Metronidazole / Flagyl

- Discussion and Dosage:
    - type of reducing compound that leads to the formation of oxygen free radicals which are toxic to anaerobic bacteria;
    - for amebiasis, trichomoniasis, B.fragilis, C. difficile;
    - is effective for B.fragilis which is resistant to clindamycin, chloramphenicol, penicillin G;
    - amebic: 750mg PO qd (5-10 days);
    - trichomoniasis: 250mg PO tid (7 days) or 2 gm PO in 1 dose;
    - IV form for serious anaerobic: 500mg IV q6hr;
    - or for Anaerobic try:IV loading 15mg / kg then 7.5mg/kg q6hr;
    - maximum daily dose 4mg; IV should be infused over 1hr;
    - peds: Anaerobic infections: 30 mg/kg/day divided q6hr;
    - amebic dysentery: 35-50 mg/kg/24hr in 3 DD for 5-10 days;
    - giardia lamblia: 5mg/kg/dose tid for 10 days;
    - bioavailability is almost 100%, and 500 mg PO gives high ATB levels;

- Cautions:
    - must decrease with severe liver dz;
    - no activity against aerobes;  contraidicated with hypersensitivity;
    - note: Diffusion from blood into CSF adequate w/ or w/o Inflammation;
    - ratio of CSF to Blood Level (%):
           - normal meninges: 16-43; inflammed meninges: 100;
    - dosing regimens for patients with renal insufficiency:
           - dose for 70 kg adult {gm/dosing interval in hours}):
           - CrCl: >80: 0.5-1/8; CrCl:50-79: 0.5-1/8; CrCl:30-49:0.5-1/8; CrCl:10-29: 0.5-1/8;;
           - 20% of drug will be excreted in to urine (w/ nl RF(x))
           - doses do not need to be decreased in renal failure, however, flaggyl metabolites will accumulate with usage;
    - paresthesia: peripheral neuropathy: convulsions;
    - will interact with ETOH, disulfiram, will increase effects of oral anticoag;
    - phenobarbital will decr effects of flagyl;
    - flagyl will decr clearance of Phenytoin

Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Thursday, December 6, 2012 3:53 pm