For this question you are changing opioid but keeping the same route so you start a new opioid at 50-75% of the calculated equianalgesic dose (or dose reduce by 25-50%).
First, calculate the 24-hour current dose: 10 x 6 doses in 24 hours = 60 mg PO Oxycodone/24 hours. This total amount needs to be converted to PO Hydromorphone in 24 hours then the total divided into 6 doses (for the Q4hr use). The equianalgesic ratio of PO Oxycodone to PO Hydromorphone ranges depending upon which conversion table is used. Calculations with both commonly used conversions are shown below:
1) Use the equianalgesic ratio of PO Oxycodone to PO Hydromorphone:
20mg PO Oxycodone = 7.5 mg PO Hydromorphone
Calculate new dose using ratios: (60mg x 7.5)/20 = 22.5mg of PO Hydromorphone in 24 hours
Reduce dose 25-50% for cross-tolerance =1.25-16.875 mg in 24 hours
11.25mg/6 = 1.875mg PO Hydromorphone Q4hr (reduced by 50%)
16.875/6 = 2.81mg PO Hydromorphone Q4hr (reduced by 25%)
Therefore, 2mg PO Q4hr is the best answer.
2) Use the equianalgesic ratio of PO Oxycodone to PO Hydromorphone:
30mg PO Oxycodone = 7.5mg PO Hydromorphone
The calculation would be:
(60mg x 7.5)/30 = 15mg of PO Hydromorphone in 24 hours
Reduce dose 50% for cross-tolerance: 7.5-11.25mg in 24 hours
7.5mg/6 = 1.25mg PO Hydromorphone Q4hr (reduced by 50%)
11.25mg/6 = 1.875mg PO Hydromorphone Q4hr (reduced by 25%)
Therefore, of the above answers, 2mg PO Q4hr remains the best answer.
For this question you are changing opioid but keeping the same route so you start a new opioid at 50-75% of the calculated equianalgesic dose (or dose reduce by 25-50%).
First, calculate the 24-hour current dose: 10 x 6 doses in 24 hours = 60 mg PO Oxycodone/24 hours. This total amount needs to be converted to PO Hydromorphone in 24 hours then the total divided into 6 doses (for the Q4hr use). The equianalgesic ratio of PO Oxycodone to PO Hydromorphone ranges depending upon which conversion table is used. Calculations with both commonly used conversions are shown below:
1) Use the equianalgesic ratio of PO Oxycodone to PO Hydromorphone:
20mg PO Oxycodone = 7.5 mg PO Hydromorphone
Calculate new dose using ratios: (60mg x 7.5)/20 = 22.5mg of PO Hydromorphone in 24 hours
Reduce dose 25-50% for cross-tolerance =1.25-16.875 mg in 24 hours
11.25mg/6 = 1.875mg PO Hydromorphone Q4hr (reduced by 50%)
16.875/6 = 2.81mg PO Hydromorphone Q4hr (reduced by 25%)
Therefore, 2mg PO Q4hr is the best answer.
2) Use the equianalgesic ratio of PO Oxycodone to PO Hydromorphone:
30mg PO Oxycodone = 7.5mg PO Hydromorphone
The calculation would be:
(60mg x 7.5)/30 = 15mg of PO Hydromorphone in 24 hours
Reduce dose 50% for cross-tolerance: 7.5-11.25mg in 24 hours
7.5mg/6 = 1.25mg PO Hydromorphone Q4hr (reduced by 50%)
11.25mg/6 = 1.875mg PO Hydromorphone Q4hr (reduced by 25%)
Therefore, of the above answers, 2mg PO Q4hr remains the best answer.