Jack Smith is a terminally ill lung cancer patient. Jack Smith's current
pain medication is Morphine sulfate sustained release 45mg every 12 hours.
During a clinic visit, Mrs. Smith complains that she has noticed that her
husband has developed muscle twitching ever since his Morphine sulfate sustained
release was increased to 45mg every 12 hours. You review Mr. Smith's recent
chemistry panel and note that his creatinine is elevated at 2.4. Please
convert the transdermal fentanyl into an equianalgesic dose of long acting
First determine total 24 hour dose of current drug.
The total dose is the product of the unit dose in milligrams
and the frequency of administration in 24 hours.
In this case:
Unit dose = 45mg
Frequency of administration = 2 times in 24 hours
Therefore total dose = Unit dose x frequency = 45 x 2= 90mg
Patient is currently on 90mg of Morphine sulphate.
Convert total 24 hour dose of current drug to equianalgesic dose
of ORAL morphine.
Current drug in this case is Morphine sulfate.
4 hour equianalgesic dose = 90mg of morphine sulfate.
Convert the calculated 24 hour equianalgesic dose of oral morphine
to the 24 hour equianalgesic dose of the new opioid.
Oxycodone is the preferred drug in this case as it is renally safer
than morphine. Oxycodone is thought to be 1.5 times stronger than
Therefore, Morphine sulfate 90mg is equianalgesic to oxycodone 60mg
24 hour equianalgesic dose of the new opioid (oxycodone) = 60mg
Divide the 24 hour dose of the equianalgesic dose of the new opioid
to determine the unit doses and frequency.
Similar to morphine, oxycodone is available in a sustained acting
preparation Oxycodone (OxyContin™) that can be dosed every
12 hours. In this case Oxycodone 60mg in 24 hours can be divided
into a unit dose of 30mg to be given every 12 hours.
Final order for basal analgesic should read:
Oxycodone sustained release every 12 hours for chronic pain.