[e-drug] EDL: Metronidazole and other nitroimidazoles (cont)

["Jonathan Dartnell" <jdartnell@tg.com.au>]

E-drug: EDL: Metronidazole and other nitroimidazoles (cont)
---------------------------------------------

The frequency of metronidazole dosing, and the possibility of using other
nitroimidazoles, is dependent on the many indications for these drugs.

For the treatment of mixed aerobic and anaerobic bacterial infections,
although registered product information (data sheets) for metronidazole have
recommended 8-hourly dosing, Therapeutic Guidelines: Antibiotic [1]
recommend a dose of 400mg orally and 500mg intravenously, with a 12-hourly
dosing schedule. This is based on an analysis of pharmacokinetics and
minimum inhibitory concentrations of the pathogens involved. For example,
pharmacokinetic data suggests that metronidazole 400mg orally 12-hourly can
provide 100% time above MIC for Bacteroides fragilis. Unfortunately there
are few clinical studies where 12-hourly metronidazole has been studied.

For some intraluminal infections, 8-hourly dosing has been recommended. For
example for amoebiasis metronidazole 600mg orally, 8-hourly may be used.

For other infections, eg giardiasis, a once daily metronidazole dose can be
used, although a tinidazole stat dose may be superior. For bacterial
vaginosis, metronidazole 400mg orally, 12-hourly, is recommended but also a
single dose of metronidazole or tinidazole 2g may be used.  However, 
the cure rate
is lower and re-treatment may be necessary. For trichomoniasis, tinidazole
OR metronidazole 2g orally, as a single dose, may be used.

In Australia, there is no IV preparation available, so tinidazole is not an
alternative in many indications.

Jonathan Dartnell
Production Manager
Therapeutic Guidelines
Level 2, 55 Flemington Road, North Melbourne, Vic 3051, Australia
Telephone: 61 3 9326 9959
Facsimile: 61 3 9326 5632
Email: jdartnell@tg.com.au
Website: http//www.tg.com.au

[1] Therapeutic Guidelines: Antibiotic. 11 ed. Melbourne: Therapeutic
Guidelines Limited; 2000.
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