Week 23 - pain conditions Flashcards
What is pain?
The International Association for the Study
of Pain (IASP) definition for pain:
an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage
Acute pain
-Sudden onset - sharp or intense
-Serves as a warning sign of disease or threat to the body
-Caused by injury, surgery, illness, trauma, or painful medical procedures
-Lasts from a few minutes to less than 3 months
-Usually disappears whenever the underlying cause is treated or healed
Analgesics
An analgesic is a medication used to reduce pain
Anti-pyretic
Reduces body temperature
(fever)
Anti-inflammatory
Reduces inflammation
Paracetamol
Paracetamol inhibits the cyclooxygenase (COX) enzyme
->Child – suspension – easier to swallow and taste -> soluble tablets – easier to swallow and
absorbed more quickly
->Safe in pregnancy and breastfeeding
-Dose based on narrow age bands – not practical for consumers to calculate dose
based on body-weight (mg/kg)
Uses for paracetamol
For mild to moderate pain e.g.
-Headache
-Migraine
-Toothache (refer if abscess)
-Dysmenorrhoea
-Fever
-Osteoarthritis
->Less GI irritation compared with NSAIDs
Cautions for paracetamol
BNF – states appropriate sections for cautions and CI and interactions
-Risk factors for hepatotoxicity
->liver or kidney dysfunction
->Malnutrition, dehydration, alcohol misuse
->Older, frail patients
->Body weight<50kg, enzyme inducing medication
->Overdose – nausea and vomiting then liver failure (after 4-6 days)
Paracetamol suspension
For mild to moderate pain and as an antipyretic
Suitable for children:
->From 2 months(=>4kg)
for post-immunisation
pyrexia
->From 3 months for fever
and pain
Shake the bottle before use (for min 10 secs)
NSAID mechanism of action
Non-selective NSAIDs e.g. Ibuprofen, Aspirin, Naproxen, Diclofenac (topical)
->Inhibit prostaglandin (PG) synthesis by reversibly inhibiting cyclo-oxygenase
(COX) enzymes — COX-1 and COX-2
-COX-1 produces PG that help to maintain gastric mucosal integrity and platelet-initiated
blood clotting
-COX-2 produces PG that mediate pain and inflammation
NSAIDs - cautions
-Asthma (can induce asthma attack in 10%) - class effect
-Kidney impairment (decreases renal function)
-Cardiovascular disease and hypertension
-Inflammatory bowel disease such as crohn’s or ulcerative colitis
NSAIDs - contraindications
-Active peptic ulceration or GI bleeding
-Severe heart, renal or liver failure
-Pregnancy – non-selective NSAIDs contraindicated after 30 weeks of pregnancy (do not sell in pregnancy)
-Breastfeeding – aspirin contraindicated
NSAIDs - interactions
Interactions with other medications:
-Anticoagulant / antiplatelet
-Other NSAIDs
-Ciclosporin
-Diuretics
-ACE inhibitors
-Lithium
-Methotrexate
-SSRIs
Uses for NSAIDs
Mild to moderate pain:
-Sprians
-Strains
-Headaches
-Dysmenorrhoea
-Toothache
-Colds and flu
Ibuprofen
Adult oral dose = 200mg -
400mg up to 3 times a day (no more frequently than every 4 hours) -> max dose = 1200mg in 24 hours
-Take with or after food
->Nurofen caplets – not for
use in under 12 years
Naproxen
->Licensed for period pains and menstrual cramps for 15 -> 55 years
->Max three 250mg tablets per day
->Take with / just after meal or snack
->Not to be taken for more than three days in any one cycle
Ibuprofen 100mg/5ml suspension
Indications:
Fever, symptomatic relief of colds and influenza, mild to moderate pain – sore throat,
teething, toothache, headache, minor ache, toothache, headache, minor and sprains
Licensed doses:
3 to 6 months -> >5kg: 2.5ml three times a day for 24
hours only -> avoid in chickenpox
Codeine and dihydrocodeine
->Binds to Mu opioid receptors in the brain and spinal cord (CNS)
->Tolerance and dependence risk!!! – OTC supply limited to 3 days
Aspirin (acetylsalicylic acid)
-For mild to moderate pain in adults and children over 16
-Contraindicated in <16 years – can cause Reye’s syndrome (resulting in serious liver
and brain damage)
-Usual adult oral dose = 300mg – 600mg every 4 to 6 hours -> max dose = 3600mg / 24 hours
-Disclaimer = Aspirin 75mg for cardiovascular risk - not for pain - prolonged effect as an anti-
platelet
Codeine
->Pro-drug - Metabolised by
liver enzymes (CYP2D6) into morphine -> genetic variability in metabolism
->Acute moderate pain (not
anti-pyretic and not anti-
inflammatory)
->Combined with paracetamol, etc, OTC
Dihydrocodeine
->Acts directly on Mu opioid
receptors
->Acute moderate pain (not
anti-pyretic and not anti-
inflammatory)
->Combined with paracetamol, etc, OTC
Codeine/ Dihydrocodeine - side effects
Common side effects = constipation, nausea, drowsiness
->Although can be used in Pregnancy – do not sell OTC = refer to GP
->Contraindicated in breastfeeding
!!!Risk of addiction/ dependence -> max 3 days
Can make headaches worse, if used for > 3 days
Other active ingredients
Caffeine – a weak stimulant that is thought to enhance the analgesic effect and potentially increase absorption
Antihistamines - can act as muscle relaxants and can help with sleep
Dysmenorrhoea - primary
Age: 16-25
Onset of pain: Starts 6-12 months after menarche
A few hours before / during
menstruation
Pathophysiology: No underlying pelvic pathology
Excess PG, vasopressin, leukotrienes
Symptoms:
-Cramp / spasmodic pain in the lower abdomen and suprapubic area - may radiate to the back and inner thigh
-Can be associated with nausea,
vomiting, headache, fatigue, diarrhoea
-Usually self-limiting, lasts for first 1-3 days of menstruation
-Periods normal or light
-Responds to NSAID, paracetamol, COCP and sometimes heat and TENS
Dysmenorrhoea - secondary
Age: 30-45
Onset of pain: often starts after several years of painless periods, pain not consistently related to menstruation but is exacerbated by it
Pathophysiology: Underlying disorder e.g.,
-Endometriosis
-Uterine fibroids
-Pelvic inflammatory disease (PID)
-Intrauterine device (IUD) insertion
Symptoms:
-Lower abdominal pain associated with other features related to underlying pathology
-Periods often heavy
-Treatment based on
pathophysiology
Sprain
A torn, stretched or twisted
ligament
Symptoms: bruising, swelling, inability to move the joint e.g., sprained ankle or knee
Strain
The stretch or tearing of
muscles or tendons
Symptoms: tenderness and swelling
When to refer / danger symptoms
Treatment:
(R)est
(I)ce
(C)ompression
(E)levation
Refer:
-Fracture or dislocation – inability to weight bear
-Severe pain on movement
-Persistent pain, even when at rest
-Numbness - neuralgia symptoms
-Symptoms that have not improved after 48 hours
Osteoarthritis
-Affects knees, hips and small joints of the hand
-Loss of cartilage with joint remodelling
-Activity related pain
-Typically aged >45years
-No early morning
stiffness (or stiffness lasting no
longer than 30 minutes)
-Functional impairment-
movement limited
Osteoarthritis - pharmacological management
->Paracetamol or topical NSAID = first line
->Consider oral NSAID if simple analgesia ineffective (topical NSAID should then be discontinued)
->Consider weak opioid e.g. codeine when required if
NSAID not tolerated or not effective
Non-drug measures: weight management and exercise, physio
Back pain
-Most lower back pain is non-specific
-Most often seen in those aged 35 to 55 years
-Up to 60% of adults have lower back pain at some point in their lives
-Common cause of absence from work
Risk factors;
Non-modifiable: age, genetics
Modifiable: fitness, weight, mental health, job related activities, smoking
Back pain - red flags
Red flags from examination -> evidence of neurological deficit (in legs or perineum in the case of low back pain)
Red flags from patient history:
Possible fracture?
-Major trauma / minor trauma in elderly, or osteoporotic
Possible tumour / infection?
-Age <20 or >50 years old
-History of malignancy
-Constitutional symptoms
(fever, chills, weight loss)
-Recent bacterial infection
-Intravenous drug use
-Immunosuppression
-Pain worsening at night, or
when supine
Possible significant neurological
deficit?
-Severe or progressive sensory alteration, or weakness
-Bladder, or bowel dysfunction
Pharmacological management of lower back pain
1st line - oral NSAIDs e.g. Ibuprofen or naproxen
-Consider risk factors
-Use lowest effective dose for shortest duration
Codeine + Paracetamol ->only consider if NSAID contraindicated, not tolerated or
ineffective (for acute back pain only) -> paracetamol alone not recommended (evidence)
Management of LBP
Most effective treatment is to keep moving -> exercise
Sciatica
