 |
 |
Note: The following table is adapted from Principles of Analgesic Use in the Treatment of Acute Pain and Cancer Pain 4th Ed. Chicago: American Pain Society, 1999. Note that morphine is the reference drug against which other opioids are compared.
Equianalgesic Doses of Opioid Analgesics
|
ORAL/RECTAL DOSE
|
ANALGESIC
|
PARENTERAL DOSE (MG)
|
|
30-60
|
Morphine
|
10
|
|
7.5-8
|
Hydromorphone (Dilaudid)
|
1.5
|
|
20
|
Oxycodone
|
(not available)
|
|
see below
|
Methadone
|
see below
|
|
4 acute, 1 chronic
|
Levorphanol (Levo-Dromoran)
|
2 acute, 1 chronic
|
|
(not available)
|
Fentanyl
|
0.1 (100mcg)
|
|
see below
|
Fentanyl (transdermal)
|
see below
|
|
300
|
Meperidine (not recommended)
|
75
|
|
200
|
Codeine (not recommended)
|
120
|
|
20
|
Hydrocodone
|
(not available)
|
|
Not recommended
|
Propoxyphene
|
(not available)
|
Morphine PO:IV = 60:10 for opioid naive patient, 30:10
for others.
Oxycodone - may be used chronically for severe pain only when it is not
combined with aspirin or acetaminophen-see precautions for Hydrocodone.
Methadone - is an excellent choice for opioid rotation. Where other
opioids can be converted based on a fixed ratio, the starting methadone dose
decreases proportionately as the dose of the previous drug increases. Put
another way, the morphine:methadone ratio changes as the morphine dose increases.
Calculate the equianalgesic dose using the following method, then reduce the
calculated dose by 25-50% to determine the starting dose. The following table
shows PO morphine:PO methadone.
| <90 mg MS |
4:1
|
| 91-300 mg MS |
8:1
|
| 301-600 mg MS |
12:1
|
Levorphanol - has long half life and begins to accumulate
on days 2-3.
Transdermal Fentanyl (fentanyl patch) - 50 mcg/h patch = Morphine 100mg
PO/24 h = 16 mg PO q4h = 1.4 mg/h IV.
Meperidine - should be used only for very short term moderate pain. It
is very short acting (dose must be repeated at least every 3 hours) and rapidly
accumulates neurotoxic metabolites.
Codeine - dosing is limited by the potential toxicities of the acetaminophen
with which it is often combined. Side effects are more problematic than those
for equianalgesic doses of other opioids. It should be used for short term
moderate pain only. Unlike most other opioids, analgesia does not increase
with doses greater than 200 mg ("ceiling dose").
Propoxyphene - is a weak opioid that rapidly accumulates neurotoxic
metabolites and should not be used for severe or chronic pain.
Hydrocodone - dosing is limited by the potential toxicities of the
acetaminophen or ibuprofen with which it is combined. It should be used for
short term moderate pain only.
An equianalgesic table such as this one can be used on the horizontal axis to switch routes of administration and on the vertical axis to switch between opioids.