Nalid300 mg/5 ml

Nalid is a first-generation quinolone antibacterial indicated for the treatment of urinary tract infections (UTIs) caused by susceptible strains of gram-negative organisms.

Established/Approved Use

• Uncomplicated urinary tract infections (cystitis, pyelonephritis) caused by susceptible gram-negative bacteria including Escherichia coli, Proteus species, Klebsiella species, and Enterobacter species.

Notes on Use

Nalid is an older, narrow-spectrum quinolone that has largely been superseded by newer fluoroquinolones in many countries due to a higher rate of resistance development and a narrower spectrum of activity. It is not effective against Pseudomonas aeruginosa or most gram-positive organisms and should not be used for systemic infections outside the urinary tract. Use should be guided by local susceptibility patterns and, where possible, urine culture and sensitivity testing.

Each tablet/capsule of Nalidixic Acid typically contains Nalidixic Acid 500 mg as the active ingredient. Oral suspension formulations typically contain Nalidixic Acid 250 mg per 5 mL. Strengths and formulations may vary by manufacturer; refer to the specific product label for exact composition and excipients.

Nalid is a synthetic, first-generation quinolone antibacterial agent, structurally related to (but distinct from) the later fluoroquinolone class of antibiotics. It was one of the earliest quinolones developed and is used mainly for treating uncomplicated urinary tract infections caused by susceptible gram-negative bacteria.

Nalid works by inhibiting bacterial DNA replication, leading to bacterial cell death. It is available in oral tablet and oral suspension forms.

Nalid belongs to the quinolone class of antibacterial agents (first-generation quinolone/non-fluorinated quinolone), distinct from but related to the later fluoroquinolone antibiotics.

Mechanism of Action

Nalidixic Acid acts by inhibiting bacterial DNA gyrase (topoisomerase II), an enzyme essential for bacterial DNA replication, transcription, and repair. This inhibition prevents supercoiling and unwinding of bacterial DNA required for replication, resulting in bactericidal activity against susceptible gram-negative organisms.

Pharmacokinetics

• Absorption: Rapidly and almost completely absorbed from the gastrointestinal tract after oral administration.
• Distribution: Widely distributed in body tissues and fluids; achieves high concentrations in urine.
• Metabolism: Partly metabolized in the liver to an active metabolite (hydroxynalidixic acid) and inactive metabolites.
• Elimination half-life: Approximately 1.1 to 2.5 hours in patients with normal renal function; may be prolonged to up to 21 hours in patients with significant renal impairment.
• Excretion: Primarily excreted in the urine, largely as metabolites, within about 24 hours.

Nalid is administered orally, with or without food. Doses should be spaced evenly through the day (every 6 hours) to maintain effective drug levels. Antacids or mineral supplements should not be taken within 2 hours of a dose. Complete the full prescribed course of therapy.

Clinically Significant Interactions

• Antacids and multivalent cations (aluminum, magnesium, calcium, iron, zinc): Reduce gastrointestinal absorption of Nalid, lowering its effectiveness. Separate dosing by at least 2 hours.
• Warfarin and other oral anticoagulants: Nalid may potentiate the anticoagulant effect, increasing bleeding risk. Monitor INR/prothrombin time closely if co-administered.
• Nitrofurantoin: May have an antagonistic effect on the antibacterial activity of Nalid; concurrent use is generally avoided.
• Other drugs that lower seizure threshold (e.g., theophylline, certain psychotropics): Additive risk of central nervous system stimulation and seizures when combined with Nalid.
• Probenecid: May increase serum concentration of Nalid by reducing renal excretion.
• Melphalan: Case reports of severe, sometimes fatal, hematologic toxicity and gastrointestinal reactions with concurrent use; avoid combination.

Common

• Gastrointestinal upset (nausea, vomiting, diarrhea, abdominal discomfort)
• Headache, dizziness, drowsiness, weakness
• Photosensitivity (skin reaction to sunlight/UV light)

Less Common

• Visual disturbances (blurred vision, altered color perception, diplopia)
• Allergic/hypersensitivity skin reactions (rash, pruritus)
• Arthralgia, myalgia

Rare but Serious

• Seizures/convulsions, especially in patients with predisposing CNS conditions (see Contraindications)
• Hemolytic anemia in patients with G6PD deficiency (see Contraindications)
• Hepatotoxicity (jaundice, elevated liver enzymes)
• Increased intracranial pressure (pseudotumor cerebri), particularly in children
• Severe hypersensitivity reactions including anaphylaxis
• Clostridioides difficile-associated diarrhea/colitis

Patients should seek prompt medical attention for severe rash, difficulty breathing, seizures, severe diarrhea, or signs of liver problems (yellowing of skin/eyes, dark urine).

Pregnancy: Nalid should generally be avoided during pregnancy. Animal studies with quinolone antibacterials, including Nalid, have shown effects on developing cartilage (arthropathy), raising theoretical concern for the developing fetus. Nalid should be used in pregnancy only if clearly needed and the potential benefit justifies the potential risk to the fetus; consult a physician before use in pregnancy.

Lactation: Nalid is excreted in breast milk. Hemolytic anemia has been reported in nursing infants of mothers taking Nalid, particularly in infants with G6PD deficiency. Breastfeeding is generally not recommended during treatment with Nalid; consult a physician to weigh risks and benefits and consider alternative antibacterials.

Central Nervous System Effects

Nalid may lower the seizure threshold and has been associated with convulsions, particularly in patients with a history of seizure disorders, cerebral arteriosclerosis, or other conditions predisposing to seizures. Use with caution in such patients (see Contraindications).

Photosensitivity

Nalid can cause photosensitivity reactions. Patients should avoid excessive sunlight/UV exposure and use sun protection during treatment.

G6PD Deficiency

Hemolysis may occur in patients with G6PD deficiency (see Contraindications).

Increased Intracranial Pressure

Bulging fontanelles have been reported in infants and pseudotumor cerebri (benign intracranial hypertension) in both infants and adults; symptoms typically resolve after discontinuation.

Hepatic and Renal Function

Use with caution in patients with hepatic or renal impairment; dose adjustment or closer monitoring may be needed, as elimination half-life is significantly prolonged in renal impairment.

Antibiotic Stewardship

Take exactly as prescribed by your physician; do not stop, extend, skip doses, or share this medicine with others without medical advice. Inappropriate use of antibacterials, including Nalid, can promote the development of resistant bacteria.

Symptoms of Nalid overdose may include nausea, vomiting, drowsiness, confusion, toxic psychosis, seizures/convulsions, and increased intracranial pressure. There is no specific antidote for Nalid overdose. If overdose is suspected, seek immediate medical attention or contact a poison control center. Management is supportive and symptomatic; the stomach may be emptied by induced vomiting or gastric lavage if presenting soon after ingestion, and standard supportive care (fluid therapy, monitoring, seizure management) should be provided under medical supervision. Do not attempt to manage a suspected overdose at home without medical guidance.

Store at room temperature (below 30°C), protected from light and moisture. Keep out of reach of children.

Pediatric Use

Nalid is not recommended for infants under 3 months of age (see Contraindications). In older infants and children, quinolone antibacterials including Nalid have been associated with arthropathy (cartilage damage) in juvenile animal studies; use in children should be limited to situations where the potential benefit outweighs this theoretical risk, and only under medical supervision. Weight-based dosing should be used (see Dosage and Administration).

Elderly

Elderly patients may be more susceptible to central nervous system effects and should be monitored closely. Age-related decline in renal function may require dose adjustment.

Renal Impairment

Elimination is significantly prolonged in renal impairment (half-life up to ~21 hours). Dose reduction or extended dosing intervals, and close monitoring, are recommended in patients with significant renal impairment.

Hepatic Impairment

Use with caution; monitor liver function, as rare hepatotoxicity has been reported.

G6PD Deficiency

Contraindicated due to risk of hemolysis (see Contraindications).

For acute uncomplicated urinary tract infection, Nalid is typically given for 1 to 2 weeks. If therapy needs to be continued beyond this period (e.g., for chronic or recurrent infection), the dose is usually reduced for the maintenance phase. The exact duration should be determined by the prescribing physician based on clinical response and, where available, urine culture results. The full course should always be completed as directed even if symptoms improve earlier.

Quinolone antibacterial (first-generation/non-fluorinated quinolone)

Nalidixic Acid inhibits bacterial DNA gyrase (topoisomerase II), blocking bacterial DNA replication and transcription, which results in bactericidal activity against susceptible gram-negative bacteria.

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Nalid may be used in children over 3 months of age for treatment of susceptible urinary tract infections, at a weight-based dose of approximately 13.75 mg/kg every 6 hours. Use in infants under 3 months of age is contraindicated, as safety and efficacy have not been established in this age group. Because quinolone antibacterials have been associated with cartilage/joint effects in juvenile animal studies, use in children should be reserved for situations where no suitable alternative exists and the expected benefit outweighs potential risk, under close medical supervision.