Adrenergic Drugs Flashcards
Synthesis of endogenous catecholamines
Tyrosine->DOPA->Dopamine (DA)->Norepinephrine (NE)->Epinephrine (E)
MAO-A
Preferentially degrates 5HT, NE, DA
MAO-B
Preferentially degrades DA
Selegiline, isocarboxazid, phenelzine
MAOIs effective in treting depression
a1 receptor
Location and Effects:
Vascular smooth muscle – contraction
UG smooth muscle – contraction
Intestinal smooth muscle – relaxation
Heart – Incr inotropy (contractility) and excitabiltiy
Liver – glycogenolysis and gluconeogenesis
Gq subtype signaling
a2 receptor
Location and Effects: Pancreatic B cells -- decr insulin secretion Platelets -- aggregation Nerve -- Decr NE release Vascular smooth muscle -- contraction
Gi subtype signaling
B1 receptors
Location and effects:
Heart – Incr chronotropy (HR), inotropy (contractility), incr AV node conduction velocity
Renal juxtaglomerular cells – incr renin secretion
Gs signaling
B2 receptors
Location and Effects:
Smooth muscle – relaxation
Liver – glycogenolysis and gluconeogenesis
Skeletal muscle – glycogenolysis and K uptake
Gs signaling
B3 receptors
Adipose tissue – lipolysis
Gs signaling
D1 receptors
Gs signaling
Expressed in kidneys, mesentery, coronary arteries
Causes relaxation in vascular smooth muscle
D2,D3, D4
Gi signaling
D5
Gs signaling
Nigrostriatal pahtway
Projects from substantia nigra to corpus striatum
D1 and D2 receptors
Degeneration results in Parkinson’s
Mesolimbic Pathway
From ventral tegmental area to cerebral cortex and nucleus accumbens
Invoved w/ schizophrenia and addiction
Tubero-infundibular pathway
From hypothalamus (arcuate and para-ventricular nuclei) to the anterior pituitary
Inhibits release of prolactin
Area postrema
Associated w/ emesis (vomiting)
Noradrenergic system
From locus coeruleus to cerebral cortex, hypothalamus, cerebellum
Tx of ADHD
Pathway of action of cocaine and amphetamine
Nucleus tractus solitarius
REceives input from baroreceptors and chemoreceptors and regulates blood pressure
Epinephrine
Hormone w/ higher affinity for B-receptors
Incr HR and contractility, decr peripheral vascular resistance, incr blood flow to muscles, dilates airways
Norepinephrine
Higher affinity for a-receptors
Incr peripheral vascular resistance, decr capacitance of vessels, incr HR and contractility
Dopamine
Vasodilation in renal, mesenteric, coronary, and cerebral vasculature
Bind to all types of adrenergic receptors
Mediates Parkinson’s and schizophrenia
Isoproterenol
B-receptor selective
Vasodilation, incr HR and contractility
Ind. for bradycardia and heart block
Midodrine
Metabolite is selective a1-agonist
Tx of orthostatic hypotension by vasoconstriction to incr blood pressure
Phenylephrine
a1-selective agonist
Long half life
Nasal decongestion, mydriasis (dilated pupils), incr BP, antidote for chronic erection