Pharmacology of Pain
Medications
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

...
From: Bonica, “Thewww.indiandentalacademy.com 1990
Management of pain”
Nerve Fibers
Class

Velocity

Function

AA-

Fast
Fast

Motor

AA-

Intermediate
Intermediate

B
C

Small
Small

www.india...
Pain Fibers

•C
• A• Changes in Awww.indiandentalacademy.com
From: Dickinson & Fleetwood-Walker, Trends in Pharm. Sci. 20: 324, 1999.
www.indiandentalacademy.com
From: Yaksh, Trendswww.indiandentalacademy.com 1999.
in Pharm. Sci. 20: 329,
www.indiandentalacademy.com
Temporomandibular Joint
dysfunctions
• Disorders of muscles of
mastication(myofascial pain
dysfunction)
• Internal joint d...
Treatment of Myofascial
Pain Dysfunction
• Non-drug treatment
• Drug treatment
–NSAIDS, Opioids
–Tricyclic antidepressants...
Diagnosis

Drug Treatment

Acute and chronic pain

NSAIDS, Opioids,
acetaminophen

Myofascial pain
dysfunction

Analgesics...
Aspirin
• Analgesic
• Antiinflammatory
• Benefits in addition
to analgesia
• Inhibits COX

• Irreversible inhibitor of
COX...
Phospholipids
Phospholipase A2

Arachidonic Acid
COX

Prostaglandins

Lipoxygenase

Leukotrienes

Thromboxanes
Prostacycli...
Aspirin
Usual dose

Effect

80 – 160 mg

Antiplatelet

325 – 1000 mg

Analgesic, antipyretic

325 mg – 6 grams

Antiinflam...
Aspirin
(rapid)

Salicylate
(slower) *

Metabolites

In urine

www.indiandentalacademy.com
( * = http://www.hsc.wvu.edu/so...
Ibuprofen and other NSAIDS
• Analgesic
• Antiinflammatory
• Reversible
inhibitors of COX

• Nonselective
inhibitor of COX
...
Acetaminophen
• Analgesic
• Low effect on
peripheral COX
• Few drug-drug
interactions

• Not
antiinflammatory
• Analgesic ...
Acetaminophen
• May inhibit COX selectively in central
nervous system
• Only weak inhibitor of peripheral COX
(peroxide ef...
Acetaminophen – Mechanisms
of Action
• Central effect at level of spinal cord ( Little
effect on peripheral COX-1 or COX-2...
Acetaminophen
(conjugation)

Non-toxic
metabolites

(oxidation)

Toxic
metabolites*

www.indiandentalacademy.com
(* = http...
Selectively For COX-1 and -2
• Most NSAIDS (COX-1 > COX-2)
• Nabumetone (Relafen) and Etodolac
(Lodine) (COX-1 = COX-2)
• ...
Selective COX-2 inhibitors
• Analgesic
• Antiinflammatory
• Fewer adverse
effects

• Less experience
• More expensive

• B...
Celecoxib (Celebrex)
• Half life ~ 12 hours
• Metabolized in liver

• Has a sulfur atom – possible
problem in patients wit...
Rofecoxib (Vioxx)
• Half life ~ 17 hours
• Metabolized in the liver
• Does not contain a sulfur atom

www.indiandentalacad...
Opioids
• Much less ceiling
effect
• Work through
opioid receptor
mechanisms

• Adverse effects
• GI tract
• CNS
• Histami...
Sites of Opioid Action (*)
*

Midbrain

Medulla

*

Sensory
Nerve

Ascending
Tract

*
•
www.indiandentalacademy.com

Spina...
Some Opioid – Nonopioid
Combinations
•
•
•
•
•
•
•

Codeine + Aspirin (Empirin)
Codeine + Acetaminophen (Tylenol#?)
Dihydr...
Clinical Study (Diclofenac-100 mg
[D]; Acetaminophen-1000 mg [A];
codeine-60 mg [C])
50
45
40
35
30
25
20
15
10
5
0

***

...
NSAID +Acetaminophen
• Greater analgesic effect than either
alone
• Avoids adverse effects of opioids
• Similar half lives...
NSAID + Acetaminophen
• Ibuprofen
• 400-600 mg, q 4-6 hr
• max of 2400 mg q 24 hr

• Acetaminophen
• 600-1000 mg, q 4-6 hr...
NSAID + Acetaminophen
• Ibuprofen (400 mg q 4 hr) +
acetaminophen (600 mg q 4 hr)
• Ibuprofen (600 mg q 6 hr) +
Acetaminop...
Diagnosis

Drug Treatment

Acute inflammatory pain

NSAIDS, Opioids

Myofascial pain
dysfunction

Analgesics, tricyclics,
...
Thank you
For more details please visit
www.indiandentalacademy.com

www.indiandentalacademy.com
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Pharmacology of pain medications /certified fixed orthodontic courses by Indian dental academy

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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
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Pharmacology of pain medications /certified fixed orthodontic courses by Indian dental academy

  1. 1. Pharmacology of Pain Medications INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. From: Bonica, “Thewww.indiandentalacademy.com 1990 Management of pain”
  3. 3. Nerve Fibers Class Velocity Function AA- Fast Fast Motor AA- Intermediate Intermediate B C Small Small www.indiandentalacademy.com Touch, pressure Muscle tone Pain, temperature Motor Pain
  4. 4. Pain Fibers •C • A• Changes in Awww.indiandentalacademy.com
  5. 5. From: Dickinson & Fleetwood-Walker, Trends in Pharm. Sci. 20: 324, 1999. www.indiandentalacademy.com
  6. 6. From: Yaksh, Trendswww.indiandentalacademy.com 1999. in Pharm. Sci. 20: 329,
  7. 7. www.indiandentalacademy.com
  8. 8. Temporomandibular Joint dysfunctions • Disorders of muscles of mastication(myofascial pain dysfunction) • Internal joint derangement • Degenerative joint disease • Fractures, infections, tumors www.indiandentalacademy.com
  9. 9. Treatment of Myofascial Pain Dysfunction • Non-drug treatment • Drug treatment –NSAIDS, Opioids –Tricyclic antidepressants (amitriptyline) –Centrally-acting muscle relaxants –Glucocorticosteroids www.indiandentalacademy.com
  10. 10. Diagnosis Drug Treatment Acute and chronic pain NSAIDS, Opioids, acetaminophen Myofascial pain dysfunction Analgesics, tricyclics, centrally-acting muscle relaxants, glucocorticoids Neuropathic pain, neuralgias Carbamazepine, phenytoin, baclofen, tricyclics, gabapentin, others? www.indiandentalacademy.com
  11. 11. Aspirin • Analgesic • Antiinflammatory • Benefits in addition to analgesia • Inhibits COX • Irreversible inhibitor of COX • Nonselective inhibitor of COX (adverse effects) • Analgesic ceiling • Elimination kinetics • Drug-drug interactions • Reye’s syndrome www.indiandentalacademy.com
  12. 12. Phospholipids Phospholipase A2 Arachidonic Acid COX Prostaglandins Lipoxygenase Leukotrienes Thromboxanes Prostacyclin www.indiandentalacademy.com
  13. 13. Aspirin Usual dose Effect 80 – 160 mg Antiplatelet 325 – 1000 mg Analgesic, antipyretic 325 mg – 6 grams Antiinflammatory, tinnitus 6 – 10 grams Respiratory alkalosis 10 – 20 grams Fever, dehydration, acidosis > 20 grams Shock, coma www.indiandentalacademy.com
  14. 14. Aspirin (rapid) Salicylate (slower) * Metabolites In urine www.indiandentalacademy.com ( * = http://www.hsc.wvu.edu/som/pcol_tox/pharm361/lectures/djs/nsaid.htm
  15. 15. Ibuprofen and other NSAIDS • Analgesic • Antiinflammatory • Reversible inhibitors of COX • Nonselective inhibitor of COX (adverse effects) • Analgesic ceiling www.indiandentalacademy.com
  16. 16. Acetaminophen • Analgesic • Low effect on peripheral COX • Few drug-drug interactions • Not antiinflammatory • Analgesic ceiling • Liver toxicity www.indiandentalacademy.com
  17. 17. Acetaminophen • May inhibit COX selectively in central nervous system • Only weak inhibitor of peripheral COX (peroxide effects?) • Inhibits effects of substance P in CNS? • Inhibits effects of glutamate in CNS? www.indiandentalacademy.com
  18. 18. Acetaminophen – Mechanisms of Action • Central effect at level of spinal cord ( Little effect on peripheral COX-1 or COX-2) • Spinal antinociceptive effect is amplified by acetaminophen in the brain.* • The brain effect is mediated by an opioid mechanism expressed at the level of spinal cord.* * Raffa et al., J. Pharm. Exp. Therap. 295: 291, 2000. www.indiandentalacademy.com
  19. 19. Acetaminophen (conjugation) Non-toxic metabolites (oxidation) Toxic metabolites* www.indiandentalacademy.com (* = http://www.hsc.wvu.edu/som/pcol_tox/pharm361/lectures/djs/nsaid.htm
  20. 20. Selectively For COX-1 and -2 • Most NSAIDS (COX-1 > COX-2) • Nabumetone (Relafen) and Etodolac (Lodine) (COX-1 = COX-2) • Celecoxib (Celebrex) and Rofecoxib (Vioxx) ( COX-2 > COX-1) www.indiandentalacademy.com
  21. 21. Selective COX-2 inhibitors • Analgesic • Antiinflammatory • Fewer adverse effects • Less experience • More expensive • Blood • GI tract • Kidney www.indiandentalacademy.com
  22. 22. Celecoxib (Celebrex) • Half life ~ 12 hours • Metabolized in liver • Has a sulfur atom – possible problem in patients with allergies to sulfonamides www.indiandentalacademy.com
  23. 23. Rofecoxib (Vioxx) • Half life ~ 17 hours • Metabolized in the liver • Does not contain a sulfur atom www.indiandentalacademy.com
  24. 24. Opioids • Much less ceiling effect • Work through opioid receptor mechanisms • Adverse effects • GI tract • CNS • Histamine release • cranial pressure www.indiandentalacademy.com
  25. 25. Sites of Opioid Action (*) * Midbrain Medulla * Sensory Nerve Ascending Tract * • www.indiandentalacademy.com Spinal Cord
  26. 26. Some Opioid – Nonopioid Combinations • • • • • • • Codeine + Aspirin (Empirin) Codeine + Acetaminophen (Tylenol#?) Dihydrocodeinec+ Aspirin + caffeine (DHC Plus) Hydrocodone + Acetaminophen (Lortab ?/?) Oxycodone + Acetaminophen (Percocet) Pentazocine + Aspirin (Talwin compound) Propoxyphene + Acetaminophen (Wygesic) www.indiandentalacademy.com
  27. 27. Clinical Study (Diclofenac-100 mg [D]; Acetaminophen-1000 mg [A]; codeine-60 mg [C]) 50 45 40 35 30 25 20 15 10 5 0 *** *** ** * * Total Pain Relief D A A+C D+A D+A+C www.indiandentalacademy.com Breivik et al. Clin.Pharmacol. Ther. 66: 625, 1999
  28. 28. NSAID +Acetaminophen • Greater analgesic effect than either alone • Avoids adverse effects of opioids • Similar half lives for many NSAIDS and acetaminophen • Over-the-counter • Each has analgesic ceiling. www.indiandentalacademy.com
  29. 29. NSAID + Acetaminophen • Ibuprofen • 400-600 mg, q 4-6 hr • max of 2400 mg q 24 hr • Acetaminophen • 600-1000 mg, q 4-6 hr • max of 4000 mg q 24 hr www.indiandentalacademy.com
  30. 30. NSAID + Acetaminophen • Ibuprofen (400 mg q 4 hr) + acetaminophen (600 mg q 4 hr) • Ibuprofen (600 mg q 6 hr) + Acetaminophen (1000 mg q 6 hr) www.indiandentalacademy.com
  31. 31. Diagnosis Drug Treatment Acute inflammatory pain NSAIDS, Opioids Myofascial pain dysfunction Analgesics, tricyclics, centrally-acting muscle relaxants, glucocorticoids Carbamazepine, phenytoin, baclofen, tricyclics, gabapentin, others? Neuropathic pain, neuralgias www.indiandentalacademy.com
  32. 32. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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