Материал: 2016_Kaplan_USMLE_Step_1_Lecture_Notes_Pharmacology

Chapter 9 λ CNS Drug List and Practice Questions

6.A patient comes to the ER with a painful stab wound. The ER resident administers pentazocine for the pain. Soon after administration the patient experiences sweating, restlessness, and an increase in pain sensations. What is the most likely explanation for his symptoms?

A.The patient is probably tolerant to pentazocine.

B.The patient is a heroin addict.

C.Pentazocine is an ineffective analgesic.

D.Pentazocine was used at the wrong dose.

E.Pentazocine doesn’t cross the blood-brain barrier.

7.The data shown in the table below concern the effects of drugs on transmitter function in the CNS. Which one of the drugs is most likely to alleviate extrapyramidal dysfunction caused by typical antipsychotics? (The + signs denote intensity of drug actions.)

8.Tricyclic antidepressants

A.have anticonvulsant activity

B.should not be used in patients with glaucoma

C.may increase oral absorption of levodopa

D.are sometimes used as antiarrhythmics

9.Which one of the following statements about lithium is accurate?

A.It causes symptoms of mild hyperthyroidism in up to 25% of patients.

B.Plasma levels are increased by a high-Na diet.

C.Adverse effects include acne, polydipsia, and polyuria.

D.Spina bifida is major concern in fetal development.

E.Sedative actions calm manic patients within 24 h.

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Section IV λ CNS Pharmacology

10.Ingestion of methanol in wood spirits would cause which of the following to happen?

A.The formation of formaldehyde

B.Nephrotoxicity

C.Hypotension and vomiting

D.The production of glycolic acids

E.Inhibition of aldehyde dehydrogenase

11.What Is the rationale for combining levodopa with carbidopa?

A.Carbidopa stimulates dopamine receptors

B.Carbidopa increases levodopa entry into the CNS by inhibiting peripheral dopa decarboxylase

C.Carbidopa enhances levodopa absorption

D.Carbidopa enhances the peripheral conversion of levodopa to dopamine

E.Carbidopa blocks peripheral COMT

12.A 29-year-old male patient is being treated with an antidepressant drug, and his mood is improving. However, he complains of feeling “jittery” and agitated at times, and if he takes his medication in the afternoon he finds it difficult to get to sleep at night. He seems to have lost weight during the 6 months that he has been taking the drug. He has been warned not to take other drugs without consultation because severe reactions have occurred with opioid analgesics including meperidine. This patient is probably taking

A.alprazolam

B.chlorpromazine

C.paroxetine

D.amitriptyline

E.trazodone

13.The ability of several drugs to inhibit the reuptake of CNS amine neurotransmitters is shown in the table below (number of arrows ↓ indicates the intensity of inhibitory actions). Which one of the drugs is most likely to have therapeutic effectiveness in the management of both obsessive-compulsive disorders (OCD) and major depressive disorders?

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Chapter 9 λ CNS Drug List and Practice Questions

14.A patient suffering from attention deficit hyperactivity disorder is placed on atomoxetine. A drug that has a similar mechansim of action to atomoxetine is

A.methylphenidate

B.botulinum toxin

C.clonidine

D.amitriptyline

E.entacapone

15.A patient suffering from generalized anxiety disorder (GAD) has a history of drug dependence that includes the illicit use of secobarbital (“reds”) and a variety of other drugs. Psychotherapy is indicated, but the physician also prescribes a drug that can be helpful in GAD and that has the advantage of no abuse liability. The drug prescribed was most likely to have been

A.bupropion

B.buspirone

C.baclofen

D.buprenorphine

E.phenobarbital

16.A patient has been diagnosed has having “long QT syndrome.” The patient is experiencing significant pain following a bout with shingles. What would be an appropriate drug for his pain?

A.Amitriptyline

B.Fentanyl

C.Acyclovir

D.Diazepam

E.Gabapentin

17.A habitual user of a schedule-controlled drug abruptly stops using it. Within 8 h, she becomes anxious, starts to sweat, and gets severe abdominal pain with diarrhea. These symptoms intensify over the next 12 h, during which time she has a runny nose, is lacrimating, and has uncontrollable yawning and intensification of muscle cramping and jerking. Assuming that these are withdrawal symptoms in the patient due to her physical dependence, the drug most likely to be involved is

A.alprazolam

B.amphetamine

C.ethanol

D.meperidine

E.secobarbital

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Section IV λ CNS Pharmacology

18.A 57-year-old patient, living at home, has severe pain due to a metastatic carcinoma that is being managed with fentanyl, delivered transdermally from a patch. He should also be taking, or at least have on hand

A.apomorphine

B.docusate

C.loperamide

D.morphine

E.naloxone

19.A hospital nurse is taking imipramine for a phobic anxiety disorder, and her patient is being treated with chlorpromazine for a psychotic disorder. Which of the following adverse effects is likely to occur in both of these individuals?

A.Excessive salivation

B.Pupillary constriction

C.Orthostatic hypotension

D.Seizure threshold

E.Weight loss

20.Which one of the following pairs of “drug/mechanism of action” is most accurate?

A.Carbamazepine/facilitation of the actions of GABA

B.Ethosuximide/blocks Na channels in axonal membranes

C.Phenelzine/inhibits dopa decarboxylase

D.Procaine/blocks Ca channels (type T) in thalamic neurons

E.Lithium/inhibits recycling of inositol

21.A 30-year-old male patient is brought to the ER with the following symptoms attributed to a drug overdose: HR and BP, mydriasis, behavioral excitation, aggressiveness, paranoia, and hallucinations. Of the following drugs, which one is most likely to be responsible for these symptoms?

A.Amphetamine

B.Ethanol

C.Fentanyl

D.Flunitrazepam

E.Marijuana

22.Which one of the following CNS receptors is directly coupled to an ion channel so that the effects of its activation do not involve second messenger systems?

A.N (ACh)

B.α (NE)

C.D2A (DA)

D.µ (beta endorphin)

E.5HT2 (serotonin)

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Chapter 9 λ CNS Drug List and Practice Questions

Answers

1.Answer: C. Most benzodiazepines are metabolized by liver cytochrome P450. In a patient lacking liver function, benzodiazepines that are metabolized via extrahepatic conjugation (e.g., lorazepam, oxazepam) are safer in terms of the possibility of excessive CNS depression. Lorazepam is metabolized, probably in the lungs, via glucuronidation. Although benzodiazepine actions can be reversed, the drug that acts as an antagonist is flumazenil, not naloxone.

2.Answer: E. Benzodiazepines interact with components of the GABA recep- tor–chloride ion channel macromolecular complex. Binding of BZs leads to an increase in the frequency of chloride ion channel opening elicited by the

inhibitory transmitter GABA. Benzodiazepines do not act on GABAB receptors; baclofen, a centrally acting muscle relaxant, is an agonist at these receptors. Buspirone, the selective anxiolytic, may be a partial agonist at 5HT receptors.

3.Answer: C. Morphine continues to be used in pulmonary congestion, in part because of its sedative (calming) and analgesic effects and also because of its vasodilating actions, which result in favorable hemodynamics in terms of cardiac and pulmonary function. Similarly, morphine is of value in an acute MI, especially its ability to relieve pain. However, morphine is not suitable for pain of biliary origin because it causes contraction of the sphincters of Oddi, leading to spasms. None of the other proposed indications are appropriate.

4.Answer: C. Benzodiazepines, barbiturates, and ethanol all modulate the actions

of the GABAA receptor, while baclofen works at the GABAB receptor, and dronabinol works on cannabinoid receptors. Of the GABAA drugs, only barbiturates have GABA-mimicking activity and this occurs at high doses. This is one of the reasons why barbiturates are a more dangerous group of drugs than benzodiazepines since benzos lack GABA-mimicking activity.

5.Answer: E. Phenytoin has the unusual characteristic of following first-order elimination kinetics at low doses but zero-order kinetics at high doses because of saturation of the liver enzymes involved in its metabolism. Carbamazepine, like most drugs, follows first-order kinetics. Both drugs are P450 inducers and can increase the metabolsim of oral contraceptives making them less effective. Both drugs are teratogenic, causing structural abnormalities during fetal development including cleft palate. Both drugs block inactivated sodium channels, preventing sodium entry, thereby prolonging the time to recovery.

6.Answer: B. Pentazocine is an agonist at κ (kappa) opioid receptors and an antagonist at µ opioid receptors. Mixed agonist-antagonists can displace µ receptor agonists such as heroin from receptors, resulting in the rapid development of symptoms of withdrawal in patients who are physically dependent on such drugs—“precipitated withdrawal.” Symptoms include yawning, lacrimation, salivation, restlessness, anxiety, sweating, goosebumps, muscle cramps, and pain.

7.Answer:C.Muscarinicreceptorantagonistssuchasbenztropine,trihexy-phenidyl, and diphenhydramine are used to manage the reversible extrapyramidal dysfunction (e.g., pseudo-Parkinsonism) that results from treatment with drugs that block DA receptors in the striatum (typical antipsychotics). Drugs that activate DA receptors, although theoretically possible, require doses that are toxic and exacerbate psychoses. Because the actions of DA in the striatum lead to inhibition of GABA-ergic neurons, drugs that activate GABA receptors are unlikely to be effective in this situation, although they may well have both anxiolytic and anticonvulsant properties.

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