10-mL Vials, containing 160 mg trimethoprim (16 mg/mL) and 800 mg sulfamethoxazole (80 mg/mL) for infusion with 5% dextrose in water. Boxes of 10 (NDC 0004-1955-01).
30-mL Multidose Vials, each 5 mL containing 80 mg trimethoprim (16 mg/mL) and 400 mg sulfamethoxazole (80 mg/mL) for infusion with 5% dextrose in water.
Method of Preparation:
Bactrim IV Infusion must be diluted. EACH 5 ML SHOULD BE ADDED TO 125 ML OF 5% DEXTROSE IN WATER. After diluting with 5% dextrose in water the solution should not be refrigerated and should be used within 6 hours. If a dilution of 5 mL per 100 mL of 5% dextrose in water is desired, it should be used within 4 hours. If upon visual inspection there is cloudiness or evidence of crystallization after mixing, the solution should be discarded and a fresh solution prepared.
Multidose Vials: After initial entry into the vial, the remaining contents must be used within 48 hours.
EACH 5 ML OF BACTRIM IV INFUSION SHOULD BE ADDED TO 125 ML OF 5% DEXTROSE IN WATER.
Note: In those instances where fluid restriction is desirable , each 5 mL may be added to 75 mL of 5% dextrose in water. Under these circumstances the solution should be mixed just prior to use and should be administered within 2 hours. If upon visual inspection there is cloudiness or evidence of crystallization after mixing, the solution should be discarded and a fresh solution prepared.
DO NOT MIX BACTRIM IV INFUSION-5% DEXTROSE IN WATER WITH DRUGS OR SOLUTIONS IN THE SAME CONTAINER.
The solution should be given by intravenous infusion over a period of 60 to 90 minutes. Rapid infusion or bolus injection must be avoided. Bactrim IV Infusion should not be given intramuscularly.
From: Bactrim Indications, Dosage, Storage, Stability - Trimethoprim and Sulfamethoxazole - RxList Monographs
So I would take from that :
* Your dose is 160mg (trimethoprim) IV every 6hrs
* So: 160mg (10mls solution) should be diluted in 250mls D5W, then infused over 60-90 mins.
Make sure you check the compatibilities on the package insert before piggybacking with other fluids etc.