DOSAGE AND ADMINISTRATION
In elderly patients the pharmacokinetics of metronidazole may be altered and, therefore, monitoring of serum levels may be necessary to adjust the metronidazole dosage accordingly.
Treatment of Anaerobic Bacterial Infections:
The recommended dosage schedule for Adults is:
Loading Dose | 15 mg/kg infused over one hour (approximately 1 g for a 70-kg adult). |
Maintenance Dose | 7.5 mg/kg infused over one hour every six hours (approximately 500 mg for a 70-kg adult). The first maintenance dose should be instituted six hours following the initiation of the loading dose. |
Parenteral therapy may be changed to oral metronidazole when conditions warrant, based upon the severity of the disease and the response of the patient to treatment with Metronidazole Injection, USP treatment. The usual adult oral dosage is 7.5 mg/kg every six hours (approximately 500 mg for a 70-kg adult).
A maximum of 4 g should not be exceeded during a 24-hour period.
The usual duration of therapy is 7 to 10 days; however, infections of the bone and joint, lower respiratory tract, and endocardium may require longer treatment.
Dosage Adjustments
Patients with Severe Hepatic Impairment
For patients with severe hepatic impairment (Child-Pugh C), the metronidazole dose should be reduced by 50% (see CLINICAL PHARMACOLOGY and PRECAUTIONS).
Patients Undergoing Hemodialysis
Hemodialysis removes significant amounts of metronidazole and its metabolites from systemic circulation. The clearance of metronidazole will depend on the type of dialysis membrane used, the duration of the dialysis session, and other factors. If the administration of metronidazole cannot be separated from a hemodialysis session, supplementation of metronidazole dosage following a hemodialysis session should be considered, depending on the patient's clinical situation (see CLINICAL PHARMACOLOGY).
Prophylaxis
For surgical prophylactic use, to prevent postoperative infection in contaminated or potentially contaminated colorectal surgery, the recommended dosage schedule for adults is:
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- 15 mg/kg infused over 30 to 60 minutes and completed approximately one hour before surgery; followed by
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- 7.5 mg/kg infused over 30 to 60 minutes at 6 and 12 hours after the initial dose.
It is important that (1) administration of the initial preoperative dose be completed approximately one hour before surgery so that adequate drug levels are present in the serum and tissues at the time of initial incision, and (2) Metronidazole Injection, USP be administered, if necessary, at 6-hour intervals to maintain effective drug levels. Prophylactic use of Metronidazole Injection, USP should be limited to the day of surgery only, following the above guidelines.
CAUTION: Metronidazole Injection, USP is to be administered by slow intravenous drip infusion only, either as a continuous or intermittent infusion. I.V. admixtures containing metronidazole and other drugs should be avoided. Additives should not be introduced into this solution. If used with a primary intravenous fluid system, the primary solution should be discontinued during metronidazole infusion. DO NOT USE EQUIPMENT CONTAINING ALUMINUM (e.g., NEEDLES, CANNULAE) THAT WOULD COME IN CONTACT WITH THE DRUG SOLUTION.
Metronidazole Injection, USP is a ready-to-use isotonic solution. NO DILUTION OR BUFFERING IS REQUIRED. Do not refrigerate. Each container of Metronidazole Injection contains 14 mEq of sodium.
Do not use if cloudy or precipitated or if the seal is not intact.
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.
Use sterile equipment. It is recommended that the intravenous administration apparatus be replaced at least once every 24 hours.