Pharmocology Flashcards
What are the non-selective Cyclooxygenase inhibitors? (7)
- aspirin*
- sodium salicylate
- indomethacin
- ibuprofen*
- naproxen*
- phenylbutazon
- diclofenac
aspirin
- non-selective COX inhibitor (NSAID)
- irreversibly inhibits via covalent binding (acetylation)
- effect: decreases synthesis of thromboxanes and PGs
indomethacin
Non-selective COX inhibitor (NSAIDs)
ibuprofen
Non-selective COX inhibitor (NSAIDs)
naproxen
Non-selective COX inhibitor (NSAIDs)
- trade name: Aleve
- long half-life (>6 hrs)
Distinguish acetaminophen from the mechanism of NSAIDs.
reversibly inhibits cyclooxygenase (mostly in CNS - inactivated peripherally)
- antipyretic and analgesic, not anti-inflammatory
- drug of choice for fever/headache in infants
celecoxib
AKA celebrex
- the only COX-2 specific inhibitor that’s still on the market
- used particularly for rheumatoid arthritis, osteoarthritis, and ulcers
methotrexate
- folic acid analog (dihydrofolate reductase inhibitor)
- anti-rheumatic
- immunosuppressant
- inhibits T and B cell proliferation (arrests cell growth in G1 phase)
leflunomide
- anti-rheumatic
- immunosuppressant
- blocks pyrimidine synthesis by inhibiting dihydroorate dehydrogenase (reduces T and B cell proliferation)
- given as pro-drug (must be metabolized into active form)
etanercept
- anti-rheumatic
- TNF-alpha blocker
- often combined w methotrexate
infliximab
- anti-rheumatic
- TNF-alpha blocker
- often combined w methotrexate
anakinra
- anti-rheumatic
- inhibits IL-1 (IL-1 Ra analogue)
What are the two fates of the arachidonic acid pathway, and what are each of their committed enzymes?
- Leukotrienes; formation is catalyzed by 5-lipoxygenase
2. Thromboxane A2, prostacyclin, prostaglandins (committed step catalyzed by cyclooxygenase 1 and 2)`
Generally, what are the targets of corticosteroids vs NSAIDs?
- corticosteroids inhibit phospholipase A2 (which catalyzes the formation of arachidonic acid from membrane phospholipids)
- NSAIDs inhibit cyclooxygenase 1 and 2 (which catalyze the formation of thromboxane A2, prostacyclin, and prostaglandins from arachidonic acid)
Contrast the functions of cyclooxygenase 1 and 2.
COX-1: protective/ maintenance function throughout the body; generates low PG levels
- gastric mucosa
- platelet aggregation
- uterine contraction
COX-2: expression has to be induced by inflammatory mediators; expressed in kidneys and brain; generates high PG levels;
- local inflammation
- wound healing
- resistance to infection
Generally, what is the purpose of both cyclooxygenases?
They convert arachidonic acid to various prostanoids in different tissues
Which NSAIDs have a short half-life vs a long one?
Short (6 hrs): naproxen, salicylate, phenylbutazone
Which NSAIDs are COX-2 specific, and what is the main toxicity concern? (2)
Celecoxib (Celebrex, only one still on the market)* and Rofecoxib (Vioxx)
- increased risk of thrombosis
- other COX2 inhibitors pulled for cardiovascular effects
What is the only drug that irreversibly inhibits cyclooxygenases?
aspirin
What are the toxicity concerns associated with NSAIDs? (3)
- interstitial nephritis
- gastric ulcer (PGs protect gastric mucosa)
- renal ischemia (PGs vasodilate afferent arteriole)
What interaction is problematic with acetominophen and why?
Mixture with ethanol causes increased production of NAPQI (hepatotoxin metabolite) via CYP2E1
Which drug is most appropriate for treating fever/headache and why?
Acetominophen, particularly in young children. Aspirin can cause Reye’s syndrome
What are the long-term benefits of daily, low-dosage (80mg/day) intake of aspirin, and explain the mechanism.
- cardiovascular benefits: reduction of clotting and myocardial infarction
- reduced incidence of cancer (colorectal and others)
- mech: reduced platelet aggregation (bc of inhibited COX-1) and uninhibited vasodilation (doesn’t inhibit COX-2 as much as the COX-2 specific inhibitors or other nonspecific)
Why do COX-2 selective inhibitors cause cardiovascular problems? (Explain mech.)
- doesn’t inhibit COX-1 –> platelet aggregation (plaques)
- inhibits COX-2 –> no vasodilation