Adrenergic Antagonist Continued Flashcards
Now starting off with beta 1 selective adrenergic antagonists are atenolol and metoprolol, what are they useful for?
- -Hypertensive patients with impaired pulmonary function
- -Diabetic HTN patients who are receiving insulin or oral hypoglycemic agents
What is the use for beta1 selective adrenergic antagonists?
- -Management of HTN
- -long term management of patients with angina
- -management of patients with acute MI to reduce cardiovascular mortality
What is a major adverse effect of beta adrenergic antagonism
-Blockade of beta2 receptors in bronchial smooth muscle
drugs with selectivity for beta1 receptors are somewhat less likely to induce bronchospasm, however, since the selectivity of current beta blockers for beta1 receptors is modest, these drugs should be avoided if at all possible in patients with asthma
Finally the last beta1 selective adrenergic antagonist is esmolol, what is its action
—Ultra short acting B1 selective adrenergic antagonist
continous infusions of esmolol, steady state concentrations are achieved quickly, and the therapeutic effects are terminated rapidly upon discontinuation of infusion
What are the uses for esmolol?
—Control supraventricular arrhythmias, arrhythmias associated with thyrotoxicosis, perioperative hypertension, and myocardial ischemia in acutely ill patients
Moving on to drugs that are alpha1 and beta blockers, the first is labetalol, what is the action of this drug?
Competitive antagonist at beta and alpha1 receptors
–more potent as a beta antagonist than as an alpha antagonist
The actions of labetalol on both alpha1 and beta receptors contribute to the fall in what?
fall in blood pressure observed in patients with hypertension
- -alpha1 receptor blockage leads to relaxation of arterial smooth muscle and vasodilation (particularly in the upright position)
- -beta1 blockage contributes to the fall in blood pressure, in part by blocking reflex sympathetic stimulation of the heart
What is the use of labetalol?
–HTN
available in oral form for therapy of chronic hypertension
What are the adverse effects of labetalol?
- Orthostatic hypotension and dizziness: associated with alpha1 blockade
- Hepatic injury
The second alpha1 and beta blocker is carvedilol, what is the action of this drug?
- -More potent as a beta antagonist than as an alpha antagonist
- -used in HTN and congestive heart failure
Finally the last drug is a partial agonist called pindolol, what is the action of this drug?
- Partial beta agonist that posses intrinsic sympathomimetic activity
- -produces smaller reduction in resting heart rate and blood pressure
- -used for management of HTN
The last section in this deck of cards are drugs that act presynaptically. The first drug is an inhibitor of norephinephrine synthesis, alpha-methyltyrosine (metyrosine), what is the action of this drug?
—Inhibits tyrosine hydroxylase, the enzyme that catalyzes the conversion of tyrosine to DOPA
What is metyrosine used for?
—As an adjuvant to phenoxybenzamine and other alpha adrenergic blockers for management of malignant pheochromocytoma
(last resort drug for pheo)
Finally there are two drugs that are inhibitors of norepinephrine storage, the first is Reserpine, what is the use?
- -Irreversible inhibitor of VMAT resulting in depletion of norepinephrine
- -HTN patients taking this drug show a gradual decrease in blood pressure and slowing of cardiac rate.
- -in the past, was used to treat HTN
The last drug for this card deck is tetrabenazine, which is an inhibitor of norepinephrine storage, explain its use
- –Reversible inhibitor of VMAT and cause presynaptic depletion of catecholamines
- -tx of chorea associated with huntington’s disease
