NSAIDs and Pain

Question 1

Prostaglandins

Answer 1

In the group of Eicosanoids
Cause inflammation and pain
Produced by oxygenation of arachidonic acid in cell membranes (either by COX 1 or COX 2)

Question 2

COX 1

Answer 2

Constitutively expressed
Found throughout the body
Constant levels
Involved in cell homeostasis (platelet function, cytoprotection of the GI tract, renal perfusion)

Question 3

COX 2

Answer 3

Inducible
Found in inflamed tissues
Present only transiently during inflammation and pain
Short half life
Promote inflammation and pain

Question 4

Physiological Effects of Prostaglandins

4 target tissues and effects

Answer 4

1. Smooth muscle (vascular = vasodilataion, GI = contraction)
2. Platelets (aggregation)
3. Kidney (increases renin release, and GFR)
4. NS (peripheral and central sensitization)

Question 5

Aspirin

Answer 5

Acetylsalicylic Acid
Derived from willow tree bark
Inhibits COX 1 and 2
Can take quite a bit per day

Question 6

How are other NSAIDs different from Aspirin?

Answer 6

They are also COX1/2 inhibitors
Similar pharmacology (analgesic, anti-inflammatory) but NOT anti-platelet aggregation
Long half life and more potent

Question 7

Negative side effects of NSAIDs

Answer 7

Prolonged use:
GI damage
Renal failure

Question 8

3 functions of PGI2 (and what is it)

Answer 8

It is a product of COX2 catalysis

1. Vasodilation
2. Platelet Inhibition
3. Protective of Cardiomyocytes

Question 9

Benefits of NSAID and Opioid combinations

Answer 9

Ease of prescribing combination
Less likelihood for opioid abuse
Highly effective analgesia while minimizing side-effects of individual compoents

Question 10

2 examples of NSAID and opioid combos

Answer 10

Vicodin: 500mg acetaminophen + 5mh hydrocodone
Vicoprofen: 200mg ibuprofen + 7.5mg hydrocodone

Question 11

Topical NSAIDs

Answer 11

Target pain in the periphery thereby minimizing centrally-mediated side effects
Analgesia easily applied to superficial joints

Question 12

4 topical NSAIDs approved by FDA

Answer 12

Pennsaid, Solarez, Voltaren, Flector

All contain diclofenac in differing concentrations

Question 13

Topical diclofenac

Answer 13

Systemic exposure is 17 times lower than oral
Average peak plasma [ ] is 158 times lower than oral
At least equal to oral in effectiveness
Takes about 4-12 weeks to start feeling effects
Higher safety margin

Question 14

Acetaminophen (paracetamol)

Answer 14

Good for rapid relief of acute and arthritis pain
Not COX1/2 inhibitor
Not anti-inflammatory
Less effective than other NSAIDs but still first line therapy for arthritis
Lacks side effects of ASA
Few drug drug interactions
Overdose causes kidney necrosis and hepatotoxicity

Question 15

Proposed mechanism of action of acetaminophen

Answer 15

1. Deacetylated in liver and produces P-aminophenol
2. Converted into an endocannabinoid in the brain
3. Endocannabinoid can reduce pain at CB1 receptor
4. Endocannabinoid reinforces descending serotoninergic pathways
5. Spinal release of 5-HT inhibits pain transmission