Notes:
- This is a rough guide only; adsorption rates vary between patients and adjustments will be required
- See below for duration of effect of common narcotics
- For patients on very high doses, or other narcotics, consult pain expert, pharmacist or Lexicomp in ‘EPIC Resources’
How to calculate:
- Add up total dose taken by patient in 24-hrs
- Convert from one drug to another
- Divide total 24-hr dose by appropriate number of intervals, may need to round based on how drug supplied, and if having more pain than usual
- Add breakthrough prn doses
- Reassess orders frequently and adjust based on effects
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Example case: Person normally takes long-acting oral morphine 30 mg at home twice a day and rescue morphine 5 mg average 3 times per day > need to convert to S/C hyromorphone while NPO in hospital
Morphine = (30 x 2) + (5 x 3) = 75 mg per day oral morphine
Hydromorphone = 75/30 * 2 = 5 mg per day or 0.83 mg q4h S/C hydromorphone
Order hydromorphone 0.5 or 1 mg q4h S/C straight, depending on degree of pain, plus breakthrough prn such as hydromorphone 0.5 – 1mg S/C q4h prn
Duration of effect of common narcotics, based on drug and route
Notes:
- Duration can be prolonged by age, frailty, renal or liver dysfunction
- IV push (other than patients on APS or CADD pump ) may require enhanced monitoring; consult hospital policies
References:
- Compendium of pharmaceuticals and specialties. Opioids general monograph. Canadian Pharmacists Association. Ottawa, Canada. c 2013