Pain and its management with medicines

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Pain and its management with medicines

• Jo Noble-Gresty
• Palliative Care Specialist Pharmacist
• St Charles Hospital
• Kensington and Chelsea Primary Care Trust
• May 2007

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Content

• What is pain?
• How we feel pain
• How we react to pain
• Types of pain
• Management of pain with medicines
• Questions

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What is pain?
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What is pain?

• Feeling or sensation
• Unpleasant
• Warning
• The word pain comes from the Latin poena
• meaning punishment or a penalty

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What is pain?

• An uncomfortable feeling that tells you that
  something is wrong with your body
• The bodys warning system, alerting you that
  something is wrong
• The International Association for the study of
  pain defines it as an unpleasant sensory and
  emotional experience associated with actual or
  potential tissue damage, or described in terms of
  such damage
• McCaffery and Pasero have defined it as
• whatever the experiencing person says it is,
  existing whenever he says it does

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How we feel pain

• Despite years of research,
• questions still remain as to
• exactly what happens
• between the moment you
• stub your toe and the
• moment you say ouch

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How we feel pain
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How we feel pain

• Thousands of receptor nerve cells in and beneath
  your skin sense heat, cold, light, touch,
  pressure and pain
• When you stub your toe these receptor nerve cells
  relay pain messages in the form of electrical
  impulses along a peripheral nerve to your spinal
  cord and brain

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How we feel pain

• In the spinal cord
• the nerve fibres that transmit pain messages
  such as the throbbing pain from that stubbed toe
  - enter the spinal cord in an area called the
  dorsal horn
• There they release neurotransmitters (chemicals)
  that activate other nerve cells in the spinal
  cord, which process the information and then
  transmit it up to the brain

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How we feel pain

• In the brain
• When news of your stubbed toe travels up the
  spinal cord, it arrives at the thalamus a
  sorting and switching station deep inside your
  brain
• The thalamus forwards the message simultaneously
  to 3 specialised regions of the brain
• the physical sensation region, the emotional
  feeling region
• and the thinking region
• The brain responds to pain by sending messages
  that moderate the pain the spinal cord

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How we react to pain

• Pain messages dont travel directly from pain
  receptors to your brain. In the spinal cord they
  meet up with specialised nerve cells that act as
  gatekeepers
• For severe pain linked to bodily harm the
  messages take an express route to the brain
• Weak pain messages may be filtered or blocked by
  the gate
• Nerve fibres that transmit touch also affect
  gatekeeper cells
• Rubbing a sore stubbed toe makes it feel better
  as the signals of touch decrease the transmission
  of pain signals

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How we react to pain

• Messages can change within your peripheral nerves
  and spinal cord
• Nerve cells in your spinal cord may release
  chemicals that intensify the pain, increasing the
  strength of the pain signal that reaches your
  brain
• Inflammation at the site of injury may add to the
  pain

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How we react to pain

• Messages from your brain also affect the gate
• Your brain sends messages that influence your
  perception of pain
• Your brain may signal nerve cells to release
  natural painkillers such as endorphins and
  enkephalins which diminish pain messages

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How we react to pain

• How you interpret pain messages and tolerate pain
  can be
• affected by your
• Emotional and psychological state
• Memories of past pain experiences
• Upbringing
• Attitude
• Expectations
• Beliefs and values
• Age
• Sex
• Social and cultural influences

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Types of pain

• Sharp or dull
• Intermittent or constant
• Throbbing or steady
• Stabbing or aching
• Minor to intolerable in intensity
• At a single site or over a larger area
• Referred from another area

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Types of pain

• Acute pain results from
• Disease
• Injury to tissues
• Inflammation
• Comes on suddenly
• Accompanied by anxiety or distress
• Cause can be diagnosed and treated
• Is self-limiting
• eg toothache, cut, burn, graze, bruise, sprain,
  post-surgery, fracture

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Types of pain

• Chronic pain
• Represents disease itself
• May occur after a previous injury
• Persists over a longer period of time than acute
  pain
• Can be resistant to medical treatments
• Can cause severe problems
• Eg arthritis, lower back pain, cancer pain,
  post-shingles
• pain, diabetic neuropathy, osteoporosis

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Types of pain

• Nerve pain due to
• Nerve compression
• Nerve damage
• Shooting, stabbing, burning,
• Alteration of sensation pins and needles,
  numbness, hypersensitivity to touch
• Eg sciatica, post-shingles pain, diabetic
• neuropathy, phantom limb pain

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Management of pain with medicines

• Analgesics (painkillers)
• Act in various ways on the peripheral and central
  nervous systems
• Modify the pain messages in the brain
• Enhance the release of the bodys natural
  painkillers (endorphins and enkephalins) which
  diminish pain messages

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Management of pain with medicines

• Using the WHO analgesic ladder

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Management of pain with medicines

• WHO analgesic ladder
• 3 step graded clinical approach
• Each step represents a level of pain by which
  analgesic selection is determined
• Pain control is individualised for each patient
• Treatment begins according to whichever level of
  pain the patient is experiencing

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Management of pain with medicines

• Oral preparations are first-line
• Analgesics should be taken regularly
• Breakthrough analgesia should be available
• The dose is increased according to the response
• If the pain remains uncontrolled or increases,
  the patient moves up to the next step
• Adjuvant agents can be used on any step

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Step 1 Mild pain Non-opioid

• Paracetamol
• Analgesic, reduces fever
• Dose 2 tablets up to FOUR times a day
• Not less than every 4 hours
• Do not take with any other Paracetamol-containing
  preparations
• OTC medicine
• Well tolerated (few side effects)
• Dangerous in overdose
• Drug interactions Warfarin

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Step 1 Mild pain Non-opioid

• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Eg Ibuprofen (OTC medicine)
• 200mg 600mg 3 to 4 times a day (max 2.4g daily)
• Diclofenac 50mg 3 times a day, SR 75mg twice a
  day
• Naproxen 250mg 500mg twice a day
• Piroxicam 10mg to 40mg once a day
• oral, gel, patch formulations
• Take oral with food

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Step 1 mild pain NSAIDs

• Analgesic, reduces fever, anti-inflammatory
• Caution in history of indigestion or stomach
  problems, asthmatics
• Side effects gastro-intestinal damage, kidney
  impairment, bleeding, fluid retention, breathing
  problems
• Drug interactions heart drugs, diuretics,
  warfarin

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Step 2 mild to moderate pain

• Opioids for mild to moderate pain /- non-opioid
• Eg Codeine, Dihydrocodeine, Tramadol
• In combination with Paracetamol
• Cocodamol 8/500 (OTC), 30/500 Maximum 8 tablets
  in 24 hours
• Codydramol 8/500 (OTC), 10/500 Maximum 8 tablets
  in 24 hours
• Not to be taken with any other Paracetamol
  preparation
• Side effects drowsiness, confusion, nausea,
  vomiting, constipation
• Drug interactions sedation and confusion with
  alcohol and other drugs that depress brain action
  (sleeping tablets, some antidepressants)

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Step 3 moderate to severe pain

• Opioids for moderate to severe pain /-
  non-opioid
• Eg Morphine (oral injection), Fentanyl
  (transdermal patch buccal lozenge), Oxycodone
  (oral injection), Diamorphine (injection)
• No ceiling dose
• Effective agents
• Not addictive when used to treat pain

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Adjuvant drugs

• Drugs not classified as analgesics but used to
  relieve specific
• types of pain
• NSAIDs inflammation, musculoskeletal pain
• Steroids inflammation
• Eg Dexamethasone up to 16mg daily, Prednisolone
  up to 60mg daily
• Side effects Moon face, fluid retention,
  diabetes, mood changes,
• gastric irritation
• (Osteoporosis, skin thinning, increased
  susceptibility to infection)
• Take with food
• Steroid card

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Adjuvant drugs

• Amitriptyline nerve pain
• 10mg to 100mg at night
• Side effects dry mouth, drowsiness, blurred
  vision,
• constipation, difficulty in passing urine
• Drug interactions other antidepressants
• Gabapentin nerve pain
• 100mg to 2400mg daily
• Side effects drowsiness, dizziness, confusion

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Adjuvant drugs

• Muscle relaxants muscle spasm
• Eg Diazepam 2mg to 5mg once daily, Baclofen 5mg 3
  times a day
• Side effects drowsiness, nausea (Baclofen)
• Bisphosphonates bone pain
• Eg Zoledronic acid or Pamidronate by intravenous
  infusion
• Ibandronate, Alendronate, Risedronate oral
  tablet
• Swallow whole with plenty of water while sitting
  or standing
• 30 minutes to 1 hour before breakfast, stand or
  sit upright for 30
• minutes to 1 hour after taking
• Side effects lowers calcium level in blood

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Pain management

• Most patients (90) with pain can be managed
  using the WHO analgesic ladder principles
• Combinations of classic analgesic with adjuvant
  medicines can provide good pain relief
• Monitoring of response and tolerability is
  essential