On-call scenario 3: Sources

Last updated: Wednesday, June 05, 2024

Hopefully your suggested resource list looks something like this: 

• SmPC via the emc or MHRA 
• Your local Trust guidelines 

You check the BNF and SmPC and are reassured that IV co-trimoxazole 120 mg/kg per day in divided doses is appropriate to treat PCP/PJP. 

 A quick look at these resources suggests that in patients who are fluid restricted, 1 x 480mg/5ml ampoule co-trimoxazole may be diluted with 75mL glucose 5%.
One 480mg/5ml ampoule of IV co-trimoxazole can be diluted in 75mL glucose 5%.

The patient is prescribed 4.4g per dose which is equivalent to 4, 400mg.

Therefore, if 480mg can be diluted to 75mL, then 4, 400mg will need to be diluted to 687.5mL. This will likely be rounded up to 700mL glucose 5% in practice.

So, for QDS dosing, the patient will be having 700mL x 4 = 2.8L glucose 5% each day which may be in excess of their daily fluid allowance.  

How can you turn this information into practical advice to help the doctor? Are there any other options?

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