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Monday, February 7, 2011

metronidazole

Posted by Sampil 5:55 PM, under | No comments

metronidazole
(me troe ni' da zole)
Apo-Metronidazole (CAN), FlagylFlagyl 375, Flagyl ER, Flagyl IV, Flagyl IV RTU, MetroGel, MetroGel-Vaginal, NidaGel (CAN),NoritateProtostat

Pregnancy Category B

Drug classes
Antibiotic
Antibacterial
Amebicide
Antiprotozoal

Therapeutic actions
Bactericidal: Inhibits DNA synthesis in specific (obligate) anaerobes, causing cell death; antiprotozoal-trichomonacidalamebicidal: Biochemical mechanism of action is not known.

Indications
·        Acute infection with susceptible anaerobic bacteria
·        Acute intestinal amebiasis
·        Amebic liver abscess
·        Trichomoniasis (acute and partners of patients with acute infection)
·        Preoperative, intraoperative, postoperative prophylaxis for patients undergoing colorectal surgery
·        Topical application: Treatment of inflammatory papules, pustules, and erythema of rosacea
·        Unlabeled uses: Prophylaxis for patients undergoing gynecologic, abdominal surgery; hepatic encephalopathy; Crohn's disease; antibiotic-associatedpseudomembranous colitis; treatment of Gardnerella vaginalisgiardiasis (use recommended by the CDC)

Contraindications and cautions
·        Contraindicated with hypersensitivity to metronidazole; pregnancy (do not use for trichomoniasis in first trimester).
·        Use cautiously with CNS diseases, hepatic disease, candidiasis (moniliasis), blood dyscrasias, lactation.

Available forms
Tablets—250, 500 mg; ER tablets—750 mg; capsules—375 mg; powder for injection—500 mg; injection—500 mg/100 mL; lotion, cream, gel—0.75%; cream—1%; vaginal gel—0.75%

Dosages
ADULTS
Oral
·        Amebiasis: 750 mg/tid PO for 5–10 days. (In amebic dysentery, combine with iodoquinol 650 mg PO tid for 20 days.)
·        Antibiotic-associated pseudomembranous colitis: 1–2 g/day PO for 7–10 days.
·        Gardnerella vaginalis: 500 mg bid PO for 7 days.
·        Giardiasis: 250 mg tid PO for 7 days.
·        Trichomoniasis: 2 g PO in 1 day (1-day treatment) or 250 mg tid PO for 7 days.
IV
·        Anaerobic bacterial infection: 15 mg/kg IV infused over 1 hr; then 7.5 mg/kg infused over 1 hr q 6 hr for 7–10 days, not to exceed 4 g/day.
·        Prophylaxis: 15 mg/kg infused IV over 30–60 min and completed about 1 hr before surgery. Then 7.5 mg/kg infused over 30–60 min at 6- to 12-hr intervals after initial dose during the day of surgery only.
Topical (MetroGel)
·        Treatment of inflammatory papules, pustules, and erythema of rosacea: Apply and rub in a thin film twice daily, morning and evening, to entire affected areas after washing; results should be seen within 3 wk; treatment through 9 wk has been effective.
Vaginal (MetroGel-Vaginal)
·        In non-pregnant women: 1 applicatorful intravaginally one to two times/day for 5 days.
PEDIATRIC PATIENTS
·        Anaerobic bacterial infection: Not recommended.
·        Amebiasis: 35–50 mg/kg/day PO in three doses for 10 days.

Pharmacokinetics
Route
Onset
Peak
Oral
Varies
1–2 hr
IV
Rapid
1–2 hr

Metabolism: Hepatic; T1/2: 6–8 hr
Distribution: Crosses placenta; enters breast milk
Excretion: Feces, urine

IV facts
Preparation: Reconstitute by adding 4.4 mL of sterile water for injection, bacteriostatic water for injection, 0.9% sodium chloride injection, bacteriostatic 0.9% sodium chloride injection to the vial and mix thoroughly. Resultant volume is 5 mL with a concentration of 100 mg/mL. Solution should be clear to pale yellow to yellow-green; do not use if cloudy or if containing precipitates; use within 24 hr; protect from light. Add reconstituted solution to glass or plastic container containing 0.9% sodium chloride injection, 5% dextrose injection or lactated Ringer's; discontinue other solutions while running metronidazole.
Infusion: Before administration, add 5 mEq sodium bicarbonate injection for each 500 mg used (if not using premixed bags); mix thoroughly. Do not refrigerate neutralized solution. Do not administer solution that has not been neutralized. Infuse over 1 hr.

Adverse effects
·        CNS: Headache, dizziness, ataxia, vertigo, incoordination, insomnia, seizures, peripheral neuropathy, fatigue
·        GI: Unpleasant metallic taste, anorexia, nausea, vomiting, diarrhea, GI upset, cramps
·        GU: Dysuria, incontinence, darkening of the urine
·        Local: Thrombophlebitis (IV); redness, burning, dryness, and skin irritation (topical)
·        Other: Severe, disulfiram-like interaction with alcohol, candidiasis (superinfection)

Interactions
·        Decreased effectiveness with barbiturates
·        Disulfiram-like reaction (flushing, tachycardia, nausea, vomiting) with alcohol
·        Psychosis if taken with disulfiram
·        Increased bleeding tendencies with oral anticoagulants
·        Falsely low (or zero) values in AST, ALT, LDH, triglycerides, hexokinase glucose tests

Nursing considerations
Assessment
·        History: CNS or hepatic disease; candidiasis (moniliasis); blood dyscrasias; pregnancy; lactation
·        Physical: Reflexes, affect; skin lesions, color (with topical application); abdominal examination, liver palpation; urinalysis, CBC, LFTs

Interventions
·        WARNING: Avoid use unless necessary. Metronidazole is carcinogenic in some rodents.
·        Administer oral doses with food.
·        Apply topically (MetroGel) after cleansing the area. Advise patient that cosmetics may be used over the area after application.
·        Reduce dosage in hepatic disease.

Teaching points
·        Take full course of drug therapy; take the drug with food if GI upset occurs.
·        Do not drink alcohol (beverages or preparations containing alcohol, cough syrups); severe reactions may occur.
·        Your urine may appear dark; this is expected.
·        Refrain from sexual intercourse during treatment for trichomoniasis unless partner wears a condom.
·        Apply the topical preparation by cleansing the area and then rubbing a thin film into the affected area. Avoid contact with the eyes. Cosmetics may be applied to the area after application.
·        You may experience these side effects: Dry mouth with strange metallic taste (frequent mouth care, sucking sugarless candies may help); nausea, vomiting, diarrhea (eat frequent small meals).
·        Report severe GI upset, dizziness, unusual fatigue or weakness, fever, chills.

Adverse effects in Italic are most common; those in Bold are life-threatening.

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