Prof. Krishna Boddu. MBBS, MD, DNB, FANZCA, MMEd MBBS, MD, DNB, FANZCA, MMEd University of Texas Health Sciences at Houston, Texas, USA University of Western Australia, Perth, Australia Director, Regional Anaesthesia, Royal Perth Hospital, Perth, Australia 1

1. Patient on Oral Pain medication – Now NPO 2. Post-Op patient On IV meds. Now on regular diet. 3. Regional (Epidural/ nerve blocks) to other mode 4. Drug interaction Eg. Started on Refampin 5. Drug diversion 2 InterventionalIV, IM, Sub QPO/ NG TubeOther PAIN Activity NPO Status Tolerance

3 Details of all the Analgesics in use Names of the drugs Routes of administr Dose, Freq, 24h use Pharmacodynamics Information from Patient and Charts Information from Text Books Bioavailability, Max dose, Equipotency & interactions Onset, duration of action & peak effect Wash in & wash out curves

4 How long the patient is on these? Convert 24 hour dose to IV MSO4 Equivalent OpioidsNon-Opioids Estimated Opioid Equivalence available for some Local Anesthetic based analgesia poses challenges

Scenario 1: For back pain, for several months patient is on -100mg of MSContin PO Q8h & -30mg MSIR Q 4h PRN (uses approx 90mg/day) -100mg Pregabalin Q8h for neuropathic pain 5 How to transition to IV PCA? What are the steps? 390mg PO MSO4 in 24h (Actual) = 130mg IV MSO4 in 24h (Estimated) Per hour IV Morphine use= 5.41mg (Estimated) Will pt be happy with 1mg dose with LOI 5 min? (She could get 12mg/h = 288mg MSO4 IV in 24h) NO Might be OK During the Day For Sure She will have Disturbed Sleep For Sure She will wake up with Severe Pain WHY?

6 You Convince Patient That The Amount of Medication Available For Her Is Way More Than She Was Taking At Home to Cover Her Pain. Now, Patient Requests for Sleeping Pills. Just because you are giving IV Pain Medication that too plenty available does not mean that you will be able to provide better pain control 1-2mg/h MSO4 IV basal on PCA would be better than introducing sleeping pills. What About Pregabalin?

Scenario 2 (Surgeon’s request) : Post op pain pt on IV PCA Hydromorphone & history of heroin abuse ready for transition to PO pain meds. 24 hour consumption of HM is 30mg. 7 How to transition to PO meds? What are the steps? 30mg IV Hydromorphone in 24h (Actual) = 150mg IV MSO4 in 24h (Estimated) (based on equi-potency) 600mg PO MSO4 in 24h (Estimated) (based on BA) Will you be comfortable to give 600mg PO Morphine to a pt with history of drug abuse? NO Will you let the pt suffer? What will be your concerns? WHY? How to handle this situation?

We can not let patient suffer with pain irrespective of his social, racial, criminal backgrounds. 8 Our main concern: How to transition IV to PO and wean off this patient from PO? Who will priscribe large opioid doses at the time of discharge? Follow the rules of managing opioid tolerant patient. 1.Optimize non-opioid analgesics + Tramadol 2.Start on alpha 2 agonists clonidine (PO/ TD) 3.NMDA modulators (Ketamine PO/ IV), 4.Lidoderm 5% patch 5.Oxycodone ER with Nalaxone PO 60mg Q mg Oxynorm PRN Q4h

Rationale for Oxycontin & Oxynorm doses mg IV MSO4= 180 mg Oxycodone Give 60% as long acting 60mg Q8h = 120mg70mg Q8h = 210mg Oxycodone Bioavailability 80% 180mg – 120mg = 60mg 60mg/6 = 10 mg (Order mg PRN Q 4h) Remaining dose as PRN in 6 divided doses Q4h Books say 1.2mg – 2mg Oxycodone = 1mg IV MSO4 150 mg IV MSO4= 300 mg Oxycodone Oxycodone Bioavailability 50% 300g – 210 mg = 90mg 90mg/6 = 15 mg (Order mg PRN Q 4h)

3. Transition from Epidural analgesia to IV/PO Epidural Solution Opioid + Local Anesthetic Local Anesthetic Non-Lipophilic Opioids 1000 mcg IV= 100 mcg Epidural= 10 mcg Spinal Difficult to convert to Opioid Equivalence, so use PRN Opioid Medication to cover Lipophilic Opioids 1000 mcg IV= 500 mcg Epidural= 250 mcg Spinal Epidural Solution 8ml/h (LA+ 5mcg Hydromorphone/ml Epidural 50 mcg/h (1200 mcg/day) = mcg/day IV Per day 12 mg IV HM = 55 mg IV MSO4 This can be easily covered with PO 400 mg Tramadol, 4 g Paracetamol, NSAIDS per day My Transition Orders Stop Epidural after giving first dose of PO Oxycodone 10mg Paracetamol 1g Q6h (PO/ IV) Tramadol 100 mg Q 6h (PO/ IV) NSAID (Celebrex 200 mg BD) / Parecoxib 40 mg Q 8 IV PRN Oxycodone mg Q 3h (Mild-moderate-Severe) If Transition Is Smooth, After 4 h Remove Epidural Catheter

4. Transition from Nerve Catheter to IV/PO Local Anesthetic Difficult to convert to Opioid Equivalence, so use PRN Opioid Medication to cover My Transition Orders Stop infusion after giving first dose of PO Oxycodone 20mg Paracetamol 1g Q6h (PO/ IV) Tramadol 100 mg Q 6h (PO/ IV) NSAID (Celebrex 200 mg BD) / Parecoxib 40 mg Q 8 IV PRN Oxycodone mg Q 3h (Mild-moderate-Severe) If Transition Is Smooth, After 4 h Remove Nerve Catheter Remember that it takes only 1-4 hours for block to disappear after stopping infusion

5. Drug interaction Eg. Refampin Complete loss of analgesia possible when pt started on Refampin With in a day after starting Refampin Oxymorphone is least influenced by enzyme induction How to avoid this ? 1.In paper form: APS signs to let us know 2.In Electronic Orders: APS as pain medication and build drug interaction list of your choice Do we need to let patient suffer with pain before transition to other? Close and through followup of APS is required to implement this Consider optimal non-opioid anagesics + Regional Analgesia BE AWARE OF ENZYME INHIBITORS & INDUCERS

Pain Questions First 48h postop or any pain at rest or pain all the time Pain on activity Give meds ATC (basal on PCA, PCEA) Give PRN medication (PRN on PCA, PCEA) Pain not down to satisfactory level Pain decreased to satisfactory level Relief not lasting long enough Increase PRN dose Requiring frequent PRN > 4 times/ day. Decrease dose interval Consider adjusting ATC dose to keep 60% of 24 hr requirement as ATC Analgesia fine tuning Only on waking up in the morning Night time basal or dose

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