What is the frequency of Metronidazole (Flagyl) 500mg intravenous (IV) administration for choledochitis?

From the Guidelines

Flagyl (metronidazole) 500mg IV should be administered every 8 hours for the treatment of choledocho infections, as this dosing schedule is supported by the most recent and highest quality evidence. When considering the treatment of choledocho infections, it is crucial to prioritize the most effective antibiotic regimen to minimize morbidity, mortality, and improve quality of life. According to the guidelines by the Surgical Infection Society and the Infectious Diseases Society of America 1, the recommended initial intravenous adult dosage of metronidazole for empiric treatment of complicated intra-abdominal infection, which includes choledocho infections, is 500 mg every 8–12 hours or 1500 mg every 24 hours. Some key points to consider when administering metronidazole include:

• The total daily dose is 1500mg, divided into three equal doses, to maintain adequate blood levels of the antibiotic and effectively target anaerobic bacteria commonly involved in biliary infections.
• Treatment duration generally ranges from 5-10 days depending on clinical response, with many cases requiring 7 days of therapy.
• Metronidazole works by disrupting bacterial DNA, making it particularly effective against anaerobes like Bacteroides fragilis that are often present in biliary infections.
• It's essential to note that metronidazole is usually part of a broader antibiotic regimen that also covers gram-negative organisms, typically including a third-generation cephalosporin or fluoroquinolone, as recommended by the guidelines 1.
• Renal dose adjustment is generally not required, but liver dysfunction may necessitate dose reduction since metronidazole is primarily metabolized hepatically. The guidelines provided by the Surgical Infection Society and the Infectious Diseases Society of America 1 serve as the foundation for this recommendation, emphasizing the importance of evidence-based practice in treating choledocho infections.

From the FDA Drug Label

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).

• The recommended maintenance dose of Flagyl (metronidazole) 500mg IV for adults is administered every six hours.
• The loading dose is given first, and the first maintenance dose should be instituted six hours following the initiation of the loading dose 2.

From the Research

Frequency of Flagyl 500mg IV for Choledocho

• The provided studies do not specifically mention the frequency of Flagyl 500mg IV for choledocho.
• However, the studies discuss the treatment and management of choledocholithiasis and cholangitis, which may involve the use of antibiotics such as Flagyl (metronidazole) 3, 4, 5, 6.
• The Tokyo Guidelines 2018 provide recommendations for antimicrobial therapy in acute cholangitis and cholecystitis, but do not specify the use of Flagyl 500mg IV 6.
• A study on empirical antibiotics for acute cholecystitis compares the use of first-generation and second-generation cephalosporins, but does not mention Flagyl 7.
• There is no direct evidence in the provided studies to determine the frequency of Flagyl 500mg IV for choledocho.