Adrenergics Flashcards
Phenylephrine
alpha-1 receptor agonist. It is used to dilate the
eye, as a nasal decongestant, to terminate episodes of paroxysmal atrial tachycardia (reflex), and to treat hypotension.
Methoxamine
alpha-1 agonist used to treat orthostatic hypotension and paroxysmal atrial tachycardia
Clonidine
alpha-2 agonist that acts centrally to decrease
sympathetic outflow and thereby decrease blood pressure. Analogues are used to treat glaucoma.
Dobutamine
activates primarily beta-1 receptors. Used to treat
cardiogenic shock, low cardiac output. It is primarily an inotrope.
Methyldopa
converted methylnorepinephrine centrally which then activates alpha-2 receptors centrally to decrease sympathetic out flow and decrease blood pressure
Albuterol, metaproterenol, salmeterol, terbutaline
are all beta-2 agonist and can be used to treat bronchospasm, COPD, and bronchitis.
Isoproterenol
non-specific beta one agonist. Not the agent of choice for any application, but has been used for bronchospasm, heart block, and arrhythmias.
Pseudoephedrine
Mixed acting sympathomimetic. decongestant
Ephedrine
release of norepinephrine and also directly stimulate receptors, in the periphery as well as in the CNS. It thus has mild stimulatory effects. It is a component of the herbal medication, Ma
Huang.
Cocaine
blocks norepinephrine reuptake leading to an increase in norepinephrine and sympathetic responses. In the CNS, it has a profound stimulatory effect by blocking the reuptake of dopamine.
Amphetamine
substrate for the norepinephrine transporter; it then enters the vesicles, displacing norepinephrine, which then exits the presynaptic terminal via reversal of the transporter. This drug and its analogues are stimulants. They are used to treat attention deficit hyperactivity disorder.
Phenoxybenzamine
irreversible non-selective antagonist which will reduce blood pressure when sympathetic tone is high such as in patients with pheochromocytoma. Its primary adverse effect is tachycardia, due to blockade of presynaptic alpha2 receptors and reflex mechanisms.
Phentolamine
competitive antagonist at both alpha-1 and alpha-2 receptors. Its primary adverse effect is tachycardia, due to blockade of
presynaptic alpha2 receptors and reflex mechanisms.
Prazosin
alpha1 receptors, therefore, it is less likely to cause tachycardia than phentolamine.
Terazosin, Doxazosin
alpha1 selective antagonists
Tamsulosin
alpha1A and 1D antagonist that is thought to predominate in
the prostate.
Yohimbine
alpha 2 receptor antagonist
Tx Pheochromocytoma
Phenoxybenzamine
Tx for Chronic hypertension
apha1 antagonists such prazosin are used, but generally are not used alone, because other classes of drugs are known to be efficacious in heart failure. The major side effect is orthostatic hypotension which is more likely to occur after the first few doses. Palpitation can occur.
Tx for Peripheral vascular disease
occasionally prazosin or phenoxybenzamine are used to treat vasospasm in the peripheral circulation (Raynaud’s phenomenon), but other agents such as calcium channel blockers are preferred. Behavioral modifications should be tried first.
Urinary obstruction
Benign prostatic hyperplasia is common in older men and
can be treated with alpa-1 antagonists such as prazosin, doxazosin, and terazosin. Tamsulosin is more selective for the receptors in the prostate and therefore, it has relatively little effect on blood pressure and can be used in patients who have had a problem with orthostatic hypotension.
Erectile dysfunction
phentolamine is used as part of mixture that is injected into the penis, that facilitates erection in patients that have erectile dysfunction.
Propranolol
B-blocker Non-selective Highest lipid solubility; highest anesthetic action (MSA)
Timolol
B-blocker Non-selective Glaucoma (widely used), HPTN, MI
Nadolol
B-blocker. Non-selective Long-lasting (24hr)
Hypertension, angina
Atenolol
Beta-1- selective Lowest lipid solub.
Hypertension (widely used)
Metoprolol
Beta-1-selective High lipid solub (MSA)
Hypertension (widely used), angina, MI
Esmolol
Beta-1-selective Very short acting (10min)
Intraoperative and postoperative hypertension, arryhthmias
Pindolol
Non-selective partial agonist (ISA) (MSA)
Hypertension (brady/peripheral vascular disease)
Acebutolol
Hypertension (brady)
Labetolol
Non-selective for beta (some ISA at beta-2) Also blocks alpha-1
Severe hypertension
Carvedilol
Non-selective for beta (Also mild alpha-1 block)
CHF/hypertension
clinical uses of beta adrenergic antagonists
Hypertension, ischemic heart disease, arrhythmia, heart failure, glaucoma, migraine, hyperthyroidism, performance anxiety
Tyramine
component of some foods that is normally rapidly metabolized by monoamine oxidase in the liver and GI tract. Caution with MAOi use. The action of tyramine is similar to amphetamine. It can cause a hypertensive crisis, by releasing large amounts of norepinephrine.
