What dose of Flagyl (metronidazole) is given to an outpatient with a ruptured appendix?

From the Guidelines

For a patient with a burst appendix being treated as an outpatient, Flagyl (metronidazole) is typically given at a dose of 500 mg orally every 8 hours or 1500 mg every 24 hours as part of a combination antibiotic regimen, as recommended by the most recent guidelines 1. The choice of metronidazole is based on its efficacy against anaerobic bacteria commonly found in intra-abdominal infections following appendix rupture.

• The medication should be taken with food to minimize gastrointestinal side effects.
• Patients should avoid alcohol during treatment and for at least 48 hours after completing the course due to potential disulfiram-like reactions.
• The total duration of antibiotic therapy is generally 7-10 days, depending on the patient's clinical response, with a recommendation against prolonging antibiotics longer than 3–5 days postoperatively in case of complicated appendicitis with adequate source-control 1.
• Metronidazole is usually prescribed alongside another antibiotic with gram-negative coverage, such as ciprofloxacin 500 mg twice daily, as part of a combination regimen to ensure broad-spectrum coverage.
• It's essential to note that most patients with a ruptured appendix require initial inpatient management with IV antibiotics and surgical intervention before transitioning to oral antibiotics for outpatient treatment.
• The use of metronidazole in combination with other antibiotics is supported by guidelines that emphasize the importance of covering both aerobic and anaerobic bacteria in the treatment of complicated intra-abdominal infections 1.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION In elderly patients the pharmacokinetics of metronidazole may be altered and therefore monitoring of serum levels may be necessary to adjust the metronidazole dosage accordingly. TREATMENT OF ANAEROBIC INFECTIONS The recommended dosage schedule for Adults is: Loading Dose 15 mg/kg infused over one hour (approximately 1 g for a 70-kg adult). Maintenance Dose 7. 5 mg/kg infused over one hour every six hours (approximately 500 mg for a 70-kg adult). PROPHYLAXIS For surgical prophylactic use, to prevent postoperative infection in contaminated or potentially contaminated colorectal surgery, the recommended dosage schedule for adults is:a 15 mg/kg infused over 30 to 60 minutes and completed approximately one hour before surgery, followed by:b. 7. 5 mg/kg infused over 30 to 60 minutes at 6 and 12 hours after the initial dose

The dose of flagyl (metronidazole) for a patient with a burst appendix is 15 mg/kg infused over one hour as a loading dose, followed by 7.5 mg/kg infused over one hour every six hours as a maintenance dose 2.

• The loading dose is approximately 1 g for a 70-kg adult.
• The maintenance dose is approximately 500 mg for a 70-kg adult.

From the Research

Antibiotic Treatment for Acute Appendicitis

• The standard treatment for acute appendicitis is appendectomy, but antibiotic therapy has been proposed as an alternative in selected patients 3, 4, 5.
• The antibiotics used for treating acute appendicitis include amoxicillin + clavulanic acid, cefotaxime, fluoroquinolones, metronidazole, and tinidazole 4, 5, 6.
• The duration of antibiotic treatment can vary, but studies have shown that a shortened course of 5-8 days can be effective in treating perforated appendicitis in children 6.
• For adults with uncomplicated acute appendicitis, a course of 8 to 15 days of antibiotics has been used 4.

Specific Antibiotic Regimens

• One study used intravenous piperacillin plus tazobactam, followed by 9 days of oral ciprofloxacin plus metronidazole 5.
• Another study compared Amoxicillin/Clavulanate to Ciprofloxacin/Metronidazole and found that the choice of antibiotic did not affect readmission rates 6.

Dosage of Flagyl (Metronidazole)

• The dosage of Flagyl (metronidazole) is not explicitly stated in the provided studies, but it is often used in combination with other antibiotics such as ciprofloxacin or amoxicillin/clavulanate 4, 5, 6.
• The typical dosage of metronidazole for treating acute appendicitis is not specified in the provided evidence, and therefore, it is not possible to determine the exact dose given to a patient with a burst appendix.