Pain/Inflammation

Acute pain

Short lived pain caused by tissue injury; often served as a warning sign and resolves when the underlying problem heals

Examples of acute pain

Paper-cuts, burns, UTI, appendicitis

Chronic pain

Ongoing/recurrent pain lasting months or years; often continues even after the original injury heals

Examples of chronic pain

• Chronic low back pain

• Spinal stenosis

• Diabetic neuropathy

• Trigeminal neuralgia

Cutaneous pain

Pain originating from the skin or superficial structures

How is cutaneous pain often described

sharp, stabbing, burning, well-localized

Deep somatic pain

Pain originating from deeper structures- such as bones, muscles, ligaments, tendons, joints

How is deep somatic pain often described?

Dull, aching, throbbing, pressure-like

examples of deep somatic pain

• Bone fractures

• Muscle strains/sprains

• Joint degeneration

examples of cutaneous pain

• burns

• abrasions

• cuts

• post-herpetic neuralgia (shingles)

Visceral pain

Pain originating from internal organs- such as the heart, bladder, uterus, appendix

Examples of visceral pain

• Menstrual cramps

• Appendicitis

• Gallstones/gallbladder disease

How is visceral pain often described?

Deep, diffuse, hard to localize

Referred pain

Pain perceived in a different location from where it actually originates

Examples of referred pain

• Heart attack- left arm/jaw pain

• Gallbladder pain- right shoulder pain

• Laparoscopy- shoulder pain

Neuropathic pain

Pain cased by damage/dysfunction of the nervous system, rather than tissue damage; misfiring nerve fibers send faulty signals to the brain

How is neuropathic pain often described?

Burning, shooting, tingling, numbness, “electrical”, shocks

Examples of neuropathic pain

• Diabetic neuropathy

• Postherpetic neuralgia

• Trigeminal neuralgia

• Sciatica

• Carpal tunnel syndrome

What is a migraine

A recurrent, severe headache involving vascular and neurological changes in the brain

Who is more likely to experience migraines

Females- often begins in adolescence or early adulthood

Common migraine triggers/risk factors

• Hormones

• Dehydration

• Bright lights

• Strong odors

• Family history

• Stress

What medications are used to treat migraines

• NSAIDs

• Acetaminophen

• Triptans

Mechanism of action of triptans

Vasoconstricts blood vessels; blocks pain pathways and inflammation in the brain

Cluster headache

Severe, unilateral pain occurring in clusters/cycles- often at the same time each day

Who is more likely to experience cluster headaches

Males- also associated with smoking and alcohol use

How long do cluster headaches typically last

15 minutes - 3 hours

Why are cluster headaches called “suicide headaches”

The pain is extremely severe, and causes intense restlessness and agitation

Cluster headache treatments

• Abortive treatments (stops headaches): O2 and triptans

• Preventative treatments: CCBs and steroids

What is a tension headache

The most common type of headache, caused by muscle tension and stress- rather than vascular or neurological changes

How is a tension headache described

• Bilateral (both sides)

• Dull, aching pain

• Fells like a tight band around the head

• Commonly felt in forehead, temples, and back of neck

What triggers tension headache

Stress, anxiety, eye strain, poor posture

Are tension headaches more common in males or females

Females

how long do tension headaches last

30 minutes - 7 days

How are tension headaches treated

• NSAIDs (aleve/naproxen)

• Acetaminophen

• Combination medications (aspirin + caffeine)

How can tension headaches be prevented

• Exercise

• Relaxation

• Massage

• Maintaining good posture

What are COX-1 and COX-2?

Enzymes responsible for producing prostaglandins

What do prostaglandins contribute to

Pain, heat, redness, swelling, inflammation

Where is COX1 found

In almost all body tissues- including stomach, kidneys, platelets, intestines, etc.

Where is COX2 found

Primarily at sites of inflammation; also expressed in brain, bones, kidneys, and reproductive organs

Nonselective COX inhibitors

Medications that block COX1 and COX2 enzymes

What are the effects of nonselective COX inhibitors

• Decreases pain/inflammation

• Reduces fever

• Increases risk of GI irritation / bleeding / ulcers

Examples of nonselective COX inhibitors

• Aspirin

• Ibuprofen

• Diclofenac

• Naproxen

Selective COX2 inhibitors

Medications that block COX2 only- reducing inflammation with less GI irritation

Important risk of selective COX2 inhibitors

Increased cardiovascular risk

What is celecoxib (Celebrex)

Selective COX2 inhibitor used to decrease pain/inflammation

Celecoxib (Celebrex) contraindication

Sulfa allergy

NSAID mechanism of action

Blocks COX enzymes, preventing prostaglandin production, decreasing pain/inflammation/fever

How does acetaminophen work

Acts primarily in the brain and spinal cord to inhibit prostaglandin synthesis in the CNS

Does acetaminophen significantly inhibit COX enzymes?

No- it has little/no effect on peripheral COX enzymes

Primary uses if acetaminophen

Pain relief, fever reduction

Where is acetaminophen metabolized

Liver (monitor liver function due to risk of hepatotoxicity)

COX 1 enzymes increase the risk of...

GI irritation, stomach ulcers, and bleeding

acetaminophen increase the risk of...

Liver damage

Maximum daily dose of acetaminophen

4 grams

antidote for acetaminophen overdose

N-acetylcysteine (Mucomyst)

What are opioids used to treat

Moderate/severe pain

Do opioids eliminate the cause of pain?

No- they change how the brain/nervous system perceive and respond to pain

Endogenous opioids

Natural opioids substances produced by the body that act on receptors on nerve cells (neurons)

Opioid mechanism of action

Acts centrally in the brain/brainstem/spinal cord by binding to opioid receptors - especially mu receptors

What are the 3 main opioid receptors

• Mu

• Delta

• Kappa

What happens when Mu opioid receptors are activated

Produces powerful pain relief- but carries high risk of respiratory depression

Side effects of opioids

• Respiratory depression

• Over sedation

• Constipation

Examples of opioid agonists

• Morphine

• Codeine

• Fentanyl

• Methadone

• Oxycodone

Whats an opioid antagonist

Medication that blocks/reverses the effects of opioid drugs at opioid receptors, especially Mu receptors

What is naloxone (Narcan)

Opioid antagonist used as an antidote for opioid overdose

How can Naloxone (Narcan) be administered

• IV

• IM

• SQ

Possible side effects of Naloxone (Narcan)

• Aggression

• N/V

• Tachycardia

• Shivering/tremors

• Acute withdrawal

• Sweating

What are opioid agonist-antagonists

Medications that activate certain opioid receptors while blocking/partially activating others

What are the characteristics of opioid agonist-antagonists

• Moderate-strong analgesic activity

• Limited effective dose range

• Lower potential for abuse

Examples of opioid agonist-antagonists

• Butorphanol

• Pentazocine

What are adjuvant analgesics

Medications not primarily designed for pain relief- but enhance analgesia or treat specific types of pain

Why are adjuvant analgesics used with opioids?

To increase pain relief and help manage specific types of pain, such as neuropathic pain

Which antidepressants can be used as adjuvant analgesics?

• Tricyclic antidepressants (i.e amitriptyline)

• SNRIs (i.e duloxetine/cymbalta)

Which anticonvulsants can be used as adjuvant analgesics?

• Gabapentin (Neurontin)

• Pregabalin (Lyrica)

Which corticosteroids can be used as adjuvant analgesics?

• Prednisone

• Dexamethasone

Which CNS stimulant may be used as an adjuvant medication?

Methylphenidate