Page 529 - First Aid for the USMLE Step 1 2020, Thirtieth edition [MedicalBooksVN.com]_Neat

phaRmaCology
`

Musculoskeletal, skin, and connective tissue ` phaRmaCology
Musculoskeletal, skin, and connective tissue ` dERmatology Don’t delete section iii 485

` mUsCUlosKElEtal, sKin, and ConnECtiVE tissUE—phaRmaCology

Arachidonic acid pathways

MEMBRANE
PHOSPHOLIPIDS
ANTI-INFLAMMATORY AGENTS
Phospholipase A 2 Glucocorticoids (corticosteroids)

LEUKOTRIENE
SYNTHESIS
(5-lipoxygenase) ENDOPEROXIDE SYNTHESIS
NF-κB IκB (cyclooxygenase)
Arachidonic acid
Zileuton COX-2 ONLY COX-1, COX-2
COX-2 Celecoxib Aspirin (irreversible)
LEUKOTRIENE 5-Lipoxygenase Other NSAIDs (reversible)
Ketorolac
RECEPTOR Diclofenac Ketorolac
Naproxen
ANTAGONISTS COX-1 Ibuprofen Naproxen
Indomethacin
Montelukast 5-HPETE Cyclic endoperoxides
Zafirlukast

Leukotrienes Prostacyclin Prostaglandins Thromboxane
LTC LTD LTE LTB PGI PGE PGE PGF TXA
4 4 4 4 2 1 2 2α 2
bronchial tone neutrophil platelet vascular uterine uterine platelet
chemotaxis aggregation tone tone tone aggregation
vascular tone vascular tone
Epoprostenol Alprostadil Dinoprostone Carboprost

LTB is a neutrophil chemotactic agent. Neutrophils arrive “B4” others.
4
PGI inhibits platelet aggregation and promotes Platelet-Gathering Inhibitor.
2
vasodilation.

Acetaminophen
mEChanism Reversibly inhibits cyclooxygenase, mostly in CNS. Inactivated peripherally.
CliniCal UsE Antipyretic, analgesic, but not anti-inflammatory. Used instead of aspirin to avoid Reye syndrome
in children with viral infection.
adVERsE EFFECts Overdose produces hepatic necrosis; acetaminophen metabolite (NAPQI) depletes glutathione and
forms toxic tissue byproducts in liver. N-acetylcysteine is antidote—regenerates glutathione.

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