausea, lethargy. Management: Increase fluid admin; supportive measures. Anticonvulsants may be used in severe cases.

Special Precautions

Hepatic or moderate renal impairment, severe cerebral arteriosclerosis, G6PD deficiency. Monitor blood counts, renal and hepatic function for treatment >2 wk. Children <18 yr. Elderly. Avoid exposure to sunlight or sunlamps. Pregnancy and lactation.

Other Drug Interactions

Absorption reduced by sucralfate, and divalent and trivalent cations e.g. aluminium, calcium, iron, magnesium, zinc. Excretion reduced and plasma concentrations increased with probenecid. Reduced effects with chloramphenicol, nitrofurantoin, tetracycline.

Potentially Fatal: Fatal haemorrhagic enterocolitis may occur when used with high-dose melphalan in children. Increased risk of nephrotoxicity with ciclosporin. May increase effects of oral anticoagulants e.g. warfarin.

Other Interactions

Information Not Available


Uncomplicated lower urinary tract infections
Adult: 1 g 4 times daily for 1-2 wk. Long-term therapy: Reduce daily dose to 2 g.
Child: >3 mth: 50 mg/kg daily in 4 equally divided doses. Long-term therapy: Reduce dose to 30 mg/kg daily. Prophylaxis: 15 mg/kg bid.
Renal impairment: Reduced doses should be considered.
Hepatic impairment: Reduced doses should be considered.

Adult: 1 g 4 times daily for 5 days.
Child: ≥3 mth: 15 mg/kg 4 times daily for 5 days.
Renal impairment: Reduced doses should be considered.
Hepatic impairment: Reduced doses should be considered.


Should be taken with food

List of Contraindications

Nalidixic Acid and Pregnancy

Caution when used during pregnancy.

Category C: Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.

Nalidixic Acid and Lactation

Caution when used during lactation

Nalidixic Acid and Children

Safety and efficacy not established in infants younger than 3 months of age.

Use with caution in patients younger than 18 yr of age; may affect cartilage and joints.

Nalidixic Acid and Geriatic

Use with caution; may have reduced renal function, which could increase risk of toxic reactions to drug. Consider monitoring renal function in elderly patients.

Nalidixic Acid and Other Contraindications

Hypersensitivity. History of convulsive disorders or porphyria. Infants <3 mth. Severe renal impairment.


Store at room temperature, up to 25°C (77°F).


Lab interference

Store at room temperature, up to 25°C (77°F).


Nalidixic Acid brands in India:

Diarlop SUSP Dix Gramoneg Nadix Acutab Negadix

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