Nalidixic Acid

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Chemical Structure / Formula of Nalidixic Acid

• Formula: C12H12N2O3

• Structure: 1,8-naphthyridine core with a carboxyl (-COOH) and ketone (-C=O) functional group.

Mechanism of Action

• Inhibits DNA gyrase (topoisomerase II) and topoisomerase IV, preventing bacterial DNA replication.

• Bactericidal effect due to DNA fragmentation and inhibition of supercoiling.

Uses

• First-generation quinolone used primarily for urinary tract infections (UTIs) caused by E. coli, Proteus, Klebsiella.

• Not used for systemic infections (poor penetration).

Side Effects

• GI upset (nausea, vomiting, diarrhea).

• CNS effects (dizziness, headache, confusion in elderly patients).

• Photosensitivity.

• Rare: hemolytic anemia in G6PD deficiency.

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