Receptors, Drugs, Mechanism of Action Flashcards
Alpha-1 adrenergic receptor
-Targets the Gq-alpha which activates Phospholipase C causing cascade from Phosphatidylinositol bisphosphate (PIP2) which activates IP3, DAG, and Ca2+ release
Alpha-2 adrenergic receptor
-Targets the Gi-alpha receptor which inhibits adenylate cyclase activity which prevents ATP from converting to cAMP (decreased cAMP activity)
Beta-adrenergic receptor
-Targets Gs-alpha receptor and activates adenylate cyclase which allows ATP to convert to cAMP (increased cAMP activity)
Agonist
A drug that binds to and activates a receptor in a way that brings about an effect
Antagonist
A drug that blocks or reduces the action of an agonist
Bioavailability (F)
Fraction of administered dose of a drug that reaches the systemic circulation
Role of Cytochrome P450 enzymes
Responsible for metabolism of 80% of all drugs in clinical use. (Heme proteins)
Consequences of enzyme induction
1) A drug can increase its own metabolism
2) A drug can increase the metabolism of co-administered drug
-May reduce drug plasma concentrations below therapeutic levels.
Drugs that inhibit cytochromes P450
1) Cimetidine
2) Erythromycin
3) Chloramphenicol
4) Grapefruit juice
Most common mechanism of drug excretion
Renal excretion
Protamine effects
Chemical Antagonist to heparin: Protamine is a protein that is positively charged, and counteracts the effects of heparin, an anticoagulant that is negatively charged
Tyrosine Kinase Receptors
Play an important role in cellular growth and differentiation
-Gain-of-function mutations in these receptors can lead to cancer
-Inhibitors of tyrosine kinase receptors are used as anticancer agents
Enzyme-linked receptors
Receptor tyrosine kinase family
-Class of receptors includes the insulin receptor
-Epidermal growth factor receptor (EGFR)
