Metronidazole (Page 3 of 4)


The use of dosages of metronidazole higher than those recommended has been reported. These include the use of 27 mg/kg three times a day for 20 days, and the use of 75 mg/kg as a single loading dose followed by 7.5 mg/kg maintenance doses. No adverse reactions were reported in either of the two cases.

Single oral doses of metronidazole, up to 15 g, have been reported in suicide attempts and accidental overdoses. Symptoms reported include nausea, vomiting, and ataxia.

Oral metronidazole has been studied as a radiation sensitizer in the treatment of malignant tumors. Neurotoxic effects, including seizures and peripheral neuropathy, have been reported after 5 to 7 days of doses of 6 to 10.4 g every other day.


There is no specific antidote for overdose; therefore, management of the patient should consist of symptomatic and supportive therapy.


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 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.

Patients with severe hepatic disease metabolize metronidazole slowly, with resultant accumulation of metronidazole and its metabolites in the plasma. Accordingly, for such patients, doses below those usually recommended should be administered cautiously. Close monitoring of plasma metronidazole levels and toxicity is recommended.1

In patients receiving metronidazole injection in whom gastric secretions are continuously removed by nasogastric aspiration, sufficient metronidazole may be removed in the aspirate to cause a reduction in serum levels.

The dose of Metronidazole Injection, USP should not be specifically reduced in anuric patients since accumulated metabolites may be rapidly removed by dialysis.

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.


For surgical prophylactic use, to prevent postoperative infection in contaminated or potentially contaminated colorectal surgery, the recommended dosage schedule for adults is:

  1. 15 mg/kg infused over 30 to 60 minutes and completed approximately one hour before surgery, followed by:
  2. 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.

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. The usual adult oral dosage is 7.5 mg/kg every six hours.

A maximum of 4 g should not be exceeded during a 24-hour period.

Caution: Metronidazole Injection, USP is to be administered by slow intravenous drip infusion only, either as a continuous or intermittent infusion. Intravenous 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, USP contains 13.5 mEq of sodium.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Do not use if cloudy or precipitated or if the container is not intact.

Use sterile equipment. It is recommended that the intravenous administration apparatus be replaced at least once every 24 hours.


Metronidazole Injection, USP is supplied in 100 mL bag, each containing an isotonic buffered solution of 500 mg metronidazole. Metronidazole Injection, USP is sterile premixed solution intended for single dose only.

NDC Metronidazole Injection, USP (5 mg per mL) Package Factor
25021-131-82 500 mg per 100 mL single-dose flexible 24 bags per carton
container bag

Storage Conditions

Store at 20° to 25°C (68° to 77°F). [See USP Controlled Room Temperature.]

Exposure of pharmaceutical products to heat should be minimized. Avoid excessive heat. Protect from freezing. It is recommended that the product be stored at room temperature (25°C); however, brief exposure up to 40°C does not adversely affect the product.

Protect from light until use.

Sterile, Nonpyrogenic, Preservative-free, PVC-free, DEHP-free. The container and container closure are not made with natural rubber latex.


  1. Ralph ED, Kirby WMM: Bioassay of Metronidazole With Either Anaerobic or Aerobic Incubation, J. Infect. Dis. 132:587–591 (Nov.) 1975, or Gulaid, et al.: Determination of Metronidazole and its Major Metabolites in Biological Fluids by High Pressure Liquid Chromatography, Br. J. Clin. Pharmacol. 6:430–432, 1978.

Mfd. for SAGENT Pharmaceuticals

Schaumburg, IL 60195 (USA)

Made in Switzerland

©2021 Sagent Pharmaceuticals, Inc.

Revised: May 2021

SAGENT Pharmaceuticals®

Directions for Use


For intravenous infusion only

Store the individual container in the aluminum overwrap until ready to use.

Use sterile equipment.

Before use, perform the following checks:

Read the label. Ensure solution is the one ordered and is within the expiration date.

Inspect the solution in good light for cloudiness, haze or particulate matter; check for minute leaks by squeezing the bag firmly. Any container which is suspect should not be used. If leaks are found, discard container as sterility may be compromised.

Use only if solution is clear and the container is undamaged.

Single dose plastic container. Discard unused portion.

Consult Package Insert for complete product information.

Preparation for Administration

  1. Close flow control clamp of administration set.
  2. Caution – adding additives into the Metronidazole Injection solution bag is prohibited. 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, etc.) that may contact the drug solution.
  3. Remove cover from port at bottom of container.
  4. Insert piercing pin of administration set into port with a twisting motion until the pin is firmly seated.

    NOTE: See full directions on administration set carton.

  5. Suspend container from hanger.
  6. Squeeze and release drip chamber to establish proper fluid level in chamber during infusion of Metronidazole Injection, USP.
  7. Open flow control clamp to expel air from set. Close clamp.
  8. Regulate rate of administration with flow control clamp.

Mfd. for SAGENT Pharmaceuticals

Schaumburg, IL 60195 (USA)

Made in Switzerland

©2019 Sagent Pharmaceuticals, Inc.

May 2019

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