Metronidazole

	IUPAC Name	2-(2-methyl-5-nitro-1''H''-imidazol-1-yl)ethanol
	CAS Number	443-48-1
	ATC Prefix	J01
	ATC Suffix	XD01
	PubChem	4173
	DrugBank	APRD00631
	chemical Formula	C<sub>6</sub>H<sub>9</sub>N<sub>3</sub>O<sub>3</sub>
	molecular Weight	17115
	bioavailability	100% (oral)<br />59%–94% (rectal)
	metabolism	Hepatic
	elimination Half-life	6–7 hours
	excretion	60-80% Renal <br />6–15% Biliary
	pregnancy Category	B2 ( Aust )
	legal Status	Schedule 4 ( Aust )
	routes Of Administration	oral, Rectal , IV

Metronidazole ( Antibiotic drug used in the treamtent of infections caused by susceptible organisms particularly Anaerobic Bacteria and Protozoa . It is marketed by Sanofi-Aventis under the trade name '''Flagyl''', and also by various generic manufacturers. Metronidazole is also used in the treament of the Dermatological condition Rosacea , where it is marketed by Galderma under the trade name '''Rozex''' and '''MetroGel'''.

MODE OF ACTION

Within anaerobic bacteria and sensitive protozoal cells, the nitro group of metronidazole is chemically reduced by Ferredoxin (or ferredoxin-linked metabolic process). The reduction products appear to be responsible for killing the organisms by reacting with various intracellular macromolecules by interfering with DNA synthesis.

INDICATIONS

Systemic metronidazole is indicated for the treatment of:

Gram-positive and Gram-negative anaerobic bacterial infections, e.g. '' Bacteroides Fragilis ''

Protozoal infections, e.g. Giardiasis , Trichomoniasis

Pseudomembranous Colitis ('' Clostridium Difficile '')

Dental infections, including acute Gingivitis

Intra-abdominal infections

Aspiration Pneumonia

Lung Abscess

Bacterial Vaginosis

Pelvic Inflammatory Disease

Amoebiasis (intestinal and extra-intestinal)

Surgical prophylaxis

Eradication of '' Helicobacter Pylori '' (as part of a multi-drug regimen)

Topical metronidazole is indicated for the treatment of Rosacea , and has been used in the treatment of malodorous Fungating wounds. (Rossi, 2006)

Prevention of preterm births

Metronidazole has also been used in women to prevent preterm birth associated with Bacterial Vaginosis , amongst other risk factors including the presence of cervicovaginal fetal fibronectin (fFN). A Randomised Controlled Trial demonstrated that metronidazole was ineffective in preventing preterm delivery in high-risk pregnant women and, conversely, the incidence of preterm delivery was actually higher in women treated with metronidazole. (Shennan et al., 2006)

ADVERSE EFFECTS

Common , Stomatitis , dark urine, and/or Paraesthesia . (Rossi, 2006)

High doses and/or long-term systemic treatment with metronidazole is associated with the development of furry black tongue, Leukopenia , Neutropenia , increased risk of Peripheral Neuropathy and/or CNS toxicity. (Rossi, 2006)

Metronidazole is listed on the IARC as a potential human carcinogen, however some of the testing methods have been questioned, although it has been proven to cause cancer in experimental animals (http://ntp.niehs.nih.gov/ntp/roc/eleventh/profiles/s112metr.pdf). However, it appears to have a fairly low potential for cancer risk and the benefits most likely outweight the risks.

Common ADRs associated with topical metronidazole therapy include local redness, dryness, and/or skin irritation; and eye watering (if applied near eyes). (Rossi, 2006)

Interaction with ethanol

Co-administration of metronidazole and Ethanol (alcohol) results, rarely, in a Disulfiram -like reaction (nausea, vomiting, flushing, Tachycardia ). Consumption of alcohol should be avoided by patients during systemic metronidazole therapy and for at least 24 hours after completion of treatment. (Rossi, 2006) However, the occurrence of this reaction in the clinical setting has recently been questioned by some authors. (Williams & Woodcock, 2000; Visapaa et al., 2002)

REFERENCES

Rossi S, editor. Australian Medicines Handbook 2006. Adelaide: Australian Medicines Handbook; 2006. ISBN 0-9757919-2-3

Shennan A, Crawshaw S, Briley A, Hawken J, Seed P, Jones G, et al. A randomised controlled trial of metronidazole for the prevention of preterm birth in women positive for cervicovaginal fetal fibronectin: the PREMET Study. ''BJOG'' 2006;113(1):65-74. PMID 16398774

Williams CS, Woodcock KR. Do ethanol and metronidazole interact to produce a disulfiram-like reaction? ''Ann Pharmacother'' 2000;34(2):255-7. PMID 10676835

Visapaa JP, Tillonen JS, Kaihovaara PS, Salaspuro MP. Lack of disulfiram-like reaction with metronidazole and ethanol. ''Ann Pharmacother'' 2002;36(6):971-4. PMID 12022894

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Metronidazole