Pharmacology: Adrenergic Agonist/Blocking & Cholinergic Agonist/Blocking Drugs

Which drug is a direct-acting sympathomimetic? a. Epinephrine b. Amphetamine c. Ephedrine d. Albuterol

a Rationale: A direct-acting sympathomimetic binds directly to the receptor and causes a physiologic response. Epinephrine is an example of a direct-acting sympathomimetic. An indirect-acting sympathomimetic causes the release of the catecholamine from the storage sites (vesicles) in the nerve endings; it then binds to the receptors and causes a physiologic response. Amphetamine and other related anorexiants are examples of indirect-acting drugs. A mixed-acting sympathomimetic both directly stimulates the receptor by binding to and indirectly stimulates the receptor by causing the release of the neurotransmitter stored in vesicles at the nerve endings. Ephedrine is an example of a mixed-acting adrenergic drug. Noncatecholamine adrenergic drugs such as phenylephrine, metaproterenol, and albuterol are structurally dissimilar to the endogenous catecholamines and have a longer duration of action than either the endogenous or synthetic catecholamines. The noncatecholamine drugs show similar patterns of activity.

Which adrenergic-blocking drugs block only the betal-receptors on the surface of the heart? a. Cardioselective betal-blockers b. Nonselective beta-blockers c. Beta-2-blockers d. Alpha-blockers

a Rationale: Beta-blockers that are selective for receptors located in the heart are called cardioselective beta-blockers or beta-1-blocking drugs. Cardioselective betal-blockers block the betal-receptors on the surface of the heart. Other beta-blockers inhibit both beta-1- and beta-2-adrenergic receptors and are referred to as nonselective beta-blockers. Beta-2-receptors are located primarily on the smooth muscles of the bronchioles and blood vessels. The alpha-adrenergic-blocking drugs, or alpha-blockers, interrupt stimulation of the sympathetic nervous system at the alphal-adrenergic receptors.

Which alpha-blocker is beneficial in the treatment of frostbite? a. Phenoxybenzamine b. Phentolamine c. Tamsulosin d. Propranolol

a Rationale: Phenoxybenzamine is an alpha-blocker that is beneficial in the treatment of frostbite (and other conditions), in which patients have increased endogenous alpha -ad renergic agonist activity, which results in vasoconstriction. Phentolamine (Regitine) is an alpha-blocker that reduces peripheral vascular resistance and is also used to treat hypertension. Tamsulosin (Flomax), also an alpha-blocker, is used primarily to treat benign prostatic hyperplasia and is indicated for male patients. Propranolol (Inderal) is the prototypical nonselective beta-1-and beta-2-blocking drug.

Which time range specifies the peak plasma concentration of sotalol? a. 2.5 to 4 hours b. 2 to 4 hours c. 3 to 6 hours d. 6 to 20 hours

a Rationale: Sotalol (Betapace) is nonselective beta-blocker that has very potent antidysrhythmic properties. Sotalol is available only for oral use, and its peak plasma concentration is 2.5 to 4 hours. Propranolol's peak plasma concentration is 2 to 4 hours for the intravenous route, 3 to 6 hours for the immediate-release oral formulation, and 6 to 20 hours for the extended-release oral formulation.

Which effect happens when beta blockers are coadministered with anticholinergics? a. Reduced beta-blocker effect b. Increased blood glucose levels c. Enhanced effect of anticholinergics d. Prolonged neuromuscular blockade

a Rationale: When beta blockers are coadministered with anticholinergics, antagonism occurs, leading to a reduced beta-blocker effect. Anticholinergics do not affect blood glucose levels. Beta blockers do not enhance the effect of anticholinergics. A prolonged neuromuscular blockade occurs when beta blockers interact with neuromuscular blocking drugs.

Where are beta-2-adrenergic receptors located in the body? Select all that apply. One, some, or all responses may be correct. a. Arterioles b. Bronchioles c. Visceral organs d. Bladder sphincter e. Pupillary muscles of the iris

a, b, c Rationale: Beta-2-adrenergic receptors are located in the arterioles, the smooth muscles of the bronchioles, and the visceral organs. Alphal receptors are located in the bladder sphincter and pupillary muscles of the iris.

Which is an example of endogenous catecholamines? Select all that apply. One, some, or all responses may be correct. a. Dopamine b. Epinephrine c. Dobutamine d. Phenylephrine e. Norepinephrine

a, b, e Rationale: Dopamine, epinephrine, and norepinephrine are endogenous catecholamines that are synthesized in the body. Dobutamine and phenylephrine are synthetic catecholamines that are administered into the body to treat disorders caused by the deficiency of endogenous catecholamines.

Which adrenergic receptors are primarily located in the heart? a. Alpha-1 b. Beta-1 c. Alpha-2 d. Beta-2

b Rationale: Adrenergic receptors are divided into alpha-adrenergic receptors and beta-adrenergic receptors, depending on the specific physiologic responses caused by their stimulation. Both types of adrenergic receptors have subtypes, designated 1 and 2, which control stimulation and blockade, vasoconstriction and vasodilation of blood vessels, and the increased and decreased production of various substances. The beta-adrenergic receptors are all located on postsynaptic effector cells. The betal-adrenergic receptors are primarily located in the heart. The alpha-1-adrenergic receptors are located on postsynaptic effector cells—the tissue, muscle, or organ that the nerve stimulates. The alpha-2-adrenergic receptors are located on the presynaptic nerve terminals. They control the release of neurotransmitters. The predominant alpha-adrenergic agonist response is vasoconstriction and central nervous system stimulation. The beta-2-adrenergic receptors are located in smooth muscle fibers of the bronchioles, arterioles, and visceral organs. A beta-adrenergic agonist response results in bronchial, gastrointestinal, and uterine smooth muscle relaxation, glycogenolysis, and cardiac stimulation.

Which black box warning is shared for beta-blockers? a. May cause tachycardia b. Should not be withdrawn abruptly but tapered over 1 to 2 weeks c. Accelerated recovery from hypoglycemia in patients with type 1 diabetes d. May cause diarrhea

b Rationale: All beta-blockers share a black box warning stating that therapy should not be withdrawn abruptly but should be tapered over 1 to 2 weeks. Nonselective beta-blockers are known to mask symptoms of tachycardia. Sudden withdrawal may exacerbate underlying angina, precipitate a myocardial infarction, or cause rebound hypertension. Beta-blockers also delay recovery from hypoglycemia in patients with type 1 diabetes. The most common adverse effects of beta-blockers include bradycardia, depression, impotence, constipation, and fatigue; diarrhea is not a side effect.

During a cardiopulmonary resuscitation emergency, the nurse expects to administer which injectable, fast-acting medication? a. Salmeterol b. Epinephrine c. Naphazoline d. Oxymetazoline

b Rationale: Epinephrine is administered in emergency situations and is one of the primary vasoactive drugs used in many advanced cardiac life-support protocols. Naphazoline and oxymetazoline are administered intranasally to ease congestion. Naphazoline may also be used as an ophthalmic medication. Salmeterol is given via the respiratory tract because of its affinity for beta-2 receptors that act on the lungs.

Drugs in which class may interact with adrenergic drugs? a. Opioids b. Thyroid preparations c. Non-steroidal anti-inflammatory drugs d. Selective serotonin reuptake inhibitors

b Rationale: Thyroid preparations can increase the effects of adrenergic drugs. Opioids, selective serotonin reuptake inhibitors, and nonsteroidal antiinflammatory drugs do not have reported interactions with adrenergic drugs.

Which condition is an absolute contraindication to taking beta blockers? a. Pregnancy b. Heart failure c. Drug allergy d. Raynaud's disease

c Rationale: A drug allergy is an absolute contraindication due to the risk of anaphylaxis. Pregnancy, heart failure, and Raynaud's disease are not absolute contraindications but may be contraindications depending on the degree of symptoms due to the condition.

Which assessment would be completed prior to administering an adrenergic agonist? a. Skin integrity b. Temperature c. Blood pressure d. Respiratory rate

c Rationale: An adrenergic agonist causes vasoconstriction, leading to high blood pressure. Blood pressure is the most important assessment because of the detrimental effects of high blood pressure, such as stroke, which can be life threatening. Skin integrity, temperature, and respiratory rate are not directly affected by adrenergic agonists.

Which response is elicited by the activation of betal receptors located on the sinoatrial node? a. Vasodilation b. Vasoconstriction c. Increased heart rate d. Increased contractility

c Rationale: Increased heart rate is the response elicited by the activation of beta receptors located on the sinoatrial node. Vasodilation is a response elicited by the activation of beta-2 receptors located on the blood vessels. Vasoconstriction is a response elicited by the activation of alpha-1 receptors located on the blood vessels. Increased contractility is a response elicited by the activation of beta-1 receptors of the cardiac muscle.

Which route is used to administer tamsulosin? a. Intravenous b. Intradermal c. Oral d. Subcutaneous

c Rationale: Tamsulosin is an alpha-blocker used primarily to treat benign prostatic hyperplasia and is available only for oral use. Phentolamine, also an alpha-blocker, reduces peripheral vascular resistance and treats hypertension; it is available for intravenous, intradermal, and subcutaneous injection.

Which primary location are the betal-adrenergic receptors found in? a. Muscle b. Tissue c. Heart d. Blood vessel

c Rationale: The beta-1-adrenergic receptors are located primarily in the heart. The alphal-adrenergic receptors are located on the tissue, muscle, or organ that a nerve is stimulating. The beta-2-adrenergic receptors are located primarily on the smooth muscles of the bronchioles and blood vessels.

The patient is prescribed a beta-blocker medication and takes it with an aluminum hydroxide- type antacid at the evening meal. This regimen will result in which interaction? a. Increased beta-blocker activity b. Increased effect of the antacid c. Decreased beta-blocker activity d. Decreased effect of the antacid

c Rationale: The interaction of a beta blocker and an aluminum hydroxide antacid is likely to result in a decrease in the activity of the beta-blocker medication.

Which effect is a result of betal-adrenergic-receptor stimulation? a. Mydriasis b. Ejaculation c. Vasoconstriction d. Increased renin secretion

d Rationale: Beta-1-adrenergic-receptor stimulation causes increased renin secretion. Mydriasis, ejaculation, and vasoconstriction are the result of alphal-adrenergic-receptor stimulation.

Which effect may be seen when adrenergic drugs are administered with monoamine oxidase inhibitors (MAOIs)? a. Reduced therapeutic effects b. Increased risk for cardiac dysrhythmias c. Increased effects of adrenergic drugs d. Increased risk of hypertensive crisis

d Rationale: Numerous drug interactions can occur with adrenergic drugs. Administration of adrenergic drugs with MAOIs may cause a possibly life-threatening hypertensive crisis. When alpha- and beta-adrenergic drugs are given with adrenergic antagonists, such as some classes of antihypertensive drugs, the drugs directly antagonize each other, resulting in reduced therapeutic effects. Administration of adrenergics with anesthetic drugs may increase the risk for cardiac dysrhythmias. Antihistamines and thyroid preparations can also increase the effects of adrenergic drugs.

Which adrenergic-blocking drug is used for treating persistent migraines? a. Esmolol b. Carvedilol c. Metoprolol d. Propranolol

d Rationale: Propranolol is used to treat migraines. Esmolol is a very strong short-acting betal blocker. It is primarily used in acute situations to provide rapid, temporary control of the ventricular rate in patients with supraventricular tachydysrhythmias. Carvedilol has many effects, including acting as a nonselective beta blocker, an alphal blocker, a calcium channel blocker, and possibly an antioxidant. It is used primarily in the treatment of heart failure but is also beneficial for hypertension and angina. Metoprolol is a commonly used betal blocker that increases survival in patients who have experienced a myocardial infarction.