- 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