An Algorithm for the Treatment of Chronic Pain with Cannabinoids

An Algorithm for the Treatmentof Chronic Pain withCannabinoidsJohn Clark MD FRCPCMedical DirectorCalgary Health Region Chronic PainCentre

Disclosure•Valeant• Bayer

Objectives• To review an algorithm for thetreatment of chronic pain withcannabinoids• Audience participation to discuss casesof intractable chronic pain wherecannabinoids might be considered

Case Discussion• 48 year old male, MVC 4 years ago• T 8 spinal fracture with incomplete spinal injury• Chronic pain– Radicular band at T 8-10 bilaterally– Left buttock and posterior thigh pain• Limited ambulation with crutches• Oxycontin 80 mg q 8hrs• Oxycodone 20 mg q 4 hrs prn (100 mg/day)• Failed TCAs and anticonvulsants

Algorithm – Step 1•Full assessment, establish diagnosis of pain•Assess psycho-social issues and risk of addiction•Determine history of previous use of illicit substances ormisuse of prescription drugs•Develop a treatment plan assuring that pharmacotherapytakes place within an overall active participatory approach•Assure that traditional approaches to chronic painmanagement have been tried or consideredPain is inadequately treatedStep 2

Algorithm – Step 2•Consider cautions and assure nocontraindications to use of cannabinoid•Discuss potential adverse effects•Consider discussing urine testing•Review and sign treatment agreementStep 3

Algorithm – Step 3Cannabinoid naïve:•Start an oral cannabinoidavailable by prescription *Previous use of cannabinoids:•Obtain a full history of previouscannabinoid use•Specific cannabinoid, dose, routeof administration•Symptoms treated and outcome•Adverse effects•Encourage oral route

Dosing• Nabilone (Cesamet®)• Dronabinol (Marinol®)• THC:CBD (Sativex®)

Dosing• Cesamet®– Initiate at 0.5 mg orally at nite time– Increase dose by 0.5 mg every 2-3 days toa maximum dose of 2 mg orally twicedaily

Dosing• Cesamet®• Dronabinol®– Initiate at 2.5 mg orally at nite time– Increase dose by 2.5 mg every 2-3 days toa maximum dose of 10 mg twice dailyorally

Dosing• Cesamet®• Dronabinol®• Sativex®– 1-2 sprays first day, then increase by 1-2sprays each day to effect/side effects– Product monograph - a maximum of 1spray every 4 hours on the first day

Has tried cannabis already…• 48 yr male with “failed low back surgerysyndrome” on fentanyl 50 ug/hr, gabapentin 800mg tid, no other medical problems, off work.Smokes 1 pack/day• Tried nabilone, no effect and made him drowsy• Tried cannabis at a friend’s house recently…”bestpain relief ever”• What do you do now?

Heavy cannabis user…• 52 yr documentary producer with 10 year historyof chronic foot pain following trauma. He claimsto have tried everything, nothing works except‘pot’. Uses 4g/day smoked and occasionally astea. No other meds. Works full-time. Examinationreveals clear tactile allodynia.• He asks you to sign medical marijuana accessforms• What do you do now?

Algorithm – Step 4 (Optional)If oral nabilone or THC trial fails or is not financiallyfeasible consider cannabis:•Discuss the fact that there are not yet clear guidelinesregarding efficacy, doses and toxicity•Raise awareness of oral and vaporized routes ofadministration•Refer patient to Health Canada website and documentsregarding cannabis product•Follow the usual clinical guideline to start low and titratedose slowly

Recommendations(Pain Research & Management)Develop a treatment plan incorporating these goals:• Reduction in pain• Increase functional abilities• Improved sleep quality• Increase quality of life• Reduction in the use of other medicationsEducate patient on:• Product nature• Potential benefits• Side effects• Discuss risk of addictionSource: Clark A.J. Cannabinoids for Pain Management. Pain Research & Management. Vol 10 Supplement A – Autumn 2005

Very heavy cannabis user…• 32 year old male, chronic low back pain withoccasional sciatica for 4 years, on fentanyl 75ug,dilaudid 4mg qid prn, ativan 1mg tid, cannabis8g/day. Off work, no surgical options…• How do you manage this patient?

Thank you.

SummaryPharmacotherapeutics and the nervoussystemCNSBrainDescending modulationAnticonvulsantsOpioidsCannabinoidsTricyclic/SNRI antidepressantsPNSPeripheralsensitizationSpinalcordAnticonvulsantsLocal anestheticsOpioidsCannabinoidsTopical analgesicsTricyclic antidepressantsCentral sensitizationAnticonvulsantsNMDA-receptor antagonistsOpioidsCannabinoidsTricyclic/SNRI antidepressantsAdapted from Nicholson BD (2005)