medicinal chemistry- iii introduction wed. 2/ 5/ 1432h prof. dr. wafaa zaghary [email protected]...
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MEDICINAL CHEMISTRY-MEDICINAL CHEMISTRY-IIIIII
introductionWed. 2/ 5/ 1432H
Prof.Prof. Dr. Wafaa ZagharyDr. Wafaa Zaghary [email protected]
PHC 426
Different ‘types’ of pain, not just different degrees of pain
Multiple chemical mediators of pain
Optimal therapy matches the Optimal therapy matches the analgesic(s) with the type(s) of painanalgesic(s) with the type(s) of pain
Different ‘types’ of pain, not just different degrees of pain
Multiple chemical mediators of pain
Optimal therapy matches the Optimal therapy matches the analgesic(s) with the type(s) of painanalgesic(s) with the type(s) of pain
NSAIDs(non steroidal anti-inflammatory drugs)
Nonsteroidal Anti-Inflammatory Drug
A therapeutic agent which relieves pain and fever by inhibiting the inflammatory response.
These drugs are available over the counter and by prescription.
Some common examples include aspirin, ibuprofen, Celebrex, and less commonly acetaminophen (Tylenol).
Benefits of NSAIDs
Decrease pain and inflammation associated with rheumatic diseases.
Some studies show that Cox-2 inhibition may play a role in the modulation of intestinal polyps and colorectal cancer.
Other studies show that Cox-2 inhibition may prevent Alzheimer’s disease.
NSAID use
NSAIDs are available OTC
NSAIDs can be toxic on their own
People who take NSAIDs (elderly people) often take many drugs which can lead to dangerous interactions
NSAIDs are metabolized by multiple hepatic pathways
Common Side Effects
Common side effects to ALL NSAIDs are:Abdominal painDiarrheaNauseaFluid retention
These side effects occur in about 30% of all people taking NSAIDs.
Adverse effects
NephrotoxicBleeding problemsIncrease blood pressure
FDA requires medication guide be dispensed with every NSAID prescription – www.fda.gov/cder/drug/infopage/COX2/NSAIDmedguide.pdf
FDA fact: >70,000 hospitalizations per year and 10,000-20,000 deaths per year can be associated with NSAID use
Possible Side Effects
Cox-1 inhibitors GI ulceration, perforation,
toxicity Kidney failure Congestive heart failure
Cox-2 inhibitors GI problems May delay ulcer healing Increased risk of CV
disease Kidney failure* Increased risk factors include
being male, advanced age, and history of ulcers.
Startling Statistic
N Engl J Med 1999;340:1888-1899
20,197
16,685 16,500
10,503
5,338 4,441
0
5,000
10,000
15,000
20,000
25,000
Leukemia AIDS NSAIDsToxicity
MultipleMyeloma
Asthma CervicalCancer
# o
f D
eath
s p
er
Year
Categories of NSAIDsThere are two major categories for non-steroidal anti-inflammatory drugs
The first is non-selective anti-inflammatory drugs.
The second is selective anti-inflammatory drugs, COX-2 inhibitors.
The Inflammatory ResponseThe body’s response to a stimuli which causes pain and/or tissue damage.
Physiologically capillaries become “leaky” through vasodilation.
The response is initiated by the chemical messengers prostaglandins.
Biosynthesis of Prostaglandins
The goal is to inhibit the biosynthesis of prostaglandins in order to relieve the symptoms caused by the inflammatory response.
Prostaglandins are synthesized from arachidonic acid in a pathway mediated by the Cyclooxygenase enzymes.
FitzGerald, G. A. et al. N Engl J Med 2001;345:433-442
Production and Actions of Prostaglandins and Thromboxane
COX Expression Function Inhibitors
COX-1constitutively throughout the body
organ pain, platelet function, stomach
protection
NSAIDs
including aspirin
COX-2Inducible and constitutively in
brain, kidney
Inducible: inflammation, pain, feverConstitutive: synaptic
plasticity
NSAIDs, COX 2 inhibitors including celecoxib
(Celobrex )
COX-3Constitutively, high
in brain, heart
pain pathways, not inflammation pathways
acetaminophen some NSAIDs
Cox-1 vs. Cox-2 inhibitors
Selective COX-II Inhibitors
Anti-inflammatory with less adverse effects, especially GI events.Potential toxicities: kidney and platelets - ? increased risk of thrombotic events Role in Cancer preventionRole in Alzheimer’s disease
ASPIRIN Major Actions
Antipyretic action
Block the production of PGE2 to reset the hypothalamic temperature set point
ASPIRIN Major Actions
Antiplatelet/antithrombotic
Decreases platelet production of TXA2
by COX-1 to limit platelet aggregation and vasoconstrictiion
ASPIRIN/ NSAIDs ADVERSE GI EFFECTSBLEEDING
ULCERATION
OBSTRUCTION
Textbooks:
Williams, D.A. and Lemeke, T.L., Foye’s Principle of Medicinal Chemistry, Lippincott Williams & Wilkins, Philadelphia, PA., 5th Edition, 2002.
References
1. Tramer MR, et al. quantitative estimation of rare adverse events which follow a biological progression: a new model applied to chronic NSAID use. Pain. 2000 Mar;85(1-2):169-82.
2. DeBisschop M. What are the risks of long-term NSAIDs and COX-2 inhibitors? J of Family Practice. 2003 Mar;52(3):199-200.
3. Deviere J. Do selective cyclo-oxygenase inhibitors eliminate the adverse events associated with nonsteroidal anti-inflammatory drug therapy?
4. Oviedo JA, Wolfe MM. Clinical potential of cyclo-oxygenase-2 inhibitors. Biodrugs. 2001;15(9):563-72.
5. Hernandez-Diaz S, Rodriguez LA. Association between nonsteroidal anti-inflammatory drugs and upper gastrointestinal tract bleeding/perforation: an overview of epidemiologic studies published in the 1990’s. Arch Internal Medicine. 2000 Jul 24;160(14):2093-9.
References
6. Hawkey CJ. Non-steroidal anti-inflammatory drug gastropathy: causes and treatment. Scandinavian Journal of Gastroenterology 1996; vol. 220: 124-7.
7. Wolfe MM, Liechenstein DO, Sigh G. Gastrointestinal toxicity of nonsteroidal anti-inflammatory drugs. N Engl J Med1999;340:1888-1899
8. FDA and International Guidelines on Efficacy and Safety of
Cox-2 Inhibitors