Question

the patient on the telemetry unit is having chest pain and has an order for nitroglycerin at 10 mcg/min. How many milliters per hour should the IV pump be programmed for?

Answer 1

Usually Nitro-glycerine is available as 10 mL Single Dose Vial (5 mg/mL Injection USP). It is always given after dilution.

Total dose available in one vial of 10 ml and strength is 5 mg per ml

= 5mg X 10 ml

= 50 mg

On converting ordered dose of 10 mcg per minute to mg per hour

1 mg= 1000 mcg

Ordered dose is 10 mcg / minute

On converting this dose in to mg/ hr

= (10/1000)* 60

= 0.6 mg per hour

Nitroglycerin is always used after dilution.Dilutents used are 5% Dextrose Injection or 0.9% Sodium Chloride Injection.

A common dilution used is 50 mg of nitro glycerine in 250 mL of 5% Dextrose Injection or 0.9% Sodium Chloride Injection. The solution is stable for 48 hours at room temperature.

Using this recommendation after dilatation reconstituted solution will have 50 mg of nitro-glycerine in 250 ml of either dextrose injection or sodium chloride Injection.

Now according to formula for calculation of IV dosage

Dose ordered - X Volume available = Dose Dose available

On putting values for hourly calculation

(0.6 mg per hour/ 50 mg) X 250 ml

= 3 ml per hour

Hence pump should be programmed to deliver a dose of 3 ml per hour.

Other considerations

· Because of the problem of nitro-glycerine absorption by polyvinyl chloride (PVC) tubing, Nitro-glycerine Injection should be used with the least absorptive infusion tubing (non-PVC tubing).

· The dosage for nitro-glycerine should carefully titrated and patient should be carefully monitored for response.

· Severe hypotension and shock may occur with even small doses of nitroglycerinis drug should therefore be used with caution in patients who may be volume depleted or who, for whatever reason, are already hypotensive