Pain in Palliative Care: Role of Methadone Flashcards
Long-acting Agents
Available
◦ Codeine
◦ Morphine
◦ Hydromorphone
◦ Oxycodone
◦ Tramadol (various
formulations)
Dosed q12h or daily
◦ Some claim needed more
frequently
◦ Avoid if impaired
absorption from gut
Should not be used when titrating doses
Use immediate release until pain is stabilized
May revert to longacting once stable, if new opioid has longacting agent available
Methadone is dosed q8h for pain
Conversion
◦ Total dose of immediate acting opioid, divided by # doses/day.
◦ Example
Hydromorphone 4 mg po
q4h atc (24 mg) converts to
Hydromorphone contin®
12 mg po q12h
Kadian
Morphine 24 hr
release ◦ Addictions > pain
When dispensing
long
-acting morphine
be sure to select the
correct product
NOT interchangeable
with MS Contin® or M-Eslon ® (12-hr
release)
Injectable
Morphine,
hydromorphone, fentanyl
available
Different concentrations
(select most appropriate)
Methadone & oxycodone
must be manufactured
◦ Compounding pharmacies
with suitable equipment
Use 50% of dose when
converting to
parenteral routes
◦ Dose
5 mg (0.5 mL)
IM/IV/subcut q4h &
2.5 mg (0.25mL)q1h prn
opioid rotation
Calculate total daily dose including
breakthrough doses taken
Use table to determine equi-analgesic dose
Decease by 20 – 30% (incomplete crosstolerance)
Calculate regular dose (based on q4h or q8h)
10% total daily dose q1h prn for BTA
F/U daily to monitor pain & toxicities
Care in cancer patients
◦ Underestimation can
induce a pain crisis or
opioid withdrawal
◦ Overestimation can lead
to toxicity
◦ May need to titrate
dose post-conversion
◦ Use ONE opioid if
possible
Easier to identify sideeffects
ethadone rotation
Different methods used (clinically based)
◦ Edmonton method as inpatient (4 days)
◦ Can be done as outpatient (slowly)
Initiated by palliative specialist (with expertise)
◦ Variable kinetics
Conversion ratio is dose dependent
◦ oMEDD < 1000 mg/day use 10:1
◦ oMEDD :1000-3000 mg/day use 20:1*
◦ oMEDD :3000- 10 000mg/day use 30:1*
◦ oMEDD > 10 000 mg/day use 50:1*
* Based on clinical expertise. Equation not validated yet.
Divided into q8h dosing
Hydromorphone dose has
escalated
◦ 6 mg po q4h atc
◦ 3 mg po q1h prn pain/dyspnea
◦ Taking 6 BTA daily
Calculate oMEDD:
◦ ATC dose = 6mg, 6 times daily = 36mg
◦ PRN dose = 3 mg x 6 doses = 18 mg
◦ Total hydromorphone daily = 54mg
◦ conversion to morphine (5:1)
◦ oMEDD = 270 mg
Calculate target dose of methadone
◦ oMEDD < 1000 mg: use 10: 1 ratio
◦ = 27 mg methadone
Reduce by 20 – 30 % for incomplete cross-tolerance
◦ 27 x 75% = 20.25 mg/day (↓ 25%)
Calculating for q8h dose = 7 mg po q8h (21mg)
◦ Rounding to convenient dose
Calculate the breakthrough dose for day 4
◦ = 10% of total daily dose (20mg)
◦ = 2 mg po q1h prn pain/dyspnea
converting jack to oxycodone
Do not need to take 4 days
◦ If not converting to methadone
oMEDD = 270 mg
75% (incomplete cross-tolerance) = 202.5 mg
Using 1.5 ratio morph: oxy = 135 mg
22.33 mg q4h atc
Round up to 22.5 mg (can use 5 mg tabs)
12.5 mg po q1h prn pain/dyspnea
routes of admin methadone
Methadone/oxycodone
3 days fridge unless
sterility tested.
Commercially
available
◦ Tablets (oral)
◦ Liquid (Feeding tube)
Liquid not usually
given orally to
cancer patients.
◦ May taste unpleasant
Methadose® cherry
◦ May induce nausea
Manufactured in
hospital or
compounding
pharmacies
◦ Suppositories
◦ Injectable
Conversions
◦ PO: FT = 1:1
◦ PO: PR = 1:1
◦ PO: SC = 1: 0.5-0.8
subq admin
Methadone injection made my compounding
pharmacies & sterility tested
SC methadone must be administered
intermittently q8h (not continuous infusion)
Keep a SC site dedicated to methadone
While administering dose flush with normal
saline at 60-75 mL/h
Flush with 30 mL saline post dose to perfuse
tissue and avoid irritation
Rotate sites as necessary
