1 & 2 - Pain & Pain Management Flashcards
Can pain be perceived differently across ethnic origins and gender?
Yes
What is the relationship between pain sensitivity and COMT activity? What does this mean?
- Low pain sensitivity has higher levels of COMT activity
- Therefore, COMT activity has inverse relationship to pain sensitivity
- This means there is a genetic difference in how people perceive pain
How can pain be classified?
- Based on duration
1) Acute - mild to severe; most intense at time of injury; generally decreases upon healing or removal of source
2) Chronic - lasting more than 6 months; persists when initial cause removed or medically resolved; may not have underlying cause; very difficult to treat
Which types of pain are generally acute?
- Nociceptive (somatic or visceral)
- Post-op or post-traumatic pain
- Burn
- Childbirth
- Acute headache
What can chronic pain be classified into?
1) Malignant - cancer, HIV/AIDS, MS, organ failure
2) Non-malignant - lower back pain, chronic degenerative arthritis, OA, RA, migraine
What are the 3 main types of pain, classified by source?
1) Physiological
2) Neuropathic
3) Inflammatory
What is physiological pain?
- Cutaneous, somatic, and visceral
- Cutaneous = skin and surface tissue
- Somatic = ligaments, tendons, bones, blood vessels; often described as dull or aching; generally able to point directly to pain location
- Visceral = body organs, internal cavities; described as throbbing or gnawing/aching pain; difficult to locate; may be distant from source
What is nociceptive pain?
- Directly caused by the stimulation of pain nerve endings to tissue injury or disease infiltration
- Pain resulting as a consequence of peripheral nerve damage
- Can result from limb amputation, spinal surgery, viral infections (shingles), or worsening disease states (diabetes, AIDS, MS)
What are the first line treatments for neuropathic pain (based on table 4 of reference)?
- Tricyclic antidepressants
- Calcium channel alpha2-beta ligands (gabapentin and pregabalin)
- SSNRIs (duloxetine and venlafaxine), only based on NeuPSIG guidelines
What is inflammatory pain?
- Originates from infection or inflammation as a result of initial tissue or organ damage (NSAIDs)
- Can be further defined as pain arising from tissue damage and infiltration of immune cells
What category of pain does cancer fall under?
Sometimes classified separately, b/c can have both nociceptive and neuropathic components, palliative and breakthrough pain
Describe the WHO guideline for pain management
1) Pain persisting or increasing – non opioid +/- adjuvant
2) Pain persisting or increasing – opioid for mild to moderate pain +/- non opioid and +/- adjuvant
3) Freedom from cancer pain – opioid for moderate to severe pain +/- non opioid and +/- adjuvant
What are the classes of drugs used in pain management?
- Acetaminophen
- NSAIDs and coxibs (selective COX inhibitors)
- Opioids
- Opioid substitution therapy (methadone, buprenorphine)
- Tramadol and tapentadol (open-chain opioids)
- Antidepressants
- Anti-epileptics
- 5-HT1 agonists (triptans, headache, migraines)
- Local anesthetics (topical = lidocaine)
- Capsaicin
What is one of the oldest recorded medications?
Juice or latex from unripe seed pods of the poppy Papaver Somniferum
When was morphine first introduced?
- Early 1800’s
- The first total synthesis of the alkaloid morphine was performed in 1952
What is diacetylmorphine? When was it first marketed and as what?
- Heroin
- Marketed in 1898 as the first non-addictive analgesic, anti-diarrheal, and anti-tussive agent
What is an opioid?
All agonists and antagonists, either natural or synthetic
What is an opiate?
Drugs derived from opium, poppy plants
What is an opioid receptor?
Group of G-protein-coupled receptors w/ opioid ligands
What is a narcotic?
All drugs of abuse, not just opioids
What are side effects of opioid analgesics?
- Addictive “narcotic effects”
- Euphoria
- Excessive sedation
- Respiratory depression
- Withdrawal sx
What are the 3 families of endogenous opioid peptides?
- Enkephalin
- Endorphin
- Dynorphin
What is the principle effect of opioids?
Inhibition of adenylate cyclase which decreases cAMP production and simultaneously lowers overall perception of pain
Do opioids bind directly to adenylate cyclase?
No, bind to a GPCR which downregulates adenylate cyclase
What is the hypothesis for the cause of tolerance?
Receptors uncouple from G-protein, causing a need for higher doses b/c opioid can’t have an effect on adenylate cyclase
What is the hypothesis for the cause of addiction?
Chronic decrease in cAMP triggers compensatory increase in adenylate cyclase synthesis (enzyme induction) => increased cAMP concentration in brain