antibiotic. It enters bacterial cell walls and disrupts DNA and inhibits DNA synthesis in certain microorganisms.
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Pharmacokinetics of Metronidazole and Tinidazole
Metronidazole is metabolized presumably in the liver and excreted mainly in urine, but elimination is not decreased in patients with renal insufficiency. However, because metronidazole metabolites may accumulate in patients with end-stage renal disease, these patients should be monitored for metronidazole-associated adverse effects such as central nervous system effects, including headaches, convulsions, and peripheral neuropathy (mainly numbness or paresthesias in an extremity).
metronidazole, allowing for less frequent dosing.
Indications for Metronidazole and Tinidazole
All obligate anaerobic bacteria (it is inactive against facultative anaerobic and aerobic bacteria)
Certain protozoan parasites (eg, Trichomonas vaginalis, Entamoeba histolytica, Giardia intestinalis [lamblia])
Metronidazole is used primarily for infections caused by obligate anaerobes, often with other antimicrobials. Metronidazole is the antibiotic of choice for bacterial vaginosis. It also has other clinical uses (see table ).
Some Clinical Uses of Metronidazole
Indication | Comments |
|---|---|
Infections due to obligate anaerobes (eg, intra-abdominal, pelvic, soft-tissue, periodontal, and odontogenic infections; lung abscess) | Often used with other antimicrobials for potentially polymicrobial infections |
Antibiotic of choice | |
Central nervous system infections (meningitis, brain abscess) | — |
Septicemia | — |
Prophylaxis before intestinal surgery | — |
Clostridioides (formerly Clostridium) difficile–induced diarrhea (pseudomembranous colitis) | No longer recommended as a first-line antibiotic vancomycin for severe cases |
Peptic ulcers due to Helicobacter pylori | For treatment and prevention of relapses Used with other medications |
Topical or oral use |
Contraindications to Metronidazole and Tinidazole
Use of Metronidazole and Tinidazole During Pregnancy and Breastfeeding
metronidazole during pregnancy; however, in some studies, cleft lip (with or without cleft palate) was reported in neonates of women who took metronidazole during the first trimester. Some experts advise avoiding metronidazole during the first trimester, although the Centers for Disease Control and Prevention's (CDC) 2021 sexually transmitted infections treatment guidelines indicate that a single 2-g dose can be used at any stage of pregnancy to treat trichomoniasis.
tinidazole is avoided during pregnancy. Breastfeeding should be deferred for 72 hours after a single 2-g oral dose of tinidazole.
Adverse Effects of Metronidazole and Tinidazole
Gastrointestinal disturbances
Central nervous system effects and peripheral neuropathy
Disulfiram-like reaction
Metronidazole can cause a metallic taste and dark urine.
Dosing Considerations for Metronidazole and Tinidazole
Metronidazole doses are usually decreased 50% in patients with significant liver disease; tinidazole has not been studied in liver disease and should be used with caution if at all.
More Information
The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
Centers for Disease Control and Prevention (CDC): Sexually Transmitted Infections Treatment Guidelines (2021)
