Usage
Metronidazole + Norfloxacin is a fixed-dose combination antibiotic indicated for treating bacterial and parasitic infections, particularly those affecting the gastrointestinal and genitourinary tracts. Its primary uses include:
- Bacterial diarrhea and dysentery
- Intestinal amebiasis
- Giardiasis
- Bacterial vaginosis
- Anaerobic bacterial infections
- Urinary tract infections
Pharmacological Classification:
- Antibiotic (specifically, a combination of a nitroimidazole antibiotic and a fluoroquinolone antibiotic)
Mechanism of Action:
Metronidazole disrupts DNA synthesis and integrity in susceptible anaerobic bacteria and protozoa, leading to cell death. Norfloxacin inhibits bacterial DNA gyrase and topoisomerase IV, enzymes essential for bacterial DNA replication and repair, resulting in bacterial cell death. The combination provides broad-spectrum coverage against a wide range of pathogens.
Alternate Names
There isn’t a universally recognized international nonproprietary name (INN) for this specific combination. It’s primarily identified by its constituent drugs, metronidazole, and norfloxacin.
Brand Names:
Several brand names exist depending on the region and manufacturer. A few examples include Nor Metrogyl, Embiotic and Metroflox.
How It Works
Pharmacodynamics:
- Metronidazole exhibits bactericidal and antiprotozoal activity against anaerobic bacteria and certain parasites.
- Norfloxacin is bactericidal against a range of gram-negative and some gram-positive bacteria.
Pharmacokinetics:
- Absorption: Both drugs are well-absorbed orally. Food may slightly delay metronidazole absorption, while dairy products and antacids can reduce norfloxacin absorption.
- Metabolism: Metronidazole is metabolized in the liver. Norfloxacin is partially metabolized.
- Elimination: Metronidazole is primarily excreted in the urine. Norfloxacin is excreted in both urine and feces.
Mode of Action:
- Metronidazole is reduced intracellularly by anaerobic organisms, forming cytotoxic metabolites that damage DNA.
- Norfloxacin inhibits bacterial DNA gyrase and topoisomerase IV, blocking DNA replication and transcription.
Receptor Binding, Enzyme Inhibition:
- Metronidazole: Interacts with microbial DNA.
- Norfloxacin: Inhibits bacterial DNA gyrase and topoisomerase IV.
Elimination Pathways:
- Metronidazole: Primarily renal excretion.
- Norfloxacin: Renal and hepatic excretion.
Dosage
The dosage and duration of treatment are dependent upon the specific infection, patient factors, and the susceptibility of the causative organisms. Always consult with a qualified medical professional for appropriate dosing.
Standard Dosage
Adults:
Typically, one tablet of Metronidazole + Norfloxacin (containing, for example, 400 mg Norfloxacin and 500 mg Metronidazole or other appropriate dosage) is taken twice daily for 5-10 days, depending on the infection being treated.
Children:
Use in children and adolescents below 18 years of age is generally not recommended. The safety and efficacy in this population have not been fully established. If considered necessary, dosage adjustments based on weight should be carefully calculated and monitored by a physician.
Special Cases:
- Elderly Patients: Dosage adjustments may be necessary based on renal function. Monitor carefully for adverse effects.
- Patients with Renal Impairment: Dose reduction is required in patients with creatinine clearance less than 30 ml/min.
- Patients with Hepatic Dysfunction: Use with caution and monitor liver function.
- Patients with Comorbid Conditions: Caution is advised in patients with CNS disorders (seizures, peripheral neuropathy) and those with a history of QT prolongation.
Clinical Use Cases
Specific dosage guidelines for specialized clinical settings (intubation, surgical procedures, ICU use) are not explicitly defined for this fixed combination and should be determined based on the infection being treated and patient-specific factors. Individual components might be utilized according to established guidelines.
Dosage Adjustments:
Dose modifications are necessary for patients with renal impairment, hepatic dysfunction, or other relevant conditions. Individual components may require specific adjustments.
Side Effects
Common Side Effects:
- Nausea
- Vomiting
- Diarrhea
- Abdominal pain
- Headache
- Dizziness
- Metallic taste in the mouth
Rare but Serious Side Effects:
- Seizures
- Peripheral neuropathy
- Stevens-Johnson syndrome
- Toxic epidermal necrolysis
- Pseudomembranous colitis
- Tendon rupture (especially in patients over 60, those using corticosteroids, or transplant recipients)
Long-Term Effects:
Chronic use can potentially lead to peripheral neuropathy, tendon damage, and Clostridium difficile - associated disease.
Adverse Drug Reactions (ADR):
Serious ADRs such as severe hypersensitivity reactions (anaphylaxis, angioedema), QT prolongation, and C. difficile colitis require immediate medical intervention.
Contraindications
- Hypersensitivity to metronidazole, norfloxacin, or other fluoroquinolones.
- History of tendon disorders related to fluoroquinolone use.
- Patients with epilepsy or other CNS disorders with increased seizure risk.
- Pregnancy (especially first trimester) and breastfeeding.
- Children and adolescents below 18 years of age (generally).
Drug Interactions
- Anticoagulants (e.g., warfarin): Norfloxacin can potentiate the anticoagulant effects, requiring close monitoring of INR.
- QT Prolonging Drugs (e.g., amiodarone, sotalol): Concomitant use can increase the risk of QT prolongation and torsades de pointes.
- Antacids, Multivitamins with Minerals: These can decrease norfloxacin absorption and should be taken at least 2 hours before or 4-6 hours after Norfloxacin.
- Oral Hypoglycemics (e.g., glibenclamide): Fluoroquinolones can cause hypoglycemia. Close blood glucose monitoring is required.
- Disulfiram: Avoid concurrent use of metronidazole and disulfiram due to potential for disulfiram-like reaction.
- Alcohol: Concomitant use of metronidazole and alcohol should be avoided due to the risk of a disulfiram-like reaction (nausea, vomiting, flushing, headache).
Pregnancy and Breastfeeding
Metronidazole + Norfloxacin is contraindicated during pregnancy, especially in the first trimester, due to the risk of fetal harm. Norfloxacin is classified as Pregnancy Category C (FDA). Both drugs can be excreted in breast milk, posing potential risks to the infant. Breastfeeding should be avoided while taking this medication. Safer alternatives should be considered.
Drug Profile Summary
- Mechanism of Action: Metronidazole: Disrupts microbial DNA. Norfloxacin: Inhibits bacterial DNA gyrase and topoisomerase IV.
- Side Effects: Nausea, vomiting, diarrhea, headache, dizziness, metallic taste; rarely seizures, peripheral neuropathy, tendon rupture.
- Contraindications: Hypersensitivity, tendon disorders related to fluoroquinolone use, epilepsy, pregnancy, breastfeeding, children (generally).
- Drug Interactions: Anticoagulants, QT prolonging agents, antacids, oral hypoglycemics, disulfiram, alcohol.
- Pregnancy & Breastfeeding: Contraindicated.
- Dosage: Varies based on indication and patient factors; typically, one tablet twice daily for 5-10 days in adults.
- Monitoring Parameters: Renal function, liver function (if pre-existing hepatic dysfunction), INR (if on warfarin), blood glucose (if on oral hypoglycemics), and signs of hypersensitivity reactions, peripheral neuropathy, or tendonitis.
Popular Combinations
This section is not applicable as Metronidazole + Norfloxacin itself is a fixed-dose combination. Combining it further with other drugs would only be done in specific situations under strict medical supervision and is not a “popular” scenario.
Precautions
- General Precautions: Thorough patient history, including drug allergies, hepatic/renal function, and CNS disorders, is essential before initiating treatment.
- Specific Populations:
- Pregnant Women: Contraindicated.
- Breastfeeding Mothers: Contraindicated.
- Children & Elderly: Use with caution in children (generally avoided). Dosage adjustment may be necessary in the elderly.
- Lifestyle Considerations: Avoid alcohol during and shortly after treatment with metronidazole. Advise patients to avoid driving or operating machinery if they experience dizziness or lightheadedness.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Metronidazole + Norfloxacin?
A: The dosage varies depending on the infection and patient-specific factors. Typically, one tablet (containing, for example, 400 mg Norfloxacin and 500 mg Metronidazole, or other appropriate strengths as prescribed) twice daily for 5-10 days in adults. Consult with a medical professional for individualized dosing.
Q2: What are the common side effects?
A: Common side effects include nausea, vomiting, diarrhea, headache, dizziness, and a metallic taste in the mouth.
Q3: Is Metronidazole + Norfloxacin safe during pregnancy?
A: No. Metronidazole + Norfloxacin is contraindicated during pregnancy, especially in the first trimester, due to potential fetal harm.
Q4: Can I breastfeed while taking Metronidazole + Norfloxacin?
A: No. Both metronidazole and norfloxacin are excreted in breast milk and can pose risks to the infant. Breastfeeding should be avoided while taking this medication.
Q5: What should I do if I miss a dose?
A: If you miss a dose, take it as soon as you remember. However, if it is close to the time for your next dose, skip the missed dose and continue with your regular schedule. Do not double the dose to catch up.
Q6: Can I drink alcohol while taking Metronidazole + Norfloxacin?
A: No. Alcohol should be avoided during and for at least 24 hours after completing metronidazole treatment due to the risk of a disulfiram-like reaction.
Q7: What are the serious side effects I should watch out for?
A: Rare but serious side effects can include seizures, peripheral neuropathy, severe allergic reactions, tendon rupture, and C. difficile - associated diarrhea. Seek immediate medical attention if these occur.
Q8: Are there any drug interactions I should be aware of?
A: Yes. Metronidazole + Norfloxacin can interact with several medications, including anticoagulants, QT prolonging drugs, antacids, oral hypoglycemics, and disulfiram. Inform your doctor about all other medications you are taking.
Q9: How should Metronidazole + Norfloxacin be stored?
A: Store at room temperature, away from excessive heat, moisture, and direct light. Keep out of reach of children.
Q10: Can Metronidazole + Norfloxacin be used to treat all types of infections?
A: No. It is effective against specific types of bacterial and parasitic infections. Its use is determined by the causative pathogen and the site of infection. It is essential to consult with a doctor for appropriate diagnosis and treatment.
