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51 Cards in this Set

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18 Pharm Adrenergic drugs III
Question
Answer
What is a noncompetitive (irreversible )alpha receptor antagonist?
Phenoxybenzamine
FIB: Phenoxybenzamine has a ___ onset but _________ duration of action.
slow onset, but a prolonged duration of action.
What is the effect of phenoxygenzamine on TPR and, by reflex, on HR and CO?
Decreases TPR (because it covalently binds to alpha receptors) and by reflex increases HR and CO (for homeostasis maintenance)
What is a nonselective, reversible alpha receptor antagonist which blocks both alpha1 and alpha2 receptors?
Phentolamine
What is the effect of phentolamine (Regitine) on TPR?
Decreases TPR (because it reversibly binds to alpha receptors) and by reflex increases HR and CO (for homeostasis maintenance)
If epinephrine (alpha and beta agonist) is administered along with phentoalmine what is the dominant effect?
Beta1 and beta2 because alpha1 and alpha2 is reversibly bound by the phentolamine
FIB: With phentolamine the blockade of a2 autoreceptors increases the release of ___ by adrenergic nerve terminals (in the heart, the increased release of ___ exacerbates the effects of reflex sympathetic cardiac stimulation)?
NE
If norepinephrine, a1, a2, b1 but little b2 (moderate dose) is administered along with phentolamine what is the dominant effect?
Beta1 because alpha1,2 is reversibly bound by the phentolamine
What is the effect of the a2 autoreceptor on adrenergic nerve terminals?
Negative regulation; by blocking this autoreceptor, the feedback is reduced and more NE is released
What is a selective alpha1 recepor antagonist with little (if any) blocakde of presynaptic alpha2 receptors?
Prazosin (minipress)
Terazosin, doxazosin, tamsulosin are all similar agents to what selective alph1 receptor antagonist?
Prazosin (minipress)
Why is their less reflex cardiac stimulation and greater antihypertensive efficacy than nonselective alpha1 and alpha2 receptor blockers?
No antagonism of a2 autoreceptors, so with prazosin does not inhibit the negative feedback loop resulting in 'normal' amount of NE released at the adrengergic nerve terminal
Hypertension, pheochromocytoma, benign prostatic hyperplasia, peripheral vascular disease, erectile dysfunction are all treated with what type of a receptor antagonist?
Alpha
What are the four side effects and precautions associated with alpha receptor antagonists?
Postural hypotension, nasal stuffiness (due to increased peripheral blood flow), reflex cardiac stimulation, impaired ejaculation
What mechanism is responsible for the reflex cardiac stimulation with an alpha receptor antagonist?
Since peripheral resistance is decreased (due to alpha receptor antagonism), HR & CO must increase to homeostatically compensate
Why is ejaculation potentially impaired as a side effect of alpha receptor antagonist?
Norepinephrine is involved in ejaculation
Name the three beta receptor antagonists.
Propranolol, atenolol, pindolol
What is the nonselective beta receptor antagonist without intrinsic sympathomimetic activity?
Propranolol
What is the beta1 selective agent with out intrinsic sympathomimetic activity?
Atenolol (tenormin)
What are the three effects of propanolol on HR, MCF, and CO?
Decreased (due to b1,b2, b3 effects0
What is the effect of propanolol effects on conduction velocity?
Decreased (due to b1,b2, b3 effects0
What is the effect of propanolol on myocardial oxygen demand?
Decreased (due to reduced cardiac activity)
What is the effect of propanolol on spontaneous rate of depolarization
Decreased
What is the two vascular/BP effects on propanolol?
Decreased TPR and Decreased plasma renin
Describe how HTN patients' BP is effected by propanolol?
Delayed fall, but a net reduction in BP.
T/F: In normal patients propanolol has what effect on plasma glucose?
No effect (but in diatbetics it does slow the recovery of plasma glucose levels afte rinsulin administration to diabetics patients.
What is the effect of propanolol on VLDL, HDL, and LDL?
Increased VLDL, Decrease in HDL, and no change in LDL
What is the effect on propanolol on brnochioles?
Increased airway resistance (due to beta 2 blockade (bronchoconstriction)
T/F: Atenolol has similar cardiovascular effects are similar to those seen with propranolol.
TRUE
FIB: Bronchoconstriction is less of a problem with atenolol (vs. propranolol) than with ___________ beta blockers.
nonselective
List five cardiac therapeutic uses of beta receptor antagonists.
HTN, Ischemic heart disease, cardiac arrhythmias, obstructive cardiomyopathy, Congestive heart failure
List three non cardiac therapeutic uses of beta receptor antagonists?
Open angle glaucoma (decreased production of aqueous humor), migraine headache prophylaxis, tremor (performance anxiety)
What is the effect of beta blockers on mortality in CHF?
Can prolong life
List five cardiac side effects of beta blockers.
Bradycardia, A-V block, cardiac arrest, cardiac failure, IHD symptoms
What is the effect of beta blockers as a side effect on airways?
Bronchoconstriction
Describe potential side/adverse effects on lipids?
Increase in adverse plasma trigylcerides
Describe potential side/adverse effects of beta blockers on CNS/Exercise?
Decrease in performance, CNS depression
Name a selective alpha1 and nonselective beta blockers, aka mixed antagonists?
Labetalol (normodyne), carvedilol (coreg)
Mixed antagonists (Coreg, Labetalol) are used in the treatment of what three HTN and what symptom of IHD?
HTN, HTN emergencies, pheochromocytoma-induced HTN and angina pectoris
Name an adrenergic neruon blocking agents which interfere with chemical mediation at post-ganglionic adrenergic nerve endings)?
Guanethidine (Ismelin)
What is transported into noradrenergic nerve terminals by the same neuronal membrane transporter which is responsible for the reuptake of NE.
Guanethidine (Ismelin)
What drug prevents the action potential-induced release of NE (probably via membrane stabilizing effect)?
Guanethidine (Ismelin)
T/F: Guanethidine does not penetrate the BBB and does not affect the adrenal medulla.
TRUE
Guanethidine treats what condition?
HTN
Postural hypotension, hypotension, fuluid retention, impaired ability to ejaculate, and increase in GI motility (diarrhea) secondary to NE absence at the terminal adrenergic nerve terminals are side effects of what drug?
Guanethidine (Ismelin)
What is the site of action of Clonidine on CNS alpha2 receptors to reduce activity in central sympathetic outlflow?
Medulla oblongata (Vasomotor center in the ventrolateral reticular formation) and Nucleus of the solitary tract (NTS)
How does Clonidine cardiovascular actions on MAP, HR, and CO?
Clonidine is a CNS a2 receptor agonist which causes a reduction in activity in the central sympathetic outlfow resulting in decrease in MAP, HR, and CO
What is the indicated use of Clonidine?
antihypertensive agent
Sedation, mental lassitude, dry mouth, and rebound htn with abrupt withdrawal is the side effect profile of which CNS alpha2 receptor agonist?
Cloniditne (Catapres)