Usage
Ornidazole is prescribed for infections caused by anaerobic bacteria and certain parasites. These include:
- Bacterial vaginosis: A common vaginal infection characterized by an overgrowth of anaerobic bacteria.
- Trichomoniasis: A sexually transmitted infection caused by the parasite Trichomonas vaginalis.
- Amoebiasis: An infection caused by the parasite Entamoeba histolytica, affecting the intestines (amoebic dysentery) or other organs (e.g., liver abscess).
- Giardiasis: An intestinal infection caused by the parasite Giardia lamblia.
- Anaerobic bacterial infections: Including septicemia, meningitis, peritonitis, postoperative wound infections, and certain gynecological infections.
- Surgical prophylaxis: To prevent anaerobic bacterial infections, especially in colon and gynecological surgeries.
Pharmacological classification: Antibiotic, Antiparasitic.
Mechanism of action: Ornidazole is a 5-nitroimidazole derivative. It works by disrupting DNA synthesis and causing DNA strand breakage in anaerobic microorganisms and susceptible parasites, ultimately leading to cell death.
Alternate Names
The generic name is Ornidazole. It is marketed internationally under various brand names.
How It Works
Pharmacodynamics: Ornidazole exhibits activity against anaerobic bacteria and specific parasites. It achieves high concentrations in various tissues and fluids, including cerebrospinal fluid, facilitating its effectiveness against infections in these sites.
Pharmacokinetics:
- Absorption: Ornidazole is rapidly absorbed after oral administration, reaching peak plasma concentration within approximately 3 hours.
- Distribution: It distributes widely into body tissues and fluids.
- Metabolism: It is metabolized in the liver.
- Elimination: Primarily excreted in the urine, with a small amount eliminated unchanged. The elimination half-life is about 13 hours.
Mode of action: Inside the microbial cell, ornidazole’s nitro group is reduced to form cytotoxic metabolites. These metabolites form adducts with DNA, leading to DNA damage, inhibition of DNA synthesis, and ultimately cell death.
Receptor binding, enzyme inhibition, or neurotransmitter modulation: Ornidazole’s primary mechanism is through direct DNA damage; it doesn’t primarily act through receptor binding, enzyme inhibition, or neurotransmitter modulation.
Elimination pathways: Ornidazole is metabolized in the liver and excreted mainly in the urine.
Dosage
Standard Dosage
Adults:
- Amoebiasis: 500 mg twice daily for 5-10 days.
- Amoebic dysentery: 1500 mg once daily for 3 days or 1000 mg twice daily for 3 days (for patients >60 kg).
- Trichomoniasis:
- Acute: 1500 mg as a single dose.
- Chronic: 500 mg twice daily for 5 days.
- Giardiasis: 1500 mg once daily for 1-2 days.
- Bacterial Vaginosis: 500 mg twice daily for 5 days.
- Anaerobic infections: 500 mg twice daily for 5–10 days.
Children:
- Amoebiasis: 25 mg/kg (up to a maximum of 1500 mg) once daily for 5-10 days.
- Amoebic dysentery: 40 mg/kg (up to a maximum of 1500 mg) once daily for 3 days.
- Trichomoniasis: 25 mg/kg as a single dose.
- Giardiasis: 40 mg/kg (up to a maximum of 1500 mg) once daily for 1-2 days.
Special Cases:
- Elderly Patients: Dose adjustment may be required based on renal function.
- Patients with Renal Impairment: No dose adjustment is generally necessary. Hemodialysis patients may need an additional dose after each session.
- Patients with Hepatic Dysfunction: Double the dosing interval in severe hepatic impairment.
- Patients with Comorbid Conditions: Careful monitoring is advised, especially in patients with central nervous system diseases (e.g., epilepsy, multiple sclerosis).
Clinical Use Cases
Dosing in specific clinical scenarios follows the standard recommendations for the respective infection being treated.
- Intubation, Surgical Procedures, Mechanical Ventilation, ICU Use, Emergency Situations: Dosage should be individualized based on the specific infection being targeted and the patient’s condition. Surgical prophylaxis involves 1500 mg 12 hours before surgery followed by 500 mg every 12 hours for 3-5 days postoperatively.
Dosage Adjustments
Dose adjustment may be required in patients with renal or hepatic impairment. Consult specific guidelines for detailed dosage modification strategies.
Side Effects
Common Side Effects:
Nausea, vomiting, diarrhea, epigastric discomfort, dry mouth, metallic taste, headache, dizziness, fatigue.
Rare but Serious Side Effects:
Peripheral neuropathy (numbness, tingling, pain in hands and feet), seizures, severe skin reactions, leukopenia, jaundice, abnormal liver function tests.
Long-Term Effects:
Peripheral neuropathy can be a persistent issue with long-term use.
Adverse Drug Reactions (ADR):
Severe skin reactions (e.g., Stevens-Johnson syndrome), seizures, leukopenia, jaundice, and hepatotoxicity require immediate medical intervention.
Contraindications
Hypersensitivity to ornidazole or other nitroimidazole derivatives, first trimester of pregnancy.
Drug Interactions
Ornidazole can potentiate the effects of warfarin (blood thinner) and vecuronium bromide (muscle relaxant). Alcohol should be avoided during ornidazole treatment due to a potential disulfiram-like reaction (flushing, tachycardia, nausea, vomiting).
Pregnancy and Breastfeeding
Ornidazole should be avoided in the first trimester of pregnancy. Its use during later stages of pregnancy or breastfeeding should be considered only if the potential benefit outweighs the risk to the fetus or infant.
Drug Profile Summary
- Mechanism of Action: Disrupts DNA synthesis in anaerobic microorganisms and susceptible parasites.
- Side Effects: Nausea, vomiting, diarrhea, headache, dizziness, metallic taste; rarely, peripheral neuropathy, seizures.
- Contraindications: Hypersensitivity to nitroimidazoles, first trimester of pregnancy.
- Drug Interactions: Warfarin, vecuronium bromide, alcohol.
- Pregnancy & Breastfeeding: Avoid in the first trimester; use with caution later in pregnancy or during breastfeeding.
- Dosage: Refer to detailed dosage guidelines above.
- Monitoring Parameters: Liver function tests, complete blood count (if prolonged therapy).
Popular Combinations
Ornidazole is sometimes used in combination with ofloxacin for the treatment of mixed infections.
Precautions
- General Precautions: Assess for hypersensitivity and evaluate liver and kidney function.
- Specific Populations: Consult guidelines for use in pregnant or breastfeeding women, children, and the elderly.
- Lifestyle Considerations: Avoid alcohol during treatment. Advise patients about potential dizziness and its impact on driving or operating machinery.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Ornidazole?
A: Refer to the detailed dosage section above for specific recommendations based on the infection and patient population.
Q2: What are the common side effects of Ornidazole?
A: Common side effects include nausea, vomiting, diarrhea, headache, dizziness, and metallic taste.
Q3: What are the serious side effects of Ornidazole?
A: Seizures and peripheral neuropathy are rare but serious side effects that require medical attention.
Q4: Can Ornidazole be used during pregnancy?
A: Ornidazole is contraindicated in the first trimester. Its use during the second and third trimesters should be carefully considered, weighing the benefits against potential risks to the fetus.
Q5: Can Ornidazole be used during breastfeeding?
A: Limited data is available regarding Ornidazole use during breastfeeding. Its use should be carefully evaluated, considering the potential benefits for the mother and the potential risks for the infant.
Q6: What are the contraindications for Ornidazole?
A: Contraindications include hypersensitivity to ornidazole or other nitroimidazoles and the first trimester of pregnancy.
Q7: What drugs interact with Ornidazole?
A: Ornidazole can interact with anticoagulants (e.g., warfarin), muscle relaxants (e.g., vecuronium bromide), and alcohol.
Q8: How does Ornidazole work?
A: Ornidazole disrupts DNA synthesis in anaerobic microorganisms and susceptible parasites, ultimately leading to cell death.
Q9: What infections is Ornidazole used to treat?
A: Ornidazole is effective against infections caused by anaerobic bacteria, Trichomonas vaginalis, Entamoeba histolytica, and Giardia lamblia. It’s also used for surgical prophylaxis.
This information is current as of February 16, 2025, and is intended for qualified medical professionals. Always consult up-to-date guidelines and local regulations for the most accurate information.
