Adrenergic Antagonists, Drug Experiments B&B Flashcards
Phenoxybenzamine versus phentolamine
both are nonselective alpha blockers (alpha1/2)
Phenoxybenzamine = irreversible, used in pheochromocytoma
Phentolamine = reversible
Both can cause hypotension, and subsequent reflex tachycardia
what side effect should you be wary of with alpha blockers such as phenoxybenzamine and phentolamine?
can cause hypotension and subsequent reflex tachycardia
Phenoxybenzamine = irreversible, used in pheochromocytoma
Phentolamine = reversible
nonselective alpha blocker used to treat pheochromocytoma
Phenoxybenzamine - binds irreversibly, which is helpful in the use of pheochromocytoma in which there are very high catecholamines (thus high HTN)
What is the effect of phentolamine?
nonselective alpha blocker (alpha1/2)
Historically used to reverse “cheese effect” - when MAOi drugs were used to treat depression, they would block NT breakdown, as well as breakdown of tyramine (found in cheese)
tyramine has similar structure to dopamine, and in high quantities can cause dangerously high HTN
what kind of drugs are prazosin, terazosin, doxazosin, and tamsulosin? What are they used to treat (2)?
selective alpha1 blockers used in HTN and urinary retention in BPH
Name 4 selective alpha1 blockers used to treat hypertension and urinary retention in BPH
- prazosin
- terazosin
- doxazosin
- tamsulosin
What kind of drug is mirtazapine and what is it used to treat?
selective alpha-2 blocker used to treat depression - affects serotonin and NE levels in CNS
selective alpha-2 blocker used to treat depression
Mirtazapine
what type of beta blockers are esmolol, atenolol, and metoprolol?
selective beta1 blockers
MET with ESsential ATtention
(focusing SELECTIVELY on beta1)
what type of beta blockers are propranolol, timolol, and nadolol?
nonselective (beta1/2) blockers
NADa (“not”) PROPer nor TIMid
(will take anything and not afraid to speak out - will block beta 1 or 2)
what type of beta blockers are carvedilol and labetalol?
beta1 + beta2 + alpha1 blockers
CARVEing out time for OTHERS (alpha1) and not LABEling (beta1 or beta 2 - doesn’t matter!)
what kind of beta blockers are pindolol and acebutolol?
partial beta agonists
Partial (Pindolol) Agonists (Acebutolol)
what are the heart rate effects of activating the following receptor types?
a. beta1
b. beta2
c. alpha1
d. alpha2
a. beta1 —> tachycardia
b. beta2 —> vasodilation —> reflex tachycardia
c. alpha1 —> vasoconstriction —> reflex bradycardia
d. alpha2 —> decrease NE —> bradycardia
what is the primary determinant of systolic vs diastolic BP?
systolic BP - cardiac output
diastolic BP - peripheral resistance
a drug is given which causes HR, MAP, and SBP to increase - which adrenergic receptor was activated?
beta1: increases HR, contractility, and CO —> main effect is to raise systolic BP
a drug is given which increases HR but decreases MAP and DBP - which adrenergic receptor was activated?
beta2: vasodilator, causing diastolic BP to fall —> overall result is fall in mean blood pressure and reflex tachycardia
a drug is given which decreases HR but increases MAP and DBP - what type of adrenergic receptor was activated?
alpha1: vasoconstrictor, main effect is to increase diastolic BP —> overall, rise in mean blood pressure and reflex bradycardia
a drug is given which decreases HR and MAP - which adrenergic receptor was activated?
alpha2: blunts sympathetic activity, causing HR and MAP to fall
what is the mechanism of clonidine and methyldopa used to treat hypertension?
alpha2 agonists: blunts sympathetic activity, causing HR and MAP to fall
describe the effects of dobutamine on heart function (CO, HR, MAP)
mostly beta1 agonist —> raise CO and HR
some beta2 AND alpha1 action —> lower MAP, but only slightly
affects myocytes (inotropy) > SA node (chronotropy)
describe the effects of dopamine and epinephrine on heart function (CO, HR, MAP)
beta1,beta2,alpha1 agonists
increase CO (—> increase SBP), HR, and MAP
can also increase DBP (via alpha1) but dose dependent
describe the effects of norepinephrine on heart function (CO, HR, MAP)
alpha1»_space;> beta1 agonist
—> major effect is increased TPR (increased DBP + increased MAP)
some increase in HR via beta1 + some decrease in HR via reflex bradycardia = no change in HR
CO usually increases via beta1 (rise in SBP)
describe the effects of isoproterenol on heart function (CO, HR, MAP)
beta1 and beta2 agonist
—> increase HR, CO, and SBP via beta1
—> decrease MAP via beta2 (lower DBP + reflex tachycardia)
lower DBP + higher SBP = increase in pulse pressure (difference between)
describe the effects of phenylephrine on heart function (CO, HR, MAP)
alpha1 and alpha2 agonist
vasoconstriction via alpha1 —> increased TPR (increased DBP + MAP)
—> reflex bradycardia
more afterload —> decrease CO
so overall: lower CO, lower HR, INCREASE MAP
Drug A = increase HR + increase MAP
Drug A + Drug B = increase HR + decrease MAP
what are drug A and B?
Drug A = epinephrine - agonist of beta1, beta2, alpha1
Drug B = phenoxybenzamine - blocks alpha1
therefore, beta2 effects dominate, lowering BP
this is called “epinephrine reversal”
Drug A = decrease HR + increase MAP
Drug A + B = no change (neutral) HR and MAP
what are drug A and B?
Drug A = phenylephrine - alpha1 agonist causes increase in MAP and reflex bradycardia
Drug B = phenoxybenzamine - alpha1 blocker, reverses the effects of phenylephrine
