Pain is defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage. (International Association For The Study Of Pains, 2015).
Introduction:
Pain is a symptom of an underlying condition
Because of its severity sometimes, pain has been used as an argument to permit people who are terminally ill to end their lives (Physician assisted suicide or euthanasia)
Pain that lasts a long time (> 6 months) is called chronic pain e.g cancer, peripheral neuropathy
Pain that resolves quickly ( <30 days) is called acute pain.
ASSESSMENT OF PAIN
Evaluation should include a detailed description of the pain ( sharp, burning, dull, aching etc)
Patient full history, psychosocial assessment, medication history paying attention to factors that influence the pain
Diagnostic laboratory test, imaging, including computer tomography (CT) and magnetic resonance imaging (MRI)
NB: pain is a subjective phenomenon and quantitative assessment is difficult (Breivik et al., 2008)
NEUROTRANSMITTERS AND PAIN
Various neurotransmitters in the dorsal horn of the spinal cord are involved in pain modulation
These include glutamate, GABA,NA, serotonin and peptide molecules e.g endogenous opiods – enkephalins, endorphins.
MAJOR TYPES OF PAIN
Nociceptive pain
Neuropathic pain
Psycogenic pain
Nociceptive pain
Caused by actual or potential damage to tissues e.g cut, burns, an injury
The pain is felt due to tiny nerve endings become activated or damaged (nociception)
Pain can be managed with traditional pain killers such as NSADS, opiod analgesics
Neuropathic pain.
is caused by a problem with one or more nerves themselves
the function of the nerves is affected in a way that it sends pain messages to the brain
Pain is often described as burning, stabbing, aching or like an electrical shock
Causes includes trigeminal neuralgia, diabetic neuropathy, multiple sclerosis, cancer, alcoholism.
Psychogenic pain
It can be induced by social rejection, broken heart, grief, or other emotional events
Headache, back pain, or stomach pain are some of the most common types of psychogenic pain
treatment may include psychotherapy, antidepressants , analgesics.
RESULTS OF UNTREATED PAIN
Depression, anxiety, decreased socialization
Sleep disturbance
Impaired ambulation
PAIN MGT GOALS
Relieve acute and chronic pain
Minimized side effects
Improve patient quality of life
DRUGS USED IN THE MGT OF PAIN
WHO Analgesic Ladder
Mild to moderate pain
Step 1: Non – opioids e.g Paracetamol or NSAIDS
Moderate to severe pain
Step2: Mild opioids e.g Codeine, with or without NSAIDS
Severe pain
Step 3: Strong opioids e.g Morphin
NON- STEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS)
Are effective for treating nociceptive pains
They have analgesic, antipyretic and anti-inflammatory actions
Are good for treating pains associated with rheumatoid arthtritis, gouty arthritis, headache, waist and back pains, toothache etc
Are not effective for treatment of visceral pain e.g angina pectoris
They don’t relieve neuropathic pain much
Examples; Aspirin, diclofenac, aceclofenac, ibuprofen,
Celecoxib etc
MOA
Inhibition of cyclooxynase enzymes (cox 1 and cox 2) thereby inhibit the synthesis of prostaglandin ( inflammatory mediator) and to some extent synthesis of the thromboxanes( platelet aggregation)
Adverse effects of NSAIDS
i. On GIT
Causes peptic ulcer or GIT bleeding
PGE 2 and PGI 2 inhibit gastric acid secretion, increase blood flow through the gastric mucosa and have cytoprotective action
ii. Nephrotoxicity
Cause chronic kidney failure
PGE2 and PGI 2 are powerful vasodilators synthesized in the renal medulla and glomeruli respectively and are involved in the control of renal blood flow and excretion of salt and water.
iii. Other adverse effects include;
Skin rashes ( Steven’s Jonson syndrome)
Prolonged bleeding (anti-platelet action)
NB: aspirin raises plasma urate levels at low doses by inhibiting uric acid secretion in the renal tubules. Thus should not be used in patients with gouty arthritis
DRUGS USED IN THE MGT OF NEUROPATHIC PAIN( Nep)
1st line analgesics
Tricyclic antideppresants (TCAs)
The TCAs provide the best evidence of efficacy in the mgt of Nep
MOA: these drugs block the re-uptake of NA and serotonin in the nerves and also have Na channel blocking
Example: Amitriptyline
Adverse effects: dry mouth, constipation, drowsiness
ii. Anticonvulsants
Example: Pregabalin or gabapentin
Gabapentin produce significant pain relief and significant improvement in measures of quality of life and mood
MOA: inhibit the release of excitatory neurotransmitters e.g glutamate and activate the GABA receptors (inhibitory NT)
Adverse effects: dizziness, headache, blurred vission, drowsiness
2nd Line analgesics
Example: Topical Lidocaine (5%)
Is used for patients with localized peripheral NeP such as postherpetic neuralgia
MOA: is a Na channel blocker
3rd Line analgesics
Example: Tramadol
4th Line analgesics
Opioid analgesics e.g Morphin
Antispastticity agents (muscle relants)
Example: Baclofen
Clinical uses- is an agent of choice for treating spinal spasticity and spasticity associated with multiple sclerosis
Adverse effects: depression, nausea, confusion
High strength vit B complex
Example: Neurovit forte
Used in treatment of peripheral neuropathy
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