The Center for Palliative Care Education

Assessing and Managing Pain in HIV/AIDS

Learning objectives

• Understand the common etiologies and the diagnostic evaluation for pain in HIV/AIDS

• Know characteristics of and treatment approaches for nociceptive vs. neuropathic pain

• Describe pitfalls in treating pain in patients with substance abuse

Overview

• Case I: 35 M with HIV

–Neuropathic pain

• Case 2: 60 F with HIV and avascular necrosis

–Nociceptive pain

Case 1

• 35-year-old HIV+ man on antiretroviral therapy: –Burning, shooting, lower extremity pain–Intermittent–Not responsive to oxycodone/acetminophen (Percocet)

–Neuro exam unremarkable

Neuropathic pain

•Disordered peripheral or central nerves

•Compression, metabolic injury, ischemia, infiltration

•Peripheral, deafferentation, regional syndromes

Neuropathic pain syndromes with HIV/AIDS

• HIV neuropathy, myelopathy

• Antiretroviral medication (dideoxynucleosides)

• Chemotherapy

Additional causes of neuropathic pain

• Herpes zoster

• Diabetes

• Multiple sclerosis

• Alcoholism

• Amputation (phantom limb)

Neuropathic pain

• Pain may exceed observable injury

• Described as: burning, tingling, shooting, stabbing, electrical

• Management:

–Adjuvant medications

Pain assessment

• History: Quality, timing of pain

• Exam: Neuropathy, color, skin temperature, sensation

• Watch for: Allodynia (pain from mild stimulation, such as touching or rubbing)

• Use 0 – 10 scale

Pain management

• Switch antiretroviral medication if suspicion is high

• Don’t delay for investigations or disease treatment

• Unrelieved pain causes nervous system changes:

–Permanent damage

–Amplification of pain• Address underlying cause where possible

Evidence-based treatment of neuropathic pain

• Amitriptyline 10-75 mg po qhs:

–No placebo-controlled trials for HIV neuropathy

–+ controlled trials for diabetic neuropathy• Gabapentin (Neurontin) 100-800 tid:

–Widely used, renally cleared• Lamotrigine (Lamictal):

–200-400 mg qd

–Rare Stevens-Johnsons La Spina; Eur J Neurol 2001; 8:71-5

Simpson; Neurology 2000; 54:2115-9

Evidence-based treatment of neuropathic pain

• Topical Capsaicin (Zostrix): Often not well tolerated

• Topical Lidocaine gel

• Acupuncture: A negative trial in HIV

• Phenytoin: Occasional responders, no + controlled trials

• Mexiletine: No better than placebo (ACTG 242)

Paice; J Pain Symptom Manage 2000; 19:45-52Shlay; JAMA 1998; 280:1590-5Kieburtz; Neurology 1998; 51:1682-8

Case 1: Management

• HIV meds switched to non-ddI regimen

• Trial amitriptyline 10 mg qhs escalated to 100 mg qhs over 2 weeks

• Mild relief but still very bothersome

• Gabapentin 100 mg tid escalated to 300 mg tid over 2 weeks

• Substantial relief

Summary points: Case 1

• Neuropathic pain:

–Characteristic history

–Physical findings incl Allodynia

–Need adjuvant meds (Gabapentin)

–May also need opioids

Case 2

• 60 F HIV+ x 7 years

• Presented with aching hip pain, worse at night

• Diagnosed with avascular necrosis related to HIV

• Treated with calcium

• Started on oxycodone/acetaminophen 5mg 6x/d

• PMH alcohol abuse

Nociceptive pain

• Direct stimulation of intact nociceptors (pain receptors)

• Transmission along undamaged nerves

• Quality of pain: aching, throbbing

–Somatic: easy to localize

–Visceral: difficult to localize

Nociceptive pain

• Tissue injury apparent

• Management:

–Opioids

–Co-analgesics (NSAIDS) when possible

WHO 3-step ladder

Morphine

Hydromorphone

Methadone

Levorphanol

Fentanyl

Oxycodone

± Adjuvants

3 severe

2 moderate

A/Codeine

A/Hydrocodone

A/Oxycodone

A/Dihydrocodeine

± Adjuvants

1 mild

ASA

Acetaminophen

NSAIDs

± Adjuvants

Acetaminophen

• WHO Step 1 drug

• Site, mechanism of action unknown

• Minimal anti-inflammatory effect

• Hepatic toxicity if > 4 g / 24 hours:

–increased risk

hepatic disease, heavy alcohol use

Non-steroidal anti-inflammatory medications (NSAIDS)

• WHO Step 1: Analgesic, coanalgesic

• Inhibit cyclo-oxygenase (COX):

– Vary in COX-2 selectivity

• All have analgesic ceiling effects:

–Effective for bone, inflammatory pain

–Individual variation, serial trials

NSAIDs

• Highest incidence of adverse events

• Gastropathy:

–gastric cytoprotection

–COX-2 selective inhibitors

Short-acting opioids

• WHO Step 2:

• Short-acting opioids combined with acetaminophen

• Useful for moderate pain

• Short half-life (3-4 hours at most)

• Use limited by limitations of acetaminophen

Opioids: Routine oral dosing

• WHO Step 3:

• Use extended-release preps (morphine SR) to improve compliance, adherence

• Dose q 8, 12, or 24 h (product specific):

–Don’t crush or chew tablets

• Adjust dose q 2–4 days (i.e., once steady state reached)

Morphine dosing

• Escalate until pain is relieved

• Refrain from combining opiates

• Consider documenting a pain plan in the chart

• Low opioid dosing for chronic, non-malignant pain is an option

Opioids: Breakthrough dosing

• Use immediate-release opioids (morphine IR or elixir):

–5%–15% of 24-h dose

• Do NOT use extended-release opioids for breakthrough pain

Opioids: Essential pharmacology

• Conjugated by liver

• 90%–95% excreted in urine

• If dehydration, renal failure, severe hepatic failur:

dosing interval, dosage size

for oliguria or anuriaSTOP routine dosing of morphineuse ONLY prn

Not recommended

• Meperidine (demerol)

• Mixed agonists-antagonists (Talwin)

Opioid Side Effects

• Constipation

• Drowsiness

• Neuropsychiatric symptoms, including vivid or bad dreams

• Myoclonic jerks

• Delirium

Switching Opioids

• Consider switching if dose-limiting toxicity develops

• Use an equianalgesic chart

• Adjust the new dose for incomplete cross tolerance

–Start with about 2/3 the new calculated dose

Switching Opioids Example

• 60 mg morphine SR q12h (120 mg/24 hours)

• To convert to SR oxycodone:

–Equianalgesic dose: 120 mg/1.5=80 mg

–New dose: 2/3 x 80 = 55 mg

• Start with SR oxycodone 30 mg q 12h

Approach to managing substance abuse

• Respect patient’s report of pain

• Distinguish between tolerance and addiction (psychological dependence)

• Distinguish between active users and those in recovery

Approach to managing substance abuse

• Set clear goals for opioid therapy

-identify and discuss abuse behaviors

-use written contracts

-establish single provider

• Use a multidimensional approach:

-attention to psychosocial issues

-team approach

• Reflect on your own attitudes towards substance abuse

Is use of opioids appropriate?

• Literature for cancer pain and substance abuse suggests:

–Relapse of substance abuse occurs but is not common

–Under treatment of pain contributes to substance abuse

–Clear limits are needed

Pitfalls in treating patients with substance abuse

• Not believing pain reports

• Not prescribing adequate pain meds

• Not setting clear limits regarding prescriptions

• Clinician attitudes

• Having multiple clinicians prescribe

Case 2: Management

• Taking percocet 5mg 6x/d• Changed to long-acting oxycodone 30 mg

q12• Morphine IR 10 mg q1 hour prn

breakthrough pain• Bowel regimen: 4 glasses water, senekot

2 tabs qhs• Improved mood, activity

Summary points: Case 2

• Severe nociceptive pain often requires opioids

• Use long- and short-acting opioids together

• Treating patients with substance abuse with opioids can be successful

Contributors

Anthony Back, MD DirectorJ. Randall Curtis, MD, MPH Co-DirectorFrances Petracca, PhD EvaluatorLiz Stevens, MSW Project Manager

Visit our Website at uwpallcare.org

Copyright 2003, Center for Palliative Care Education, University of Washington

This project is funded by the Health Resources and Services Administration (HRSA) and the Robert Wood Johnson Foundation (RWJF).