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26 Cards in this Set
- Front
- Back
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What is the expected cardiovascular reponse to an alpha 1 adrenergic antagonist? When when they be used?
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If it is selective for alpha AR antagonist, one would see:
decrease in BP (PNS like effects) lowers peripheral vascular resistance it can also reverse epinephrine in the presense of alpha and beta AR stium because epi has affinity for alpha! Would be indicated for primary HTN |
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Alpha 1>>>> alpha 2
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prazosin
terazosin doxazosin tamulosin |
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What is the duration of action of alpha AR antagonists?
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most of the are reversible! dependent on half loife anf dissociation rate from receptor.
a few are irreversible! then duration relies on synthesis of new alpha AR. |
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alpha 1 = alpha 2
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phenotalimen
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alpha 1
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phenoxybenzamine
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alpha 2 >> alpha 1
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yohimbine
tolazoline rauwolscine |
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What is the action of alpha 1 AR antagonists?
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inhibits endogenous catecholamine-induced vasoconstriction in arteries and viens.
This decreases peripheral vascular resistance and lowers BP effect depends on sympathetic tone homeostatic response (barorecept) is activated and this would cause NE release. so if alpha 2 blockers are also present the response will be exaggerated since alpha 2 inibits NE release if used in combination with alpha 2 AR, |
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why is there more affect of alpha 1 AR antagonist when standing up?
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postural hypotension because veins are less affected
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What is the effect of alpha 2 adrenergic antagonists?
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if you block alpha 2 AR (which reduce SNS outflow and thus decrease BP), you will inhibit this inhibition of NE. this the BP will increase!
-may decrease glucose release from liver, increase insulin release, reduce smooth muscle tone in prostate and neck (decrease restostamce to urine outflow ), facilitate bladder evacuation, decrease platelet aggregation. |
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what happens if A2-AR antagonist presynaptically versus postmen?
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if at presynapse, NE release will be inhibited!
postsynaptically, NE release will increase and BP will increase. |
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Adverse effects of AR antagonists?
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postural hotn and syncope
take at bedtime and minimize dose first, increasing slowly HA, dizziness, asthenia impaired ejaculation |
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Phentolamine: Use, MOA, AE, Pharmacokinetics?
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tx: phenchromocytoma, erectile dysfunction
-nonselective (has some antagonist serotonint agonist activity) -competitive effects: decrease PVR, reflexive increase HR and release of NE via presynpatic alpha 2 AR limited oral absorption, peak within 1 hour? half life 5-7 SE: tachy, nasal congestion, HA |
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Phenoxybenzamine: Use, MOA, AE, Pharmacokinetics?
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– irreversible antagonist
– Some selectivity for α1-AR – Inhibits reuptake of NE – Not very selective also inhibits H1, Musc, 5-HT receptors -Tx pheochromocytoma) – Adverse effects postural hypotension, tachycardia, nasal congestion, inhibition of ejaculation CNS fatigue, sedation, nausea |
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Prazosin: Use, MOA, AE, Pharmacokinetics?
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(tx: hypertension, Raynaud’s syndrome)
– Selective for α1-AR – Relaxes arteries and veins – Very little tachycardia reflex – High first pass metabolism and t1/2 about 3 hr |
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Doxazosin
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Tx: hypertension and BPH)
– Alpha1-AR selective – Long T1/2 22 hr – Has active metabolite |
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Tamsulosin
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(Tx: BHP)
– T1/2 9-15 hr – Alpha1-AR selective - Some α1A- and α1D selectivity – Greater potency in inhibiting contraction of prostate smooth muscle compared to vascular smooth muscle |
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What are the effects of a beta-adrenergic
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Think beta blockers!
-slow hear rate -decrease oxygen requirement for heart -decrease latency perio, arterial HTN, does this by : decrease CO, inhibit renin secretion, may inhibit sympth tone via central effect. DOES NOT decrease normal arterial pressure! Decreases aqeous humore secretion thus lowers intraocular pressure |
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What are the differentiating properties of B AR antagonists?
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partial and ful antagon - some intrinsic sympth activity.
selectivity - if inhibit beta 1 only is cardioselective. membrane stabilizing - reductopm pf transmemb ion exchange (antiarrhth effect, caused by decrease in sodium entry and decreased depolarization) |
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Special characteristics of B AR antagonists?
levabatlol and carvedilol celiprolol propanolol carvedilol |
labetalol and carvedilol - also alpha 1 blocking.
celiprolol - beta 2 agonist effect propanolol - inhibits transport of iodine in thyroid follicle carvedilol - antioxidant properties nebivolol - no mimetic vasodiltator effect |
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what is the pharmacokinetic diff tween lipid soluble versus water soluble BAR antag blockers?
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lipo: well absorbed (can cross BBB), high first pass metabolism, highly plasma protein bound, large Vd, short t/12
water - less absorbed, less distrib in brain less liver metabol - eliminated unchanged smaller Vd less plasma protein binding |
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liposoluble BAR antag blockers?
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propanolol and oxyprenolol
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watersoluble BAR antag blockers?
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atenolol, nadolol, sotalol
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What are the cardiovascular uses of BAR antagonists
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angina pectoris
tachy due to thyroid related diseases arterial hypertension MI, unstable angina CHF |
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Other therapeutic uses of BAR ant?
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conditions with overstim of SNS such as migraine, termor, anxiety, alcohol addiction, glaucoma
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What are the AE of B adrenergic antagonist?
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aggrevation of CHF, bradyarr/cardia, aggreg of asthma,
hypoglycemia in DM over time rebound if sudden discount if overdose: tx with glucagon Dont use if BF. |
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Special actions of B AR antagonists?
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nitric oxide production
Beta AR agonist activity alpha1 antagonist block CA entry K channel opening antioxidant activity |
