3B. EPEC Pain Management
Step two: Moderate pain Tramadol Opioid combinations Acetaminophen or aspirin with •Codeine •Hydrocodone •Oxycodone Plus/minus adjuvants Dose limiting toxicity Adjuvants Primarily for neuropathic pain Antidepressants Tricyclics Venlafaxine, Duloxitene Anticonvulsants Gabapentin, pregabalin, carbamazepine Antiarrhythmics Lidocaine, mexilitene Step 3: Severe pain Pure opioids •Morphine •Hydromorphone •Oxycodone •Fentanyl •Oxymorphone •Methadone No ceiling effect Variable toxicity at very high dose Plus/minus adjuvants, non-opioids, steroids Opioids Opioids Short acting oral agents Long acting oral agents Equianalgesic dose conversions Opioid infusions PRN dosing and dose escalation Methadone Short acting oral agents Peak analgesic effect 60-90 minutes Expected duration of 3-4 hours Typical prescribed interval is Q 4-6 hours AHCPR recommends dosing interval of 3-4 hours Short acting pure opioids oral dosing Routine (not prn) schedule important for continuous pain relief PRN dose should be 10-15% of total daily dose Every 1 hour administration of single agent is safe if pain not controlled Example 1 prn dosing Oxycodone 30 mg q 4 hours 180 mg daily dose 10-15 % = 18-24 mg Oxycodone 15-30 mg Q 3 hour prn May give 30 mg in 1 hour if needed Example 2 Pseudo-prn dosing Oxycodone 30 mg q 4 hour Oxycodone 30 mg q 4 hours prn Patient uses all prn doses consistently Total daily dose 360 mg New schedule: Oxycodone 60 mg q 4 hours Oxycodone 30-60 mg q 4 hour prn Long acting oral agents Morphine Cost relative to MS 200 mg/day Morphine ER ~$40/mo Kadian, Avinza ~$680-770/mo Oxycontin ~$600/mo Hydromorphone (Exalgo) ~$3200/mo Oxymorphone (Opana/ER) ~$550/mo Methadone ~$20/mo Should be prescribed along with short acting agent for breakthrough pain Equianalgesic Dosing Equianalgesic Dosing Fred is a 58 y.o. man with pancreatic cancer diagnosed 9 months ago. Opioid regimen: Norco 10/325, 4-8 tabs per day Oxycodone extended release120 mg twice daily 4 mg dilaudid 1-2 tabs per hour for “breakthrough pain” How do you convert him to a parenteral hydromorphone infusion? Equianalgesic dosing Step 1: Calculate total daily oral morphine equivalent (OME) for each medication using equianalgesic ratios. Calculate OME of each medication Oxycodone ER 240 mg/day Oxy: MS ratio = 2:3 OME is 360 mg Calculate OME of each medication Hydrocodone 10 mg, 2 tabs QID = 80 mg Hydrocodone: MS ratio = 1:1 OME = 80 mg Calculate OME of each medication Hydromorphone 4 mg ~ 20 tabs per day Hydromorphone 80 mg/day Hydromorphone: MS ratio = 1:4 OME is 320 mg Calculate total daily OME Oxycodone Hydrocodone Hydromorphone Total OME 360 mg 80 mg 320 mg 760 mg Equianalgesic dosing Equianalgesic tables and calculators vary Individual variation and incomplete cross tolerance between opioids exists Tables and calculators are only guidelines 30-50% decrease in calculated dose is prudent Equianalgesic dosing Step 2: Reduce calculated dose by 1/3 to 1/2 based on patient variability 760 mg x 2/3 ≈ 500 mg po morphine Step 3: Convert to equivalent parenteral morphine dose 500 mg po morphine * 1/3 ≈ 167 mg iv morphine 167 mg iv morphine per day/24 hours ≈ 7 mg iv morphine/hour Step 4: Calculate equianalgesic dose of i.v. hydromorphone 7 mg iv morphine/hour*1.5/10 ≈ 1 mg iv hydromorphone/hour Or use a calculator You order dilaudid 1 mg iv per hour continuous 2 hours later the nurse calls to tell you is pain is no better. What happened? What do you do? Step 5: Add loading dose equal to 1-2 times the hourly dose Time to steady state takes 3-5 half lives or 12-20 hours for most opioid infusions Opioid infusions PRN dosing Fred is given 2 mg iv hydromorphone followed by 1 mg/hour continuous infusion What is the appropriate PRN dose? PRN should be 50-150% hourly rate 1 mg hydromorphone PRN How often? PRN dosing interval is based on time to Cmax
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