Ornidazole CAS 16773-42-5

Details:

Ornidazole is a synthetic antimicrobial agent belonging to the nitroimidazole class, similar to metronidazole and tinidazole. It is primarily used to treat infections caused by anaerobic bacteria and protozoa. Below is a detailed overview:

Mechanism of Action:

Prodrug Activation: In anaerobic organisms, the nitro group of ornidazole is reduced, generating toxic metabolites that disrupt microbial DNA, leading to cell death.

Selective Toxicity: Effective against organisms with low redox potentials (e.g., anaerobes), sparing human cells.

Indications:

1. Protozoal Infections:

   • Amebiasis (intestinal and hepatic).

   • Giardiasis.

   • Trichomoniasis (genital infections).

2. Anaerobic Bacterial Infections:

   • Bacterial vaginosis.

   • Pelvic inflammatory disease.

   • Dental/oral infections.

   • Surgical prophylaxis (preventing post-operative anaerobic infections).

3. Off-label Uses: Helicobacter pylori eradication (in combination therapy).

Pharmacokinetics:

Half-life: ~12–14 hours (longer than metronidazole), allowing once/twice-daily dosing.

Metabolism: Hepatic, via CYP450 enzymes.

Excretion: Primarily renal (60–70%) and fecal.

Dosage Forms:

Oral tablets, intravenous infusion, and topical formulations (varies by country).

Dosing:

• Adults: Typical regimens include:

  • Trichomoniasis: 1.5 g single dose or 500 mg twice daily for 5 days.

  • Amebiasis: 1–2 g/day for 3–5 days.

• Pediatrics: Weight-based dosing (e.g., 25–40 mg/kg/day).

Side Effects:

Common: Nausea, headache, dizziness, dry mouth, metallic taste.                                                                                                                                Rare but Serious:

Peripheral neuropathy (with prolonged use).                                                                                                                                                                Seizures, encephalopathy.                                                                                                                                                                                              Allergic reactions (rash, Stevens-Johnson syndrome).                                                                                                                                          Disulfiram-like reaction (avoid alcohol during treatment).

Contraindications:

Hypersensitivity to nitroimidazoles.

First trimester of pregnancy (caution advised; Category B/C depending on region).

Severe hepatic impairment.

Drug Interactions:

Alcohol: Causes disulfiram-like reaction (flushing, vomiting).

Warfarin: Potentiates anticoagulant effect (monitor INR).

CYP450 Inducers/Inhibitors: May alter ornidazole levels.

Advantages Over Metronidazole:

Longer half-life for less frequent dosing.

Potentially better tolerability (reduced GI side effects).

Brand Names:

Tiberal, Ornida, Ladoran, and others (varies globally).

Resistance:

Cross-resistance with other nitroimidazoles (e.g., metronidazole) is possible.

Special Populations:

Pregnancy: Use cautiously; avoid in first trimester unless benefits outweigh risks.

Lactation: Excreted in breast milk; consult healthcare provider.

Hepatic/Renal Impairment: Dose adjustment may be needed.

Storage:

Room temperature, protected from light/moisture.

Ornidazole is a valuable alternative in settings where compliance or metronidazole resistance/tolerability is a concern. Always consult local guidelines for specific recommendations.