Lecture 7: Adrenergic Agonists Flashcards
Receptor a1
-signals via Gq
-found on vascular, GI smooth muscle, and heart, and liver
-mediates vasoconstriction
a1 agonist clinical use
-nasal decongestion
-vascular failure in shock and supraventricular tachycardia
a1 ANTAgonist clinical use
-hypertension
-benign prostatic hyperplasia
-pheochromocytoma
direct a1 AGONIST drugs
-phenylephrine
-oxymetazoline
Phenylephrine (Neosynephrine)
-direct a1 agonist
-substrate for MAO
-high first pass metabolism
Phenylephrine clinical use
-a1 agonist
-nasal decongestant (bad tho)
-mydriasis w/o cycloplegia
-pressor
-vasoconstrictor in regional anesthesia
Phenylephrine administration
-parenteral
-oral
-local
2-aralkylimidazolines
-direct a1 receptor agonist
-basicity of imidazoline ring cause compunds to exist in ionized form at physiological pH
-partial agonists
2-aralkylimidazolines types
-naphazoline
-tetrahydrozoline
-oxymetazoline (visine)
2-aralkylimidazoline clinical use
-admin topically to promote vasoconstriction
-nasal and ophthalmic decongestants
Imidazoline
-basic ring structure
-cation is resonance stable = more basic
Beta receptor signaling
-Gs
-activate adenylyl cyclase
-increase cAMP
-cAMP dependent protein kinase
-phosphorylation of ion channels
B1 receptor location
-heart
-kidney
B1 receptor effect on heart
-increase force of contraction (inotropy)
-increase HR (chronotropy)
-increase conduction velocity in AV node
B1 receptor effect on kidney
-increase renin release
B1 AGONIST clinical use
-shock
-congestive heart failure
B1 ANTAgonist clinical use
-hypertension
-angina
-arrhythmias
-congestive heart failure
B2 receptor location
-smooth muscle
B2 receptor effect
-relax smooth muscle esp bronchial
-vasoDILATION
B2 AGONIST clinical use
-asthma
-premature labor
B2 ANTAgonist clinical use
Glaucoma
B3 receptor location
-bladder
B3 receptor effect
-relaxation
-prevention of urination
B3 AGONIST clinical use
-overactive bladder
Non-selective B agonists
-isoproterenol (isuprel)
B1-selective B AGONISTs
-Dobutamine (Dobutrex)
-Dopamine (intropin) (MOA complex)
B2 selective AGONISTS
-Terbutaline (brethine, bricanyl)
-metaproterenol (metaprel, alupent)
-albuterol (proventil, ventolin)
-salmeterol (serevent)
-ritodrine (yutopar)
B3-selective AGONISTS
-mirabegron (myrbetriq)
Isoproterenol (Isuprel)
-non-selective B AGONIST
-bronchodilation
-increase cardiac output
Isoproterenol (Isuprel) metabolism
-by phase II conjugation reactions
-by COMT
-not sensitive to MAO
Isoproterenol administration
-oral
-parenteral
-local (inhaled)
isoproterenol use
-asthma
-COPD
-cardiostimulant
Isoproterenol Action
-B1 and B2 AGONIST
-increase Cardiac Output
Isoproterenol effect on peripheral vessels
-stimulate B2
-vasoDILATION
-reduce peripheral resistance (may lower BP)
Isoproterenol clinical use
-emergency use to increase HR
-patients with bradycardia or heart block
-patients with SYSTOLIC dysfunction, SLOW HR, high systemic vascular resistance: after cardiac surgery in patients who previously used B-blockers
-astma and COPD