Breakthrough pain medication

[MPM2]

I have a question about breakthrough medication: New orders for a patient read;

‘Morphine 10mg IM/sc/po q4hours ATC’ in addition to ‘2.5-5mg IM/sc/po q1hour prn for Breakthrough Pain’.

The first routine dose of 10mg sc was given at 2000h but at 2030h the patient still complains of severe pain (vitals stable, no previous narcotic use, in severe pain from pancreatitis). Since the onset of sc Morphine may not have occurred yet should the nurse wait until 2100h to safely administer a dose of 5 mg sc prn? When is the earliest that a prn dose can be initiated in this case?

[Kdog]

wait the full hour and let the morphine work

[MPM2]

Thank you I agree. I also would tend to start with the 2.5mg an hour later then reassess effectiveness. thank you for your input.