Peripheral Nervous System Drugs Ch. 12-19 (TB) Flashcards
A patient receives morphine and shows signs of toxicity. The prescriber orders naloxone (Narcan) to reverse the effects of the morphine. The nurse understands that the naloxone works at the same receptor sites as the morphine to: a. block transmitter reuptake. b. inhibit transmitter release. c. interfere with transmitter storage. d. prevent activation of receptors.
D
Morphine and its antagonist, naloxone, both act directly at the same receptors. Morphine causes activation, and naloxone prevents activation. Neither morphine nor naloxone acts to alter transmitter reuptake, release, or storage.
A nurse is teaching a group of nursing students about neuropharmacology. Which statement by a student about peripheral nervous system (PNS) drugs indicates a need for further teaching?
a.
“Drugs affecting axonal conduction have a variety of uses.”
b.
“Drugs that alter synaptic transmission can be highly selective.”
c.
“Many PNS drugs act by altering synaptic transmission.”
d.
“These drugs work by influencing receptor activity.”
A
Local anesthetics are the only drugs shown to work by altering axonal conduction. Any drug affecting axonal conduction would be nonselective, because axonal conduction of impulses is essentially the same in all neurons. In contrast, drugs that affect synaptic transmission can be highly selective, because each transmitter has different effects on receptor sites. Most PNS drugs work on synaptic transmission processes. Through their effects on transmitters, they influence receptor activity.
A nurse is teaching a group of nurses about neuropharmacology. The nurse asks which classes of drugs act by reducing axonal conduction. Which response by a participant is correct? a. Antihypertensives b. Antipsychotics c. Local anesthetics d. Antidepressants
C
Local anesthetics are the only drugs shown to work by reducing axonal conduction. Antihypertensives, antipsychotics, and antidepressants do not act by reducing axonal conduction.
A nurse is administering drug X to a patient. The drug information states that the drug acts by activating receptors in the peripheral nervous system by increasing transmitter synthesis. The nurse understands that the effect of this drug is to: a. activate axonal conduction. b. enhance transmitter storage. c. increase receptor activation. d. synthesize supertransmitters.
C
Drugs that increase transmitter synthesis increase receptor activation. Other drugs that alter transmitter synthesis can decrease synthesis and would cause decreased receptor activation. Drugs that affect transmitter production do not exert their effects on axonal conduction. The amount of transmitter produced does not directly affect transmitter storage. Some drugs that alter transmitter synthesis cause the synthesis of transmitter molecules that are more effective than the transmitter itself.
A nurse learns about a drug that interferes with transmitter storage in the PNS. The transmitter affected by this drug causes an increased heart rate. What response will the nurse expect to see when this drug is administered? a. Bradycardia b. Positive inotropic effects c. Prolonged receptor activation d. Tachycardia
A
Drugs that interfere with transmitter storage reduce receptor activation, because disruption of storage decreases the amount of transmitter available for release. Because this transmitter increases the heart rate, the result will be a decrease in the heart rate. Inotropic effects control the force of contraction, not the rate of contraction. Decreased transmitter storage would result in decreased receptor activation. Tachycardia would occur if transmitter availability were increased.
A patient receiving botulinum toxin injections to control muscle spasticity asks how the drug works. The nurse knows that this drug affects the transmitter acetylcholine by: a. inhibiting its release. b. interfering with its storage. c. preventing its reuptake. d. promoting its synthesis.
A
Acetylcholine is a neurotransmitter that activates receptors that increase skeletal muscle contraction. Botulinum toxin inhibits the release of this transmitter. It does not interfere with storage, reuptake, or synthesis of acetylcholine.
A patient has allergies and takes an antihistamine. The patient wants to know how the drug works. The nurse understands that antihistamines work because they are what? a. Activators b. Agonists c. Antagonists d. Antidotes
C
Antihistamines bind to receptors to prevent activation by histamine; this makes antihistamines antagonist drugs. Antihistamines do not activate receptors. Agonist drugs activate receptors; they are not antidotes.
A nursing student asks about drugs that interfere with the termination of transmitter action. Which statement by the nurse is correct?
a.
“Drugs act on this process by altering the diffusion of the transmitter away from the synaptic gap.”
b.
“Drugs can interfere with termination by either increasing or decreasing reuptake of the transmitter.”
c.
“Drugs in this category lead to decreased activation by the transmitter in the synapse.”
d.
“These drugs reduce either reuptake or degradation of the transmitter, causing an increase in receptor activation.”
D
Drugs that interfere with termination of transmitter action do so by blocking transmitter reuptake or inhibiting transmitter degradation, resulting in increased receptor activation, because more of the transmitter remains available. Diffusion of the transmitter occurs naturally, but it is a slow process with little clinical significance. Drugs that alter this process cause a decrease in reuptake, not an increase. The effect of drugs that interfere with termination of transmitter action is increased activation.
The nurse understands that patients are given beta1 agonists to treat \_\_\_\_\_ failure. a. heart b. kidney c. respiratory d. liver
A
A beta1 agonist increases the patient’s heart rate and blood pressure and is used in heart failure. Beta1 agonists would not be used for kidney, respiratory, or liver failure.
A nurse is teaching a patient about a medication that alters sympathetic nervous system functions. To evaluate understanding, the nurse asks the patient to describe which functions the sympathetic nervous system regulates. Which answer indicates the need for further teaching? a. “The digestive functions of the body” b. “The cardiovascular system” c. “The fight-or-flight response” d. “Body temperature”
A
The sympathetic nervous system does not regulate digestive functions of the body—the parasympathetic nervous system does; further education is needed. The sympathetic nervous system regulates the cardiovascular system, the fight-or-flight response, and the body temperature; no further education is needed.
A patient is wheezing and short of breath. The nurse assesses a heart rate of 88 beats per minute, a respiratory rate of 24 breaths per minute, and a blood pressure of 124/78 mm Hg. The prescriber orders a nonspecific beta agonist medication. Besides evaluating the patient for a reduction in respiratory distress, the nurse will monitor for which side effect? a. Hypotension b. Tachycardia c. Tachypnea d. Urinary retention
B
Beta agonists are used for asthma because of their beta2 effects on bronchial smooth muscle, causing dilation. Beta1 effects cause tachycardia and hypertension. Beta receptors do not exert effects on the bladder.
A nurse is teaching a group of nursing students about neurotransmitters. Which statement by a student about acetylcholine indicates a need for further teaching?
a.
“It activates three cholinergic receptor subtypes.”
b.
“It has effects in the parasympathetic, sympathetic, and somatic nervous systems.”
c.
“It is used at most junctions of the peripheral nervous system.”
d.
“Its transmission is terminated by reuptake into the cholinergic nerve terminal.”
D Acetylcholine (ACh) is destroyed by acetylcholinesterase, an enzyme that degrades ACh into two inactive products: acetate and choline. Choline is taken up into the nerve terminal. ACh activates three receptor sites: nicotinicN, nicotinicM, and muscarinic. ACh has effects throughout the peripheral nervous system (PNS) and is used at most junctions in the PNS.
A nurse is administering an agonist drug that acts on postganglionic neurons of the sympathetic nervous system. Which response will the nurse expect to see? a. Decreased sweating b. Bronchodilation c. Increased cardiac output d. Pinpoint pupils
C Norepinephrine (NE) is the most common neurotransmitter released by all postganglionic neurons of the sympathetic nervous system except those going to sweat glands where ACh is the neurotransmitter. NE acts on alpha1, alpha2, and beta1 receptors to increase the force and rate of cardiac contraction, thus increasing cardiac output. ACh would increase sweating. Bronchodilation occurs when epinephrine activates beta2 receptors on bronchial smooth muscle. NE affects alpha1 receptors to dilate the pupils.
Many medications list side effects that include dry mouth, constipation, and urinary retention. What kind of effects are these? a. Alpha adrenergic b. Anticholinergic c. Beta adrenergic d. Sympathetic
B
Cholinergic stimulation by ACh causes increased salivation, increased gastrointestinal (GI) motility, and relaxation of the bladder trigone and sphincter. Anticholinergic medications inhibit these responses, causing dry mouth, constipation, and urinary retention. Alpha-adrenergic agents effect processes in the sympathetic nervous system, causing peripheral vasoconstriction and pupil dilation, among other effects. The effects of beta-adrenergic medications are seen mostly in the heart and blood vessels. The sympathetic nervous system has both cholinergic and adrenergic transmitters.
A nurse is explaining activation of beta2 receptors to some student nurses during a clinical rotation at the hospital. Which statement by a student demonstrates a need for further teaching?
a.
“Beta2 activation results in bronchodilation.”
b.
“Beta2 activation results in contraction of uterine muscle.”
c.
“Beta2 activation results in glycogenolysis.”
d.
“Beta2 activation results in vasodilation of skeletal muscles.”
B
Beta2 activation would result in relaxation of uterine smooth muscle, not contraction; this statement indicates a need for further teaching. Bronchodilation is an effect of beta2 activation; no further teaching is needed. Beta2 activation does result in glycogenolysis; no further teaching is needed. Beta2 activation does result in vasodilation of skeletal muscle; no further teaching is needed.
A pregnant patient is in premature labor. Which class of drug will she be given? a. Alpha1 agonist b. Anticholinergic c. Beta2 agonist d. Beta2 antagonist
C
Beta2 agonists cause relaxation of uterine muscle, slowing or stopping the contractions that precipitate labor. An alpha1 agonist would have effects on the heart and arterioles. Anticholinergic drugs generally are given for their effects on the urinary and GI tracts and do not affect uterine muscle. A beta2 antagonist would cause increased constriction of uterine muscle.
A patient is to receive a beta agonist. Before administration of this medication, which assessment finding would most concern the nurse? a. Pulse oximetry reading of 88% b. Blood pressure of 100/60 mm Hg c. Respiratory rate of 28 breaths per minute d. Heart rate of 110 beats per minute
D
A beta agonist dilates respiratory smooth muscle, but as a side effect, it can stimulate the heart. A heart rate of 110 beats per minute is a concern, because this medication may further increase the already elevated heart rate. A pulse oximetry reading of 88% is a concern, but the medication causes bronchodilation and increased oxygenation; this should increase the pulse oximetry reading. A blood pressure of 100/60 mm Hg is on the low side, but this medication may actually cause an increase in blood pressure as a side effect; this should not concern the nurse before administration of the medication. A respiratory rate of 28 breaths per minute is elevated; however, this medication should increase oxygenation by bronchodilation, and the patient’s respiratory rate should decrease once oxygenation has improved. Therefore, this should not concern the nurse.
A prescriber has ordered pilocarpine (Pilocar). A nurse understands that the drug stimulates muscarinic receptors and would expect the drug to have which action?
a.
Reduce excessive secretions in a postoperative patient
b.
Lower intraocular pressure in patients with glaucoma
c.
Inhibit muscular activity in the bladder
d.
Prevent hypertensive crisis
B
Pilocarpine is a muscarinic agonist used mainly for topical therapy of glaucoma to reduce intraocular pressure. Pilocarpine is not indicated for the treatment of excessive secretions and mucus; in fact, pilocarpine is used to treat dry mouth. Pilocarpine does not inhibit muscular activity in the bladder. Pilocarpine is not used to prevent hypertensive crisis.
A patient has developed muscarinic antagonist toxicity from ingestion of an unknown chemical. The nurse should prepare to administer which medication? a. Atropine (Sal-Tropine) IV b. Physostigmine (Antilirium) c. An acetylcholinesterase activator d. Pseudoephedrine (Ephedrine)
B
Physostigmine is indicated for muscarinic antagonist toxicity. Atropine is a drying agent and would only complicate the drying action that arises from the muscarinic antagonist. An acetylcholinesterase activator would only contribute to dryness that arises from the muscarinic antagonist. Ephedrine is not indicated for muscarinic antagonist toxicity.
A prescriber has ordered bethanechol (Urecholine) for a postoperative patient who has urinary retention. The nurse reviews the patient’s chart before giving the drug. Which part of the patient’s history would be a contraindication to using this drug? a. Asthma as a child b. Gastroesophageal reflux c. Hypertension d. Hypothyroidism
A
Bethanechol is contraindicated in patients with active or latent asthma, because activation of muscarinic receptors in the lungs causes bronchoconstriction. It increases the tone and motility of the gastrointestinal (GI) tract and is not contraindicated in patients with reflux. It causes vasodilation and would actually lower blood pressure in a hypertensive patient. It causes dysrhythmias in hyperthyroid patients.
A patient will begin using a transdermal preparation of a muscarinic antagonist for overactive bladder (OAB). The nurse teaches the patient what to do if side effects occur. Which statement by the patient indicates the need for further teaching?
a.
“I can use sugar-free gum for dry mouth.”
b.
“I may need laxatives for constipation.”
c.
“I should keep the site covered to prevent other people from getting the medicine.”
d.
“I will take Benadryl for any itching caused by a local reaction to the patch.”
D
Benadryl is an antihistamine, and even though it is not classified as a muscarinic antagonist, it has anticholinergic effects. Giving it with a muscarinic antagonist greatly enhances these effects, so it should not be used. Muscarinic antagonists cause dry mouth, and patients should be taught to use sugar-free gum or candies to help with this. Muscarinic antagonists can cause constipation, and laxatives may be used. Medication applied topically can be transferred to others who come in contact with the skin, so the site should be covered.
An older adult patient who lives alone and is somewhat forgetful has an overactive bladder and reports occasional constipation. Which treatment will the nurse anticipate for this patient?
a.
Behavioral therapy
b.
Oxybutynin (Ditropan XL) extended-release tablets
c.
Oxybutynin (Oxytrol) transdermal patch
d.
Percutaneous tibial nerve stimulation (PTNS)
C
The transdermal patch is applied weekly and may be the best option for a patient who is more likely to forget to take a daily medication. The transdermal preparation has fewer side effects than the systemic dose so is less likely to increase this patient’s constipation. Behavioral therapy should be tried first in patients who can participate. However, it is not the best option for a forgetful patient who lives alone, because it requires scheduled voiding and timing of fluid intake. The extended-release tablets must be given daily, and this patient may not remember to take them. PTNS is used after behavioral and drug therapies have failed.
A patient received atropine intravenously before surgery. The recovery room nurse notes that the patient is delirious upon awakening, has a heart rate of 96 beats per minute, a respiratory rate of 22 breaths per minute, and a blood pressure of 110/78 mm Hg. The nurse notifies the anesthesiologist, who will order:
a.
activated charcoal to minimize intestinal absorption of the antimuscarinic agent.
b.
an acetylcholinesterase inhibitor to compete with the antimuscarinic agent at receptors.
c.
an antipsychotic medication to treat the patient’s central nervous system symptoms.
d.
ipratropium bromide (Atrovent) to counter the respiratory effects of the antimuscarinic agent.
B
This patient is showing signs of antimuscarinic toxicity, caused by the atropine given during surgery. The most effective antidote is physostigmine, which inhibits acetylcholinesterase, allowing acetylcholine to build up at cholinergic junctions and compete with the antimuscarinic agent for receptor binding. Activated charcoal is only useful if an antimuscarinic agent has been ingested, because it impedes absorption from the GI tract. Because this patient’s psychotic symptoms are caused by an antimuscarinic agent, physostigmine should be given to treat the cause; an antipsychotic medication would only treat the symptom. Ipratropium bromide is an antimuscarinic agent and would only compound the effects. This patient’s respiratory rate is only mildly elevated.
Bethanechol (Urecholine) is used to treat urinary retention but is being investigated for use in which other condition? a. Gastric ulcers b. Gastroesophageal reflux c. Hypotension d. Intestinal obstruction
B
Bethanechol is being investigated for treatment for gastroesophageal reflux disease (GERD) because of its effects on esophageal motility and the lower esophageal sphincter. Bethanechol stimulates acid secretion and could intensify ulcer formation. Bethanechol can cause hypotension. Because bethanechol increases the motility and tone of intestinal smooth muscle, the presence of an obstruction could lead to bowel rupture.
A patient receives topical atropine to facilitate an eye examination. The nurse will tell the patient to remain in a darkened room or to wear sunglasses for several hours until the effects of the medication wear off. This teaching is based on the nurse’s knowledge that muscarinic antagonists cause: a. elevation of intraocular pressure. b. miosis and ciliary muscle contraction c. paralysis of the iris sphincter. d. relaxation of ciliary muscles.
C
By blocking muscarinic receptors in the eye, atropine causes paralysis of the iris sphincter, which prevents constriction of the pupil; consequently, the eye cannot adapt to bright light. This also causes an elevation in intraocular pressure, which increases the risk of glaucoma. However, it is not an indication for wearing darkened glasses. Muscarinic agonists cause miosis; atropine causes mydriasis. The effect of relaxing ciliary muscles focuses the eye for far vision, causing blurred vision.
A nurse is caring for a patient who has myasthenia gravis. The prescriber has ordered neostigmine (Prostigmin). An important initial nursing action before administration of the medication includes assessing: a. the ability to raise the eyelids. b. level of fatigue. c. skeletal muscle strength. d. swallowing ability.
D
Many patients hospitalized for myasthenia gravis do not have the muscle strength to swallow well and need a parenteral form of the medication; therefore, assessing the patient’s ability to swallow is an important initial safety measure. Evaluating the patient’s ability to raise the eyelids, level of fatigue, and skeletal muscle strength are all important assessments both before drug administration and during drug treatment, because they indicate the effectiveness of the drug and help determine subsequent doses.
A nurse working in the emergency department is assigned to a child who is arriving by ambulance after being involved in a spill of organophosphate insecticides. What will the nurse expect to be the initial priority for treating this child?
a.
Administering diphenhydramine to control secretions
b.
Giving diazepam to control seizures
c.
Providing mechanical ventilation and oxygen
d.
Reporting the spill to the Environmental Protection Agency
C
All of these courses of action may be part of the treatment. However, the initial concern is to prevent death from apnea caused by laryngospasm, bronchoconstriction, and paralysis leading to apnea; therefore, maintaining an airway is the most important consideration. Pralidoxime is the specific antidote and should be given next. Atropine is used to control secretions. Diazepam is given when seizures occur. Reporting the accident to the proper authorities is not a priority during a life-threatening emergency.
A patient who has myasthenia gravis will be taking neostigmine (Prostigmin). What will the nurse emphasize when teaching this patient about the medication?
a.
“Stop taking the drug if you have diarrhea.”
b.
“Take a supplementary dose before exercise.”
c.
“Use atropine if you have excessive salivation.”
d.
“Withhold the dose if ptosis occurs.”
B
Neostigmine doses must be adjusted continually, and patients usually need supplemental doses before exertion; therefore, patients must be taught how to modify doses as needed. Increased gastrointestinal (GI) secretions can cause loose stools; this is a known adverse effect that does not warrant stopping the drug. Atropine will help with excessive salivation but should not be used routinely, because it can mask the early signs of anticholinesterase overdose. Ptosis is one of the symptoms of myasthenia gravis and is an indication for taking neostigmine.
Two nurses are discussing the major differences between physostigmine (Antilirium) and neostigmine (Prostigmin). One nurse correctly makes which statement about physostigmine (Antilirium)?
a.
“It is not effective for treating poisoning by muscarinic blocking drugs.”
b.
“It can readily cross the blood-brain barrier.”
c.
“It does not cause any side effects.”
d.
“It can be given by all routes.”
B
The basic pharmacology of physostigmine is nearly identical to that of neostigmine, except that physostigmine readily crosses membranes, including the blood-brain barrier; neostigmine does not. Physostigmine and neostigmine are both effective for treating poisoning by muscarinic blocking drugs. Neither physostigmine nor neostigmine is devoid of side effects. Physostigmine can be given only intramuscularly (IM) or intravenously (IV); neostigmine is given orally (PO), IM, IV, and subcutaneously (subQ).
A nurse is helping a nursing student who is administering a medication to a patient with myasthenia gravis. Which statement by the student indicates the need for further teaching?
a.
“I will ask the patient to sip some water before giving the medication.”
b.
“I will let the patient sleep after giving the medication, because rest is important.”
c.
“I will record muscle strength assessments before and after I give the medication.”
d.
“I will report excessive salivation to the patient’s prescriber.”
B
An important assessment indicating the medication’s effectiveness is evaluating a patient’s ability to raise the eyelids. Letting the patient sleep, even though rest is important, would prevent the nurse from making this assessment. To make sure the patient can safely swallow a pill, the nurse must evaluate swallowing ability by asking the patient to take a sip of water. Muscle strength assessments before and after medication administration help the nurse evaluate the medication’s effectiveness. Excessive salivation may be a sign of drug toxicity and should be reported.
A patient with myasthenia gravis who is taking a cholinesterase inhibitor is being admitted to the intensive care unit and is on mechanical ventilation. The prescriber has ordered a challenge dose of edrophonium to distinguish between a myasthenic crisis and a medication overdose. The nurse will expect to do what?
a.
Administer neostigmine if muscle strength decreases.
b.
Be prepared to administer atropine if muscle weakness increases.
c.
Give a second dose of edrophonium if no improvement is seen.
d.
Give pralidoxime (Protopam) if cholinergic symptoms worsen.
B
Edrophonium is an ultra-short-acting cholinesterase inhibitor used to distinguish between a myasthenic crisis and a cholinesterase inhibitor overdose, because weakness or paralysis can occur with both. If the symptoms are intensified and muscle weakness increases, the crisis is cholinergic, meaning that the patient is having toxic effects from the cholinesterase inhibitor and needs atropine as an antidote. Neostigmine would be given if the patient shows improved muscle strength, because that would indicate that the patient’s symptoms are the result of a myasthenic crisis. A second dose of edrophonium would only worsen the symptoms. Pralidoxime is used to treat poisoning caused by irreversible cholinesterase inhibitors
