Metronidazole	(meh-troe-NID-uh-zole)
Trade Name(s):	Flagyl   ·Tablets 250 mg   ·Tablets 500 mg   Flagyl ER   ·Tablets, extended-release 750 mg   Flagyl 375   ·Capsules 375 mg   Flagyl I.V.   ·Powder for Injection, lyophilized 500 mg   Flagyl I.V. RTU   ·Injection 5 mg/mL   Metric 21   ·Tablets 250 mg   MetroCream   ·Cream 0.75%   MetroGel   ·Gel 0.75%   MetroGel-Vaginal   ·Gel 0.75%   MetroLotion   ·Lotion 0.75%   Noritate   ·Cream 1%   Protostat   ·Tablets 250?mg   ·Tablets 500 mg Apo-Metronidazole Florazole ER Nida Gel Rosasol Indicates Canadian Trade Name.
Class:	Anti-infective agent GI agent Vaginal preparation
Action:	Enters bacterial or protozoal cell and impairs synthesis of DNA, resulting in cell death. Absorption: Oral metronidazole is well absorbed; topical application is less complete and more prolonged. Following administration, T max is 1 to 2 h, and C max is 25 mg/mL. Oral bioavailability is not affected by food, but peak serum levels will be delayed to 2 h.
	Distribution: Metronidazole appears in cerebrospinal fluid, saliva, and breast milk in concentrations similar to those found in plasma. Less than 20% is protein bound.
	Metabolism: Metabolites are 2 – hydroxymethyl and acidic metabolite.
	Excretion: Routes of elimination are via urine (60% to 80%) and feces (6% to 15%). Renal Cl is approximately 10 ? mL/min per 1.73 ? m 2 . The t ½ is 8 h in healthy adults, and the hydroxy-metabolite t ½ is 15 h.
	Special Populations: Hepatic Function Impairment - Patients with hepatic function impairment metabolized metronidazole slower; accumulation of drug may occur. Cautiously administer doses below the usual recommended dose. Elderly - Because the pharmacokinetics of metronidazole may be altered in the elderly, monitoring of serum levels may be necessary to adjust the dosage accordingly.
Indications:	Treatment of serious infections caused by susceptible anaerobic bacteria; prophylaxis of postoperative infection in patients undergoing colorectal surgery; treatment of amebiasis; treatment of trichomoniasis and asymptomatic partners of infected patients; bacterial vaginosis ( Flagyl ER only).
	Topical Treatment of inflammatory papules, pustules, and erythema of acne rosacea.
	Vaginal Treatment of bacterial vaginosis.
Indications:	Unlabeled use(s): Treatment of hepatic encephalopathy, Crohn disease, antibiotic-associated pseudomembranous colitis, Helicobacter pylori infections.
Contraindications:	Hypersensitivity to nitroimidazole derivatives or any component of the products; first trimester of pregnancy in patients with trichomoniasis.
Interactions:
	Anticoagulants Anticoagulant effect may be increased.
	Barbiturates, phenytoin Therapeutic failure of metronidazole may occur.
	Cimetidine May prolong the t ½ and decrease plasma Cl of metronidazole.
	Disulfiram Concurrent use may result in acute psychosis or confusional state. Do not give metronidazole to patients who have taken disulfiram within last 2 wk.
	Ethanol Disulfiram-like reaction including flushing, palpitations, tachycardia, nausea, and vomiting may occur with concurrent use.
	Lithium Plasma levels may be elevated by metronidazole, increasing the risk of lithium toxicity.
	INCOMPATIBILITIES: Do not use aluminum-containing equipment with metronidazole because solution will turn orange/rust color.
Lab Test Interferences:	May interfere with chemical analyses for AST, ALT, LDH, triglycerides, and hexokinase glucose; zero values may occur.
Adverse Reactions:	When known, dose form and percentage are stated.
	cardiovascular: Flattening of T-wave.
	cns: Seizures; peripheral neuropathy; dizziness; vertigo; incoordination; ataxia; confusion; depression; insomnia; syncope; irritability; weakness.
	Flagyl ER Headache (18%); dizziness (4%).
	MetroGel Vaginal Headache (5%); dizziness (2%).
	dermatologic: Thrombophlebitis; urticaria; erythematous rash; flushing.
	MetroGel Vaginal Generalized itching or rash, skin irritation, transient skin erythema, mild skin dryness and burning (2%).
	MetroLotion/Cream/Gel Topical: erythema, local allergic reaction, contact dermatitis, pruritus, skin discomfort (burning, stinging), worsening of rosacea, dry skin, transient redness.
	eent: Metallic taste; glossitis; stomatitis.
	Flagyl ER Rhinitis (4%); sinusitis, pharyngitis (3%).
	gi: Nausea; anorexia; vomiting; diarrhea; constipation; epigastric distress; cramps; pseudomembranous colitis; furry tongue; glossitis; stomatitis.
	Flagyl ER Nausea (10%); metallic taste (9%); abdominal pain, diarrhea (4%); dry mouth (2%).
	MetroGel Vaginal GI discomfort (7%); nausea, vomiting (4%); unusual taste (2%); diarrhea, loose stools, decreased appetite (1%).
	gu: Darkening of urine; dysuria; cystitis; sense of pelvic pressure; polyuria; incontinence; vaginal Candida proliferation; decreased libido; proctitis.
	Flagyl ER Vaginitis (15%); genital pruritus (5%); abnormal urine, dysmenorrhea (3%); UTI (2%).
	MetroGel Vaginal Vaginal discharge (12%); symptomatic Candida cervicitis/vaginitis (10%); vulva/vaginal irritative symptoms (9%); pelvic discomfort (3%).
	hematologic: Mild leukopenia; reversible thrombocytopenia.
	respiratory:
	Flagyl ER Upper respiratory tract infection (4%).
	miscellaneous: Hypersensitivity reactions including dermatologic reactions, nasal congestion, dry mouth or vagina, and fever; fleeting joint pain; pancreatitis. Topical or vaginal use may cause similar adverse reactions. After prolonged IV use, thrombophlebitis may occur.
	Flagyl ER Bacterial infection (7%); influenza-like symptoms (6%); moniliasis (3%).
	MetroGel Vaginal Unspecified cramping (1%).
Precautions:
Warning:	Oral and IV metronidazole have been carcinogenic in mice and rats. Avoid unnecessary use.
	Pregnancy: Category B .
	Lactation: Excreted in breast milk.
	Children: Safety and efficacy not established, except for amebiasis.
	Elderly: Monitoring serum levels may be necessary for proper dosing.
	Hepatic function impairment: Patients with severe hepatic disease metabolize drug slowly; use caution and lower dose.
	Candidiasis Known or previously unrecognized candidiasis may present more prominent symptoms during therapy.
	Hematologic effects Use with caution in patients with a history of blood dyscrasia.
	Neurologic effects Seizures and peripheral neuropathy have occurred. Use extra caution with prolonged use, high doses, or history of CNS disease.
Overdosage:	Signs & symptoms Nausea, vomiting, ataxia, seizures, peripheral neuropathy.
Patient/Family Education:	Instruct patient to take exactly as prescribed and not to change dose or discontinue therapy unless advised by health care provider. Instruct patient to notify health care provider if infection does not appear to be improving or appears to be getting worse. Caution patient to avoid alcoholic beverages while taking metronidazole and for at least 1 day (tablets) or 3 days (capsules and extended-release tablets) following completion of therapy. Advise patient that metallic taste is a common adverse reaction of therapy but that this will resolve when therapy has been discontinued. Advise patient to report any other bothersome adverse reactions to health care provider and to immediately report any abnormal neurologic signs or symptoms (eg, seizures, extremity numbness, abnormal skin sensations). Advise patient to take prescribed dose without regard to meals but to take with food if GI upset occurs. Advise patient to take prescribed dose daily, 1 h before or 2 h after a meal. Caution patient to swallow extended-release tablet whole and not crush, chew, or divide. Review instructions for filling applicator, administering medication, and care of applicator. Advise patient that if accidental contact of the gel with the eye(s) occurs, to rinse the eye(s) with copious amounts of cool tap water. Advise patient to notify health care provider if eye irritation persists after rinsing. Advise patient to avoid vaginal intercourse during treatment. Advise patient to discontinue use and notify health care provider if vaginal irritation develops while using the medication. Advise patient to cleanse areas to be treated before applying medication, then apply and rub in a thin film twice daily to entire affected areas. Advise patient that cosmetics may be applied after application of medication but if using lotion, to allow it to dry first. Advise patient that if local irritation occurs to apply the medication less frequently. If irritation persists, advise patient to discontinue use and notify health care provider. Advise patient, family, or caregiver that medication will be prepared and administered by a health care provider in a health care setting. Advise patient to report injection-site pain or redness.