Pharmacotherapy for pain involves the use of medications to alleviate or manage pain. The choice of pharmacological agents depends on the type, severity, and duration of pain, as well as individual patient factors such as age, comorbidities, and medication tolerances. Here is a comprehensive description of pharmacotherapy for pain, considering various classes of medications: 1. **Nonsteroidal Anti-Inflammatory Drugs (NSAIDs):** - NSAIDs, such as ibuprofen and naproxen, work by inhibiting the enzymes involved in inflammation and pain. - They are effective in managing mild to moderate pain, particularly that associated with inflammation, such as arthritis or musculoskeletal injuries. - However, long-term use may be associated with gastrointestinal side effects, so caution is advised. 2. **Acetaminophen:** - Acetaminophen is a pain reliever and fever reducer that is generally considered safer for the stomach than NSAIDs. - It is commonly used for mild to moderate pain and is often recommended for individuals who cannot tolerate NSAIDs. - Excessive use, however, can lead to liver damage, so dosing recommendations should be followed carefully. 3. **Opioids:** - Opioids, such as morphine, oxycodone, and hydrocodone, are potent analgesics that can be effective for moderate to severe pain. - They work by binding to opioid receptors in the brain and spinal cord, altering the perception of pain. - Due to the risk of tolerance, dependence, and addiction, opioids are typically reserved for short-term use or for chronic pain that has not responded to other treatments. 4. **Adjuvant Medications:** - Certain medications originally developed for other purposes, such as anticonvulsants (e.g., gabapentin, pregabalin) and antidepressants (e.g., amitriptyline, duloxetine), can be used as adjuvants in pain management. - These medications can help manage neuropathic pain and may enhance the effects of other analgesics. 5. **Corticosteroids:** - Corticosteroids, such as prednisone, may be used for short-term relief of pain and inflammation, particularly in conditions like rheumatoid arthritis or certain inflammatory disorders. - Prolonged use is generally avoided due to the risk of side effects. 6. **Topical Analgesics:** - Topical formulations, including creams, patches, and gels, containing analgesic agents like NSAIDs, lidocaine, or capsaicin, can be applied directly to the affected area for localized pain relief. 7. **Muscle Relaxants:** - Muscle relaxants, such as cyclobenzaprine or baclofen, may be prescribed to alleviate pain associated with muscle spasms or tension. It's important for healthcare professionals to conduct a thorough assessment of the patient's pain and medical history to tailor the pharmacotherapy approach. The goal is to achieve adequate pain control while minimizing the risk of side effects and considering the overall well-being of the patient. Regular monitoring and communication.

1. PAIN
Pharmacotherapy
Presented By: Mr. Bigin Gyawali
https://www.youtube.com/@BiGs8
bigingyawali@gmail.com
Universal College of Medical Sciences and Teaching Hospital

2. • Definition & Introduction
• Brief Epidemiology
• Pathophysiology/Pain Pathways
• Clinical Presentation of Pain
• Diagnostic Investigations
• WHO Analgesic Ladder
• Main Medicines and Their Brief Profile
Contents
BIGIN
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3. PAIN
BIGIN
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The word PAIN is derived from Latin word “Peone” and the Greek word
“Poine” meaning “Penalty or Punishment”.
According to “International Association for the Study of Pain”, the pain is
defined as an unpleasant sensory and emotional experience associated with
actual or potential tissue damage or in terms of such damage.

4. PAIN
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"Pain" is a broad Symptom rather than a Specific Disease.
The intent of the “Pain the Fifth Vital sign” campaign
(Presidential Address to the American Pain Society, 1996,
Campbell) was to encourage doctors and nurses to listen to
their patients and assess their pain.
This was because health care professionals often ignored
patients' suffering from pain.

5. Classification Of PAIN
BIGIN
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Pain
Acute Pain Chronic Pain
Somatic Pain
Visceral Pain
Nociceptive Pain
Neuropathic Pain

6. Acute PAIN
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Acute pain is defined as the pain of a shorter duration that
subsides as the healing process occurs.
This pain may range from mild to severity in intensity.
Causes of acute pain include:
• Post operative pain
• Procedural pain
• Traumatic pain

7. Trauma
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8. Somatic PAIN
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It result of activation of nociceptors (sensory receptors) sensitive
to noxious stimuli in cutaneous or deep tissues. It is experienced
locally and described as constant, aching and gnawing.
Somatic pain is the most common type of pain in patients with
cancer and bone metastases are the most prevalent cause.

9. Visceral PAIN
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It is mediated by nociceptors. It is described as deep, aching and
colicky. It is poorly localized and often referred to cutaneous
sites, which may be tender.
In cancer patients, results from stretching of viscera by tumour
growth.

10. It usually lasts longer than 3-6 months and ranges in intensity
from mild to severe. Chronic pain associated with malignancy
includes
• The pain of cancer
• Acquired immuno deficiency syndrome (AIDS)
• Multiple sclerosis
• Sickle cell anaemia
• End stage organ system failure
Chronic PAIN
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11. Nociceptive PAIN
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Neuropathic PAIN
It may be visceral or somatic. It is usually derived from the stimulation
of pain receptors. It may arise from tissue inflammation, mechanical
deformation, ongoing injury or destruction. It responds well to
common analgesic medications and non drug strategies.
It involves the central and peripheral nervous system. It does not respond
as predictably as nociceptive pain to conventional analgesics. It may
respond to adjuvant analgesic drugs.

12. EPIDEMIOLOGY
Pain is the most common symptoms that provokes people to seek
medical attention. Despite this, the epidemiology of pain is not as well
documented as it is the incidence of many chronic diseases.
50 million Americans are partially or totally disabled because of pain.
The annual cost of pain to American society can be estimated to be in
the million dollars.
In the Michigan pain study, 70% of chronic pain patients claimed to
have pain despite treatment, with 22% believing that treatment
worsened pain.

13. The point prevalence of chronic pain was 53.3% (n = 277). The point
prevalence of chronic pain of predominantly neuropathic origin was
12.7% (n = 66). Chronic pain was associated with female gender, older
age, and manual labour occupations
Prevalence of low back pain ranged from 52% to 91%, and
musculoskeletal pain ranged from 35% to 70%.
The prevalence of self-reported joint pain in Nepal was 17% with higher
prevalence for older adults, females, ever married, none/less than
primary education, smoker, lowest wealth quintile, homemaker, those
with sufficient physical activity and those living in the Karnali province
of Nepal.

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PATHOPHYSIOLOGY
The Pathophysiology of pain is mainly classified into two pathways
• Nociceptive pathway
• Neuropathic pathway
1) Nociceptive Pathway
Nociceptive pain typically is classified either:
• Somatic: Arising from skin, bone, joint, muscle or connective
tissue
• Visceral: Arising from internal organs such as large
intestine/pancreas

15. BIGIN
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• Stimulation
• Transmission
• Perception
• Modulation
The mechanisms involved in nociceptive pathway are:

16. The First step leading to sensation of pain is the stimulation of
free nerve endings known as nociceptors. These receptors are
found in both somatic and visceral structures and are activated
& sensitized by mechanical, thermal & chemical impulses.
Noxious stimulus sensitizes and/or stimulates nociceptors and
causes the release of neurochemicals like bradykinins, K+,
prostaglandins, histamine, leukotrienes, serotonin and
substance P that also sensitize and/or stimulate nociceptors.
This activation leads to the production of action potential (AP).
BIGIN
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• Stimulation

17. The action potential continues from the site of noxious
stimulus to the dorsal horn of spinal cord and then ascends to
higher centres in the CNS.
Transmission takes place in at least 5 pathways:
• Spinothalamic tract
• Spinoreticular tract
• Spinomesencephalic tract
• Dorsal column post synaptic spinomedullary pathway
• Propriospinal multisynaptic ascending systems
BIGIN
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2. Transmission

18. Conscious experience of Pain.
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3. Perception
4. Modulation
Inhibition of nociceptive impulses. Neurons from the brain
stem descend to the spinal cord and release substances such
as endogenous opioids, serotonin and norepinephrine that
inhibit transmission of nociceptive impulses.

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2. Neuropathic Pathway
Neuropathic pain is distinctly differ from nociceptive pain. It is the pain
sustained by abnormal processing of sensory input by the central or
peripheral nervous system.
e.g. low back pain, diabetic neuropathy, post herpetic neuralgia, cancer
related pain, spinal cord injury, multiple sclerosis etc.
The mechanism responsible may be the nervous system’s endogenous
dynamic nature. Nerve damage or persistent nerve stimulation may
cause pain circuits to rewire themselves both anatomically and
biochemically.

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23. BIGIN
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This Produces:
• Spontaneous nerve stimulation
• Autonomic neuronal pain stimulation
• Progressive increase in the discharge of dorsal horn neurons

24. Clinical Presentation of PAIN
GENERAL: Patients may be in obvious acute distress (trauma pain)
or appear to have no noticeable suffering (chronic/persistent)
SYMPTOMS:
• Pain can be described as sharp, dull, burning, shock like,
tingling, shooting, radiating, fluctuating in intensity and varying
in location.
• Overtime, the same pain stimulus may cause symptoms that
completely change (e.g. sharp to dull, obvious to vagus).
• Non specific symptoms include anxiety, depression, fatigue,
insomnia, anger and fear.

25. SIGNS:
• Acute pain can cause hypertension, tachycardia,
diaphoresis, mydriasis and pallor, but these signs are not
diagnostic.
• In some acute cases and in most chronic/persistent pain,
there may be no obvious signs.
LABORATORY TESTS:
• Pain is always subjective
• There are no laboratory tests that can diagnose pain
• Thus pain is best diagnosed based on patient description
and history.

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Pain Management
Goals of
Treatment
• To decrease intensity and duration of pain
• To decrease suffering and disability associated with pain
• Minimize ADRs or intolerance to pain management therapy
• Monitor and evaluate for therapeutic and unwanted
effects
• Improve patient’s quality of life

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Non-Pharmacological Treatment
Radiotherapy: For the management of bone
metastasis.
Physiotherapy: Spinal manipulation, massage,
application of heat or cold.
Stimulation therapy: Transcutaneous electrical nerve
stimulation (TENS).
Physiological intervention: Cognitive, behavioural and
social therapy.

28. Drugs & Dose
Aspirin: 150-600mg orally BD
Acetaminophen: 325-650mg orally
Meclofenamate: 50-100mg orally
Mefenamic acid: 250-500mg orally
Etodolac: 400mg or 200-400mg orally
Diclofenac: 50-100mg IM or orally
BIGIN
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Pharmacological Treatment
Non-Opioid Analgesics

29. Drugs & Dose
Morphine: 10-50mg orally or 10-15mg IM or
SC
Codeine: 30-60mg orally
Methadone: 2.5-10mg oral/IM
Tramadol: 50-100mg oral/IM
BIGIN
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Opioid Analgesics

30. BIGIN
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Adjuvant Drugs
• Tricyclic antidepressants: Amitriptyline
• Anti convulsants: Carbamazepine, sodium
valproate
• Corticosteroids: Prednisolone, dexamethasone
• Anxiolytics: Diazepam, lorazepam
• Muscle relaxants: Baclofen

31. BIGIN
GYAWALI
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WHO Analgesic
Ladder
The three main principles of
the WHO analgesic ladder
are:
By the clock
By the mouth
By the ladder.

32. Thank You
BIGIN GYAWALI
PRESENTED BY
BIGIN
GYAWALI
PRESENTED
BY
Universal College of Medical Sciences and Teaching Hospital
PAIN Pharmacotherapy
Email: bigingyawali@gmail.com