Medications for low back pain

What  Medica+on  for    Low  Back  Pain?  

Dr  Brendan  Moore  Pain  Medicine  Specialist  Physician  

 Adjunct  Associate  Professor,  University  of  Queensland  Honorary  Associate  Professor,  University  of  Hong  Kong  

RaAonal  use  of  analgesia  in  nocicepAve  pain1  

 First line 1. Non-opioid analgesics

– Paracetamol or NSAID 2. Combination therapy

– Use non-opioids first – paracetamol + NSAID – COX-2 inhibitors

3. If pain persists or involves neuropathic component – Adjuvant – TCA or anticonvulsant – Tramadol, Tapentadol

4. Strong opioids 2.    

“SciaAca”:  mixed  pain  state  with  several  possible  pathological  mechanisms  

Baron  R,  Binder  A.  Orthopade  2004;  33:  568-­‐75.      

Central  sensiAsaAon  

Disc  C  fibre  

C  fibre  A  fibre  

NocicepAve  component:  SprouAng  from  C-­‐fibres  into  the  disc  Neuropathic  component  I:  Damage  to  a  branch  of  the  C    fibre  due  to  compression  and  inflammatory  mediators  

Neuropathic  component  II:    Compression  of  nerve  root  

Neuropathic  component  III:    Damage  to  nerve  root  by    inflammatory  mediators  

Analgesic  targets1  

 Pharmacotherapy  •  Non-­‐opioid  analgesics  

•  Adjuvant  analgesics  •  Opioid  analgesics  

slide16askin(1).wmv  

First  line  treatment  in  nocicepAve  pain:    Non-­‐opioid  analgesics    

Paracetamol  NSAIDs  

•  Drug  of  choice  in  mild  to  moderate  pain  •  EffecAve  analgesic  and  anApyreAc  

Benefits  .  Familiar  .  High  efficacy  profile  for  mild  nocicepAve  pain  .  Minimal  side  effects  .  Can  be  used  as  adjunct  therapy  with  NSAIDs  and  op  

First line analgesia – paracetamol

•  Give  adequate  doses  •  4  gm  per  day  in  divided  doses  •  Controlled  release  preparaAons  

may  improve  compliance  •  665  mg  X  2  three  Ames  a  day  •  Paracetamol  when  combined  with  

an  NSAID  allows  a  lower  dose  of  the  NSAID    

Paracetamol – dosing

Reactions involved in paracetamol metabolism3

Non-steroidal anti-inflammatory drugs (NSAIDs) – biochemical pathway

•  Analgesic  and  anA-­‐inflammatory  

•  AnApyreAc  acAon  

•  Non-­‐selecAve  cyclo-­‐oxygenase  inhibiAon  of  COX-­‐1    and  COX-­‐2  

•  Inhibit  prostaglandin  synthesis  in  peripheral  Assues,    nerves  and  the  CNS  

NSAIDs  

NSAIDs  are  valuable  analgesics  inappropriately  selected  paAents    Consider  whether  the  potenAal  benefits  of  adding  an  NSAID  outweigh  the  potenAal  harms    

NSAIDs (continued)

Prefer  NSAIDs  with  a  low  risk  of  gastrointesAnal  adverse  effects      Assess  cardiovascular  and  renal  risk  before  prescribing  an  NSAID    Monitor  for  renal  impairment  and  symptoms  of  heart  failure  in  paAents  at  risk    Use  NSAIDs  at  the  lowest  effecAve  dose  for  the  shortest  possible  duraAon    

NSAIDs (continued)

NSAIDs (continued)

Pooled relative risk of serious upper GI complications with NSAIDs versus ibuprofen

Cardiovascular  risk  

–  Increased  BP  –  High  cholesterol  –  LVH  

Diabetes  Renal  impairment  MedicaAons  

–  ACE  inhibitors  especially  with  a  diureAc  

Cardiovascular risk assessment

References: 1. National Prescribing Service, 2008. 2. The Australian COX-2 Specific Inhibitor Prescribing Group, 2002.

•  Volume  depleAon  

•  MedicaAons    •  –  DiureAcs  •  –  ACE  inhibitors  

•  GFR  <60  mL/min  

Renal impairment

•  Pre-­‐exisAng  renal  impairment  

•  Hypovolaemia,  hypotension  

•  Serious  cardiovascular  complicaAons  have  been  reported  with  the  use  of  COX-­‐2  

•  InteracAons  with  nephrotoxic  agents  and  ACE  inhibitors  

COX-2 inhibitors – contraindications

Second  line  treatments    in  nocicepAve  pain  

 CombinaAon  therapy:  Tramadol,  Tapentadol  Tricyclic  anAdepressants  

Second  line  treatment:  •  CombinaAon  therapy  improves  efficacy  of  paracetamol  and  

NSAIDs  vs  paracetamol  alone1,2  Many  pa+ents  will  self-­‐prescribe  codeine  as  a  second  line  treatment3  

•  Seen  as  a  ‘stronger’  analgesic,  paAents  may  not  fully  understand  the  risk  of  dependence  and  side  effects    

•  It  is  important  to  advise  paAents  against  ongoing  use  for  chronic  pain  

•  Consider  TCAs,  tapentadol  or  tramadol  if  mixed  nocicepAve/  neuropathic  pain  is  suspected  or  if  sleep  disturbance  is  prominent  

Second line treatments

Neuropathic  pain  analgesic  pathways  

2nd line treatment2 3rd line treatment2

Neuropathic pain treatment pathways

Multidimensional approach Coordinated assessment and treatment

GP + psychologist + physiotherapist

Early intervention, diagnosis and treatment result in improved patient outcomes1

References: 1. Nicholas, 2004. 2. Allen, 2005.

1st line treatment

Tricyclic antidepressants

or Antiepileptic (1 drug only)

2nd line treatment2 3rd line treatment2

Tricyclic antidepressants

+ Antiepileptic

(combination)

Strong opioids. Alone or in combination with

tricyclic antidepressants +/-

Antiepileptic +/-

Invasive procedures Dorsal column stimulator

First  line  treatment    (ini+al  monotherapy  trial)    Tricyclic  anAdepressant        OR      

AnAepilepAc  

First line analgesia – neuropathic pain1

Tricyclic  an+depressants  (TCAs)  

•  EffecAve  therapy  for  neuropathic  pain1  

•  Amitriptyline  –  iniAal  low  dose  5–10  mg  nocte2  

•  Side  effects:  sedaAon  and  anAcholinergic  effects2  

First line analgesia – neuropathic pain1

Selec+ve  Noradrenalin  Reuptake  Inhibitors  (SNRIs)    Venlafaxine  –  Level  II  evidence,  inhibits  the  reuptake  of  both  serotonin  and  noradrenaline  DuloxeAne    

Side  effects  include  (but  are  not  limited  to)  agitaAon,  insomnia  or  somnolence,  gastrointesAnal  distress  and  inhibiAon  of  sexual  funcAoning    

Second line treatments Adjuvant therapy in neuropathic pain

Gabapen+noids      Have  become  the  treatment  of  choice1    

EffecAve  treatment  for:  –    Painful  diabeAc  neuropathy,  postherpeAc    neuralgia,  spinal  

 cord  injury  pain  and  HIV-­‐  related  neuropathy    PharmacokeneAc  advantages

Anticonvulsants in chronic pain

References: 1. Backonja, 2002. 2. Gilron & Flatters, 2006.

Modulates  neurotransmimer  release  e.g.  

Pregabalin  binding  to  alpha2-­‐delta  

Voltage  gated  Ca2+channel  

NeurotransmiQer    tTransporter  

Noradrenaline  

Glutamate  

Substance  P  

Presynap+c  

α2δ  subunit  

Postsynap+c  

NeurotransmiQer  binding  site  

Pregabalin  binds  to  the  α2δ  subunit  of    voltage-­‐gated  Ca2+  channels  in  the  brain  

Benzodiazepines1    Clonazepam  (0.5–1  mg  bd)  has  been  successfully  used  to  treat    phantom  limb  pain    Side  effects  include  (but  are  not  limited  to)  dizziness,  sedaAon,    depression    Tolerance  and  dependence    

Alpha2  agonists2    Clonidine  produces  analgesia  at  the  spinal  level  through    sAmulaAon  of  cholinergic  interneurons    Side  effects  include  sedaAon  and  hypotension  

Other adjuvant therapies for neuropathic pain

Tramadol    Tapentadol  

Opioid prescribing: dose limits and considerations  

Suggested maximum opioid dose

•  Consult a Pain Medicine Specialist if higher doses considered necessary

1. Hunter Integrated Pain Service. Opioid use in persistent pain. November 2010

Drug Maximum dose for GP prescription

Morphine 120mg daily Oxycodone 80mg daily Hydromorphone 24 mg daily Methadone 40mg daily Fentanyl transdermal patch 25 mcg/hr applied every 3 days Buprenorphine transdermal patch 40 mcg/hr applied weekly Tramadol 400 mg daily

Dose conversion

Morphine equivalence to

Ratio morphine : named opioid

Examples of equivalent doses

Codeine 1:6 Morphine 10 mg Codeine 60 mg Oxycodone 1.5:1 Morphine 60 mg Oxycodone 40 mg Hydromorphone 5:1 Morphine 60 mg Hydromorphone 12 mg

Tramadol 1:5 Morphine 10 mg Tramadol 50 mg Fentanyl Morphine 90 mg Fentanyl 25 mcg/h Buprenorphine 75:1 Morphine 9 mg Buprenorphine 5 mcg/h

Methadone 3:1 Morphine 60 mg Methadone 20 mg

1. Hunter Integrated Pain Service. Opioid use in persistent pain. November 2010

Opioid trial guidelines

•  Commence trial with low dose sustained-release opioid

Use a lower dose and titrate slowly in patients

who are:

•  Elderly •  Taking other CNS depressants •  Opioid naïve •  Have severe hepatic or renal dysfunction

1.  Graziotti & Goucke, 1997.

Review of opioid trial

•  Discuss progress and outcomes

•  Functional goals achieved? •  Medication used responsibly? •  Discuss risks / benefits of continued therapy •  Assess 4 ‘A’s1

–  Analgesia –  Activity –  Adverse effects –  Aberrant drug behaviours

1. Gourlay & Heit, 2005.

Federal requirements

PBS prescription Restricted benefit •  Chronic severe disabling pain not responding to non-

narcotic analgesics (treatment <12 months) •  If treatment required beyond 12 months, patient must be

reviewed by a second medical practitioner

•  Authority required when prescribing increased quantities of opioid and/or repeats –  By phone – 1 month’s supply with no repeats –  In writing – 1 month’s supply with 2 repeats

•  Short term supply can be prescribed without an authority

Department of Health and Ageing, 2008.

State requirements - QLD

•  If intend to prescribe S8 drugs for longer than 8 weeks, forward a “Report to the Chief Executive” through the Drugs of Dependence Unit (DDU)

•  A treatment approval from the Chief Executive is required prior to treating, for any controlled drug for a patient considered to be drug dependent

•  For approvals and “Reports to the Chief Executive” contact the Drugs of Dependence Unit –  Phone 3328 9890 –  Fax 3328 9821

Preventing doctor-shopping

Medicare Australia Prescription Shopping Information Service

•  If patient suspected of getting medicine in excess of medical need, contact the Prescription Shopping Information Service: –  Complete and sign the registration form available at

www.medicareaustralia.gov.au •  Registration confirmed within 2 business days (fax) or by

mail –  Information Service available 24/7 for registered GPs to:

•  Find out if patient has been identified under the Prescription Shopping Program

•  Receive information on the amount and type of PBS medicine recently supplied to that patient

(  1800  631  181