Regal- Prostaglandins, Thromboxane and NSAIDS Flashcards
How are leukotrienes synthesized?
Phospholipase A2 cleaves membrane phospholipids into AA
5 LPO converts AA to 5HPETE then LTA4
What do LTC4 synthase or glutathione S transferase do to LTA4? What converts LTE4 to LTB4?
LTA4> LTC4 LTD4 LTE4-->LTA hydrolase LTB4
Where does LT synthesis occur?
Many cells and tissues
Predominately synthesized in leukocytes
What enzyme is associated w/ mast cells and basophils and what to they primarily make?
LTC4 synthase
peptido LTs
What enzyme is associated with endothelial cells and smooth muscle cells?
Glutathione S transferase
What are the 2 (4) types of leukotrienes?
LTB4
Peptidoleukotrienes
LTC4, LTD4, LTE4
How is LTB4 degraded?
Oxidized to inactive compound by enzymes in PMNs and others
What are the biological effects of LTB4?
Chemotactic for neutrophils
enhanced leukocyte adhesion
Decreased pain threshold–> hyperalgesia
What receptors does LTB4 target?
Non mentioned specifically but they’re distinct from peptide LTs
How is LTE4 degraded?
It is excreted in urine or acetylated and excreted in bile
LTC4, LTD4, LTE4 act on what receptor?
Cys LTR1
Cyst LTCR2
Interaction of peptido leukotriens w/ LTR1 leads to…
increased vascular permeability-> swelling
chemotactic for eosinophils and cytokine secretion
bronchoconstriction
increased mucous production
DC maturation and migration
smooth muscle proliferation
Interaction of peptido leukotrienes w/ LTR2 leads to…
endothelial cell and macrophage activation
fibrosis
What two peptido leukotrienes are important in asthma?
LTC4
LTD4
What drugs are leukotriene modifiers?
Zileuton
Zafirlukast
Montelukast
What is the therapeutic use of leukotriene modifiers?
bronchial asthma
CHRONIC not acute
What is the MOA of zileuton?
Inhibits 5-LPO
prevents synthesis of LTB4 and peptido LT
How is zileuton eliminated?
M: cyp450
What are the toxicities associated with zileuton?
drug interactions hepatic toxicity (req monitoring)
What is a unique property of zileuton related to asthma?
It can decrease the need for beta agonists in asthma
What is the MOA of zafirlukast and montelukast?
LTR antagonists (cys LTR1)
What is a toxicity associated w/ zafirlukast?
inhibits cyp450–> drug interactions
What is a unique property of montelukast?
it can be administered once daily w/out regard to meals
What are prostanoids?
PGD2 PGE2 PGF2 PGI2- prostacylcin TXA2
How are prostanoids synthesized?
Phospholipase A2 cleave membrane bound phospholipids into AA>
Cox acts on platelets to form products