Adrenergic Agonists & Antagonists Flashcards
What is the primary clinical indication for Isoproterenol?
Patients with heart block
What ADR is associated with high doses of a Beta2 agonist?
Tremors due to stimulation of Beta2 receptors on skeletal muscle
What serious effect is associated with the abrupt discontinuance of beta blockers?
Heart arrhythmias
Dopamine is the drug of choice for the treatment of shock. Why is this?
Stimulates D1, beta, and alpha receptors - increases CO & BP while still maintaining adequate perfusion of important organs, such as the kidney, gut, and heart
What alpha1 blocker is most effective for BPH (benign prostatic hyperplasia) and not hypertension?
Tamsulosin
What drug is a Beta1 agonist?
Dobutamine
True/False. Drugs that stimulate Beta and Alpha receptors always stimulate Beta receptors first.
True. Beta receptors are first activated followed by alpha receptors, depending upon the drug dose. Dopamine receptors would be activated before beta receptors in a drug that stimulates all receptors.
A patient experiences hypertension due to a high epinephrine dose. An alpha1 blocker is administered. What is the ultimate effect on BP?
BP will decrease significantly and the patient will become hypotensive. This is because epinephrine also stimulates Beta receptors causing vasodilation and decreased TPR. This response is called epinephrine reversal
Prazosin, doxazosin, and tamsulosin are why types of drugs?
Selective alpha1 blockers
What is the MOA for beta blockers that have anesthetic effects?
Block Na+ channels to stabilize the cell membrane
What drug acts as a non-selective Beta agonist?
Isoproterenol
Alpha 2 antagonists are clinically indicated for the treatment of…?
Hypertension, withdrawal symptoms from opiates, tobacco, benzodiazepines
What catecholamine is contraindicated in patients with a sulfur allergy?
Isoproterenol
Postural hypotension is associated with blockage of what receptors?
Alpha1
What drugs belong to the non-selective beta agonists class?
Epinephrine & isoproterenol
True/False. Albuterol is used as a long-term bronchodilator for asthma treatment.
False. Albuterol is a short-term bronchodilator
Dobutamine is preferred in patients with acute heart failure. Why is this?
It increases CO without increasing contractility so O2 demand of the heart is not increased
What is the effect of Beta2 stimulation on blood vessels?
Vasodilation, decreased TPR, decreased BP
What beta-blockers can cross the BBB?
Propranolol & Carvedilol
What is the effect of NE on HR?
Reflex bradycardia due to increased BP and TPR
What is the effect of Beta2 stimulation on blood glucose?
Beta2 stimulation promotes glycogenolysis and increases blood glucose
At therapeutic doses, NE preferentially stimulates what receptors?
Alpha receptors more than beta receptors
What Beta blockers have partial agonist activity?
Pindolol & acebutolol
Stimulation of what receptor causes contraction of the bladder and promotes urine retention?
Alpha1
What adrenergic neurotransmitter is released at organs innervated by the SANS?
NE
What two drugs are mixed adrenergic agonists?
Ephedrine & pseudophedrine
What class of adrenergic drug is indicated for the treatment of an overactive bladder?
Beta3 agonist (Mirabegron)
Where are D2 receptors located?
CNS
What beta-blocker can be used to treat glaucoma?
Nadolol - no anesthetic effects
What drug acts on the adrenergic synapse to block NE synthesis?
Metyrosine
What is the suffix for all beta blockers?
-olol
Alpha1 receptors have what effects on the eye?
Mydriasis (pupil dilation) and increased ocular pressure
What drug acts on the adrenergic synapse to block NE storage?
Reserpine
What are the non-selective alpha-blockers?
Phenoxybenzamine & Phentolamine
What drug selectively stimulates D1 receptors?
Fenoldopam
What is the effect of Beta1 stimulation on the heart?
Increased HR, increased contraction, increased CO
What adrenergic agonist is used to treat patients in septic shock?
NE to increase BP quickly
A woman is experiencing premature labor and needs to be transferred to a facility with a NICU. What drug may be administered to inhibit uterine contractions during transportation?
Beta2 agonist - Terbutaline
What is the effect of Beta2 stimulation on the lungs?
Bronchodilation
What receptors are stimulated to suppress premature labor in women?
Beta2
What is the difference between direct and indirect adrenergic agonists?
Direct agonists bind directly to the receptor. Indirect agonists indirectly increase NE at the synapse by promoting release, inhibiting reupdate, and/or inhibiting degradation
Activation of D1 receptors has what effect on blood vessels?
Vasodilation
Use of an alpha1 antagonist may have what effect on male ejaculation?
Inhibited ejaculation
Nebivolol belongs to what drug class?
Beta1 blocker
True/False. Epinephrine is non-selective for alpha and beta receptors.
True. However, since epinephrine stimulates both, beta receptors will be stimulated before alpha receptors at low doses.
What drugs act as indirect adrenergic agonists?
Cocaine, TCA, amphetamines, tyramine
What is the MOA of cocaine on the adrenergic synapse?
Prevents NE reuptake
True/False. Catecholamines are used primarily in outpatient settings.
False. Catecholamines are extremely potent and fast acting. They must also be given via IV. As such they are used only in emergencies.
Non-catecholamines have a longer 1/2 life and are by PO administration. They are used in outpatient settings.
What are the two classifications of direct-acting adrenergic agonists?
Catecholamines & Non-catecholamines
What is the primary function of Alpha2 receptors?
Autoreceptors that decrease NE
What are the short-acting Beta2 agonists?
Albuterol & Terbutaline
What drug acts on the adrenergic synapse to block NE release?
Guanethidine
Alpha1 receptors have what effects on blood vessels?
Vasoconstriction, increased TPR, increased BP
What adrenergic receptors are always stimulatory?
Alpha1 & Beta1
Alpha2 receptors are located where?
On pre-synaptic neurons to decrease NE
Where are most Beta1 receptors located?
Heart
What is the general effect of Isoproterenol on BP?
Decrease - HR & CO increase due to Beta1 stimulation, but blood vessels dilate and TPR decreases due to Beta2 stimulation
What is the primary method in which NE is removed from the synaptic cleft?
Active reuptake into the pre-synaptic neuron
What is the primary difference between Phenoxybenzamine & Phentolamine?
Phenoxybenzamine is long-acting and irreversible. Phentolamine is short-acting and reversible
What adrenergic receptors are always inhibitory?
Alpha2 & Beta2
This molecule is found in picked and fermented food and increases release of NE.
Tyramine
Why is rebound hypertension possible with abrupt discontinuance of alpha2 agonists?
Alpha2 agonists decrease NE. As a result, post-synaptic neurons upregulate their receptors. When alpha2 agonists are discontinued rapidly, normal release of NE on more receptors will cause hypertension and other symptoms
What is the MOA of amphetamines on the adrenergic synapse?
Increases NE release and decreases uptake
What neurotransmitter is primarily released on Beta2 receptors?
Epinephrine
True/False. Non-selective alpha agonists should never be used in the eye or nose.
False. They should ONLY be used in the eye and nose. Systemic use will cause severe hypertension and ADRs
What are the clinical uses of epinephrine?
Anaphylactic shock, cardiac arrest, asthma attack
What type of adrenergic receptor exists on the pre-synaptic neuron and serves as an autoreceptor to decrease NE release?
Alpha2 - activated when NE concentrations in the synaptic cleft are very high
What effect do beta blockers have on blood glucose that is an important consideration in diabetic patients?
Can lead to hypoglycemia, but symptoms (tachycardia, tremors, etc.) may be masked
