Term
| What are the 4 mechanisms of adrenergic receptor activation (with examples?) |
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Definition
1) Direct Receptor Binding: dopamine, epi, isoproterenol, and ephedrine
2) Promotion of NE release: amphetamines, ephedrine
3) Blockade of NE reuptake: cocaine and TCA
4) Inhibition of NE inactivation: MAOI |
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Term
| How do adrenergic agonists produce their effects? |
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Definition
-by activating adrenergic receptors
-sympathomimetic
-broad spectrum of applications |
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Term
| What's the difference between indirect and direct acting sympathomimetics? |
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Definition
-direct: most drugs in this chapter, peripherally-acting
-indirect: used for ability to activate adrenergic receptors in the CNS (although they still cause peripheral activation w/ toxicities like cardiac dysrhythmias from cocaine use) |
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Term
| What are the 2 chemical classifications of adrenergic agonists? What are the differences? |
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Definition
Catecholamines:
-Cannot be used orally (MAO and COMT are enzymes that destroy catecholamines administered by any route)
-BRIEF duration of action
-CANNOT cross BBB (polar molecules)
Noncatecholamines:
-CAN be given orally
-metabolized slowly by MAO (longer t1/2)
-more able to cross BBB |
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Term
Why do NE, dopamine, and dobutamine need to be administered by continuous infusions?
Why do they expire so soon?
Can they cross the BBB? |
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Definition
-bc they are catecholamines which have a rapid inactivation by MAO and COMT due to hepatic metabolism
-bc catecholamine molecules oxidize forming pigmentation (but dobutamine can be used up to 24h after it was made, even with discoloration)
-NO, bc they are polar. so they have minimal effects on CNS |
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Term
| The concept of receptor specificity is relative, not absolute. How does selectivity depend on the dosage of an androgenic agonist? |
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Definition
-at low doses, selectivity is MAXIMAL. as the dosage increases, selectivity declines.
-ex: when albuterol is administered in low to moderate doses the drug is highly selective for b2-adrenergic receptors, but if the dose is abnormally higher, it will activate b1 receptors as well |
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Term
Receptor specificity of Adrenergic Agonists:
-List the catecholamines and the receptors they activate |
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Definition
-Epinephrine: a1, a2, b1, b2
-Norepinephrine: a1, a2, b1
-Isoproterenol: b1, b2
-Dobutamine: b1
-Dopamine: a1, b1, dopamine |
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Term
Receptor specificity of Adrenergic Agonists:
-List the noncatecholamines and the receptors they activate |
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Definition
-Ephedrine: a1, a2, b1, b2
-Phenylephrine: a1
-Albuterol: b2 |
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Term
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Definition
2 responses for therapeutic use:
-VASOCONSTRICTION of blood vessels, skin, viscera, mucous membranes
-MYDRIASIS (pupil dilation) bc of radial muscle constriction |
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Term
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Definition
-located at presynaptic terminals (not on actual organs)
-causes inhibition of transmitter release
-no clinical therapeutic reasons to activate a2 in periphery
-BUT in CNS a2 causes: reduction of sympathetic outflow to the heart and blood vessels and relief of severe pain. |
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Term
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Definition
-Heart: inc. rate, force of contraction, inc. av conduction velocity
-Kidney: release of renin |
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Term
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Definition
-bronchial dilation
-uterine relaxation
-smooth muscle relaxation
-vasodilation of muscles and liver (and causes glycogenolysis) |
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Term
How does adrenergic receptor activation cause:
-Hemostasis?
-Nasal decongestion?
-Adjunct to local anesthesia?
-Increased blood pressure?
-Mydriasis? |
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Definition
-arrests bleeding via vasoconstriction
-mucosal vasoconstriction
-delays absorption of local anesthetic
-vasoconstriction
-radial muscle of iris |
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Term
| What are the adverse effects of a1 activation? |
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Definition
-hypertension
-Necrosis
-Bradycardia |
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Term
| What are the adverse effects of b1 activation? |
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Definition
-altered HR or rhythm (tachy or dysrhythm)
-angina pectoris (increased cardiac o2 demand bc of increased rate and contractility...this is why BB are essential in post MI pts) |
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Term
| What are 2 therapeutic applications of b2 activation? |
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Definition
| -to delay pre-term labor and asthma |
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Term
| What are adverse effects of b2 activation? |
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Definition
-hyperglycemia (result of breakdown of glycogen in liver and muscles)
-tremor (because activation of b2 in muscles enhances muscle contractions |
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Term
Receptor Activation: -Dopamine?
-Which receptors?
-Therapeutic uses?
Adverse affects?
Drug interactions? |
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Definition
-causes dilation of vasculature of kidneys, enhancing renal perfusion
-low therapeutic dose: dopamine
-moderate therapeutic dose: dopamine and beta1
-Very high therapeutic dose: a1, b1 and dopamine
-shock (inc. CO and renal perfusion)
-HF (inc. myocardial contractility)
-ARF (now proven ineffective)
-Tachycardia, necrosis w/ extravasation
-MAOIs, TCA, certain general anesthetics, diuretics |
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Term
Pathophysiology of anaphylactic shock?
tx? |
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Definition
-severe allergic response
-hypotension
-bronchoconstriction
-edema of glottis
-epi is TOC, sterios, benadryl is only helpful before histamine release, but not helpful when reaction is full blown |
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