Palliative Care Summer Institute Aspects of Managing Severe Pain
Aug 14, 2015
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Opioid RotationOpioid Neurotoxicity
Opioid Equianalgesic DosingAdjunct medications
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Opioid Rotation Indications
Poor analgesia despite increasing dosesAdverse effects are intolerable, toxicityNeed different route of administrationChange in clinical status (drug abuse?,malabsorption)
Financial/drug shortage considerations
-Fine and Portenoy: “Best Practices for Opioid Rotation JPSM 9 2009
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Opioid Rotation
• 30% pts need new route (severe nausea, mucositis)
• Controlled Pain: reduce dose for incomplete cross tolerance
• Uncontrolled pain = use equianalgesic dose• Toxicity: Lower dose, treat side effects, use
adjuvants• Prevent toxicity by:• Using opioids cautiously renal or hepatic
dysfunction• Intestinal colic Rx: Decadron,
Glycopyrrolate, Octreotide
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Opioid Rotation Guidelines
Calculate Equianalgesic Dose using tableSevere pain = use equianalgesic doseMod pain or other route-lower this 25-50% (incomplete cross tolerance)
Double check calculations (measure twice, cut once)
Methadone-non linear conversionReassess frequently
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Opioid Equianalgesic DosingEQUIANALGESIC DOSES OF OPIOIDS
Analgesic Oral/Rectal mg = IV/SQ mg
Morphine 30 10
Hydromorphone 7.5 1.5
Oxycodone 20 ---
Hydrocodone 30 ---
Codeine 200 130
Fentanyl --- 0.1mg = 100mcg
Methadone see ratios below 1/2 Oral=IV Dose
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Opioid Rotation GuidelinesMETHADONE CONVERSION RATIOS Oral Morphine
Daily Dose MS:MEExamples
MSmg:MEmg
0-100 3:1 100:33
101-300 5:1 300:60
301-600 10:1 600:60
601-800 12:1 800:60
>1000 20:1 1200:60
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Opioid Neurotoxicity-Dx & Assessment
Occurs with escalating doses (3 Glucuronide metabolites):
• Frequency of myoclonic jerks• Hyperalgesia (allodynia)• Delirium, hallucinations, seizuresCommon risk factors: • Dehydration, • Drugs: (haldol, phenothiazines)• Renal, hepatic dysfunction, Mg+
+, Na+
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Opioid Neurotoxicity-TreatmentObservation
Opioid dose reductionOpioid rotation
AdjuvantsBenzodiazepines
Hydration
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Morphine : Fentanyl
Morphine Oral mg
Morphine IV mg
Fentanyl IV mcg/hr
30 10 100*
720 240 2400
100 30 50mcg/hr patch**
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IV Morphine : Fentanyl patch
• 1st 6 hrs: bolus IV morphine• 2nd 6hrs MS infusion at ½ the
equianalgesic dose (100mcg fentanyl=MS 5mg/hr)
• >12 hrs start full conversion (10mg/hr)
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Methadone
NMDA receptor antagonist, mu opioid agonistExcellent in opioid tolerance, neuropathic painLong half lifeHigh oral bioavailabilityNo active metabolitesInexpensiveProlonged QT concerns, so:• Start low, go slow• Limit to <100mg/day
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Ketamine
NMDA receptor antagonistAnesthetic, sedative, powerful analgesicSpares opioids-decrease opioids 25% initially, 25-50% @6-12 hrs and as needed until equilibriumBenzodiazepine helpsPsychomimetic side effectsConsider adding@ 100mg/hr morphine
1000mcg/hr fentanylInitiate 80 mcg/kg/hr IV/SQContinuous infusion 80-600 mcg/kg/hr
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Lidocaine
Sodium channel blockerGood for neuropathic painIV/SQ infusion: Bolus 1-2mg/kg, then 0.2-1mg/kg/hrTitrate to effectDecrease opioid dose 50% every 6-12 hrs thereafterMay have twitching at high doses
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Other Adjuncts
GabapentinBisphonphonatesAntidepressantsAnticonvulsantsMuscle relaxantsLocal anestheticsCannabinoidsTopical agents
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Interventional Procedures
Trigger point injectionsNerve blocksEpidural and Intrathecal cathetersEBUS celiac plexus blocks