Pharmacology 5

Question 1

A 3-year-old boy who aspirated a cherry pit is brought to the operating room for a rigid bronchoscopy. The anesthesiologist plans to do an inhalational induction with sevoflurane. Which of the following statements is the MOST accurate regarding the induction of this child compared to that of a healthy child?

Answer 1

Aspirating a foreign body can result in the obstruction of the right mainstem or a smaller bronchus. This leads to a portion of the lung that is not ventilated, but is perfused. Intrapulmonary shunt will result in a slower inhalational induction. The rise of FA/FI will be less steep (less rapid).

Question 2

Which of the following choices BEST explains why nalbuphine does not lead to increasing respiratory depression above 30 mg in adults?

Answer 2

Nalbuphine is a mu antagonist and kappa opioid receptor agonist which exhibits a plateau effect for respiratory depression.

Question 3

You want to administer rocuronium precurarization prior to succinylcholine in an attempt to prevent fasciculations. What is the appropriate dosage?

Answer 3

The recommended precurarization dosage for a nondepolarizing agent is 10% of the ED95, given about 3-5 minutes prior to succinylcholine. Using 10% of the intubating dose (20% of the ED95) is associated with an unacceptably high rate of side effects, including dyspnea in an awake patient.

Question 4

Use of sugammadex is MOST acceptable for a patient with which of the following characteristics?

Answer 4

Sugammadex is FDA approved for reversal of neuromuscular blockade by rocuronium or vecuronium in adult patients undergoing surgery. It is contraindicated in patients with known hypersensitivity to sugammadex or its components. Other patient populations or situations in which the use of sugammadex is not recommended and/or not FDA approved include: pediatric patients, patients with severe renal failure, reversal of NBDs other than rocuronium and vecuronium, and for reversal following rocuronium or vecuronium administration in ICUs.

TrueLearn Insight : Sugammadex is physically incompatible with ondansetron, ranitidine, and verapamil and should not be co-administered with these medications. If sugammadex and one of the above drugs are to be administered in the same line, the line should be adequately flushed with saline between administration of the two drugs.

Question 5

A 3-year-old male is brought to the emergency department with shortness of breath. Chest radiograph shows an object lodged in the right mainstem bronchus. The patient is taken to the operating room for removal of the foreign body. Which of the following is MOST accurate regarding induction of anesthesia in this patient compared to a healthy child?

Answer 5

Right to left shunt slows the speed of inhalational induction. This is more obvious in less soluble agents. In the presence of an intrapulmonary shunt, the speed of induction will affect (most to least): Nitrous Oxide > Desflurane > Sevoflurane > Isoflurane > Halothane.

TrueLearn Insight : Endobronchial intubation is another situation that produces a right to left intrapulmonary shunt.

Question 6

A 33-year-old female with a history of chronic opioid abuse is started on methadone. Which of the following is MOST TRUE regarding management during methadone treatment?

Answer 6

There is high individual patient variability in pharmacokinetics for methadone dosing. Patients on methadone therapy should have slow and careful titration of the drug during initiation of therapy, serial electrocardiograms, and routine urine drug screening. Dose adjustments are rarely needed for patients with renal disease.

TrueLearn Insight : Inhalational anesthetics and ondansetron can also cause QT prolongation. Treatment of Torsades de Pointes is intravenous magnesium.

Question 7

Which of the following is the MOST accurate statement regarding epidural administration of morphine and clonidine?

Answer 7

Clonidine is an effective analgesic drug. It has a longer epidural effect duration than morphine. When given in combination with morphine, the analgesic effect is enhanced.

Question 8

Which of the following statements is the MOST accurate regarding intravenous nicardipine usage?

Answer 8

Nicardipine is metabolized by the liver and eliminated via gastrointestinal tract. Renal insufficiency has no effect on nicardipine use. Severe hepatic insufficiency results in significantly prolonged nicardipine half-life.
Nicardipine (intravenous and oral) can cause an increase in heart rate in about 25% of the people. This tachycardia is NOT due to baroreceptor response, rather due to sympathetic activation. Nicardipine decreases systemic vascular resistance, but also increases cardiac contractility

Question 9

Which of the following drugs must be metabolized to exert its clinical effects?

Answer 9

Codeine is an opiate prodrug whose effects are primarily dependent on metabolism to morphine, which requires the cytochrome P450 enzyme CYP2D6.

TrueLearn Insight : To remember which CYP is most involved with codeine: “coDeine” has 2 letters then D and 6 letters total aside from the D (2D6).

Question 10

Which of the following will affect the onset of analgesia from local anesthetics the LEAST?

Answer 10

The onset of effect of a local anesthetic is affected by its concentration (higher is faster), lipid solubility (higher is faster), pKa (lower is faster), and environment pH (higher is faster). Anything that increases the concentration or proportion of local anesthetic in its unionized form will speed the onset of analgesia.

Question 11

Which of the following is LEAST likely to be associated with QT prolongation?

Answer 11

Aprepitant is a neurokinin type 1 (NK1) receptor antagonist and has shown good efficacy for the prevention of vomiting for up to 48 hours postoperatively. Aprepitant has not been shown to cause any changes in ECG, whereas several other antinausea medications such as droperidol, haloperidol, and ondansetron can cause QT prolongation.

Question 12

For which of the following operations is the use of nitrous oxide MOST appropriate?

Answer 12

Nitrous oxide should be avoided in situations where bowel distention could be particularly hazardous. Both the length of time administered and the concentration of nitrous oxide lead to increasing bowel distention.

TrueLearn Insight : An air-filled endotracheal tube cuff is susceptible to expansion by nitrous oxide. At 75% nitrous oxide a cuff can double or triple in volume causing pressure on the tracheal mucosa. Similarly, nitrous oxide may expand the cuffs of balloon-tipped (e.g. pulmonary artery) catheters. The air expansion is rapid and a doubling of catheter volume may occur within 10 minutes.

Question 13

Which of the following is a gastrointestinal side effect of glycopyrrolate?

Answer 13

Glycopyrrolate delays gastric emptying, decreases salivary and gastric secretions, increases heart rate, relaxes bronchial smooth muscle, decreases lower esophageal sphincter tone, and causes urinary retention.

Question 14

Which of the following is the site of action for tirofiban?

Answer 14

Abciximab, eptifibatide, and tirofiban are GP IIb-IIIa receptor inhibitors that prevent platelet aggregation and thrombus formation.

Question 15

Metoclopramide is contraindicated in which of the following patients?

Answer 15

Metoclopramide is a promotility antiemetic contraindicated in patients with complete bowel obstruction. Combinations involving metoclopramide are not found to reduce PONV to a greater extent than monotherapy. Metoclopramide is a weak antiemetic and at a dose of 10 mg is not effective in reducing the incidence of nausea and vomiting.

TrueLearn Insight : Metoclopramide inhibits plasma cholinesterase and can increase the duration of action of succinylcholine.

Question 16

Which of the following statements regarding the cardiovascular and respiratory effects of morphine is FALSE?

Answer 16

Morphine reduces preload and afterload. This reduces myocardial oxygen demand and improves coronary perfusion pressures by reducing ventricular EDV and EDP. Morphine has minimal effect on myocardial contractility by itself but may cause myocardial depression when combined with volatile anesthetics. All µ-opioid agonists cause dose-dependent respiratory depression by decreasing the sensitivity of central chemoreceptors to elevated levels of CO2.

TrueLearn Insight : Evoked Potential: Morphine and its active metabolites, morphine-6-glucuronide and morphine-3-glucuronide, are excreted via the kidneys. Morphine-6-glucuronide is a more potent and a longer-lasting opioid agonist than morphine itself. This makes morphine relatively contraindicated in renal failure.

Question 17

A 64-year-old woman with a history of essential tremor is chronically treated with primidone. She underwent implantation of a deep brain stimulator which was complicated by intracranial hemorrhage. She is intubated and transferred to the ICU. You are considering a midazolam infusion for sedation. Which of the following mechanisms is MOST likely to cause an increased dose requirement of midazolam in this patient?

Answer 17

Chronic administration of barbiturates decreases the duration of action of drugs metabolized by cytochrome p450, such as midazolam

Question 18

A 56-year-old man with a history of end-stage renal disease undergoes a Whipple procedure for cholangiocarcinoma during which cisatracurium is used for neuromuscular blockade. Which of the following combinations of patient pH and temperature would result in an increased metabolism of cisatracurium?

Answer 18

Cisatracurium undergoes nonenzymatic Hofmann elimination in plasma. The reaction speed is increased with higher pH and higher temperature. As the drug undergoes minimal renal or hepatic metabolism, it is safe to use in patients with significant kidney or liver disease.

Question 19

Excessive intraoperative fluid administration is BEST avoided in patients receiving which of the following antineoplastic agents?

Answer 19

Several antineoplastic drugs, including doxorubicin, cyclophosphamide, 5-fluorouracil, paclitaxel, and rituximab, are capable of causing cardiac toxicity with resultant heart failure. As with any patient with cardiomyopathy, careful attention must be paid to fluid administration to avoid the complications associated with heart failure, such as pulmonary edema.

Question 20

Which of the following is a mechanism by which dopamine acts?

Answer 20

Dopamine is a naturally occurring catecholamine that stimulates beta-1 and alpha-1 adrenergic receptors as well as D-1 dopamine receptors, which are primarily located in the renal and mesenteric vasculature. The response to exogenously administered dopamine depends on the dose given. At lower concentrations, dopamine primarily acts on the D-1 dopamine receptors to produce vasodilation of the renal, mesenteric, and coronary vasculature. The main result is an increase in the glomerular filtration rate and renal blood flow. Furthermore, low dose dopamine will result in sodium excretion which will increase urine output.

Higher doses will stimulate the beta-1 receptors to increase release of norepinephrine from sympathetic nerve terminals. The end result is an increase in heart rate, systolic blood pressure, and pulse pressure. At the highest doses, dopamine administration will stimulate alpha-1 receptors which results in peripheral vasoconstriction.

Question 21

How is 2-chloroprocaine metabolized?

Answer 21

2-chloroprocaine is an ester local anesthetic that is metabolized rapidly by plasma cholinesterase.

Question 22

What is the most common cause of hypoxemia in a patient using an IV PCA with opioids?

Answer 22

Hypoventilation is the primary cause of hypoxemia in patients receiving opioids.

Question 23

Minimum alveolar concentration requirements for volatile agents are reduced by which of the following?

Answer 23

Factors that decrease MAC are those that decrease neurotransmission, decrease CNS neurotransmitter levels, or decrease cerebral metabolism including hyponatremia.

TrueLearn Insight : Magnesium administration has a curious effect on anesthetic requirements. Studies have shown that it decreases anesthetic requirements during TIVA. However, the opposite has been shown with volatile anesthetics where it increases MAC. To further confuse the picture, rats who were fed a low magnesium diet (hypomagnesemic) had higher MAC requirements.

Question 24

What is the expected initial hemodynamic effect after giving dexmedetomidine as a bolus dose of 2 mcg/kg?

Answer 24

A bolus dose of dexmedetomidine has a biphasic hemodynamic response. Initially, dexmedetomidine stimulates peripheral alpha-2 receptors resulting in hypertension and subsequent decrease in heart rate and cardiac output. The peak hypertensive response occurs around three minutes after the bolus dose is given and the blood pressure returns to baseline after around ten minutes. Subsequently, there is a slow decline in blood pressure over the next hour.

Question 25

Via which of the following mechanisms does etomidate cause adrenal suppression?

Answer 25

Etomidate inhibits adrenal steroidogenesis by inhibiting the enzyme 11-β hydroxylase which is responsible for cortisol and aldosterone production. Adrenal suppression is most pronounced with long-term use, but can also occur transiently after a single dose.

Question 26

In patients with which of the following conditions would an angiotensin converting enzyme (ACE) inhibitor be contraindicated?

Answer 26

ACE-I are contraindicated in pregnancy, history of angioedema, and allergy to ACE-I. Relative contraindications include hypotension and hyperkalemia. There is controversy over the perioperative risks and benefits of withholding ACE-I on the day of surgery; however, ACE-I use on the day of surgery is associated with increased intraoperative hypotension.

Question 27

Aspirin irreversibly inhibits platelet aggregation by inhibiting the formation of which of the following?

Answer 27

Aspirin irreversibly inhibits COX thereby preventing the synthesis of Thromboxane-A2.

Question 28

A 32-year-old obese female with bipolar disorder and hypertension is undergoing an elective gastric banding procedure. She takes simvastatin, lisinopril, and lithium. Which of the following statements about lithium is TRUE?

Answer 28

Lithium prolongs action of both depolarizing and nondepolarizing neuromuscular blockers.

TrueLearn Insight : Lithium may decrease anesthetic requirements (lower MAC) because it blocks brainstem release of norepinephrine, epinephrine, and dopamine.

Question 29

The following ECG tracing is most likely to be found in a patient taking which of the following medications?
Tall T waves

Answer 29

Amiloride, triamterene, spironolactone, and eplerenone are the four potassium sparing diuretics. They work by blocking sodium reabsorption in the cortical collecting tubule and simultaneously increasing potassium reabsorption.

Question 30

Which of the following medications causes the LEAST reduction in minimum alveolar concentration of volatile anesthetics?

Answer 30

Most opioids significantly lower volatile anesthetic MAC requirements when administered concurrently. However, partial opioid agonists and mixed agonist-antagonists have a greatly reduced, and nearly clinically insignificant, effect on MAC.

Question 31

A patient in the post-anesthesia care unit after eye surgery has significant nausea and vomiting. In the operating room, the patient received dexamethasone and ondansetron for nausea prophylaxis. Which of the following medications is NOT recommended?

Answer 31

In patients who received ondansetron intraoperatively, metoclopramide as well as ondansetron are not recommended for rescue therapy. Use of a medication from a different class is most effective.

Question 32

A 46-year-old male with a history of cirrhosis secondary to alcoholism presents for colectomy. He weighs 60 kg with a BMI of 19 kg/m2. General anesthesia is induced and a muscle relaxant is used for paralysis. Which of the following is TRUE in regards to neuromuscular blocking agents in this patient?

Answer 32

Intubating doses of neuromuscular blocking drugs are increased in cirrhosis because of the increase in volume of distribution. Maintenance doses of hepatically metabolized and/or cleared drugs should be reduced and neuromuscular function carefully monitored as duration of action is prolonged.

Question 33

Which of the following opioids, when administered alone, is MOST likely to cause tachycardia at high doses?

Answer 33

Opioids are routinely used to prevent tachycardia and reduce myocardial oxygen demand. However, high doses of meperidine can cause tachycardia due to its atropine-like effects.

Question 34

A 45-year-old male with chronic pain is scheduled for a three-hour long abdominal procedure. Which of the following is MOST likely to occur perioperatively if this patient took oral clonidine before surgery?

Answer 34

Clonidine decreases anesthetic requirements (decreased MAC), is a useful co-analgesic particularly in chronic pain patients, reduces post-operative shivering, and reduces post-operative nausea.

Question 35

Which of the following is MOST commonly seen with the use of ketorolac?

Answer 35

Ketorolac can decrease GFR, especially when administered for greater than 5 days, via inhibition of afferent renal artery vasodilation.

Question 36

What is the principal pathway of biotransformation for lorazepam?

Answer 36

Lorazepam undergoes glucuronidation metabolism in the liver without any phase I metabolism.

Question 37

A 65-year-old diabetic female is admitted to the ICU for septic shock from an infected decubitus ulcer. Her vitals are as follows:

HR: 110 beats per minute
BP: 80/40 mm Hg
CVP: 2 mm Hg
SpO2: 98% on 50% FiO2
Temperature: 38.7 degrees Celsius
Urine output: 0.25 mL/kg/hr

Transthoracic echocardiography using the subxiphoid view shows > 50% collapse of the IVC with inspiration. Broad spectrum antibiotics are administered and the patient is started on a norepinephrine infusion. Which of the following changes is MOST likely to occur with the use of norepinephrine in this setting?

Answer 37

Norepinephrine can worsen splanchnic and renal blood flow secondary to alpha1 mediated vasoconstriction. Heart rate and cardiac output decrease due to baroreceptor reflexes and increased afterload while cardiac work increases.

Question 38

Which of the following medications should be AVOIDED in a patient taking selegiline?

Answer 38

Meperidine is a weak serotonin reuptake inhibitor and can therefore lead to serotonin syndrome if given to patients taking MAO inhibitors.

TrueLearn Insight : Indirect sympathomimetics, such as ephedrine, can produce exaggerated response in patients taking MAOIs as they trigger the release of accumulated catecholamines.

Question 39

A 20-year-old male presents for repair of a tibial fracture. He has a history of rash after penicillin exposure when he was a child and did not require treatment at that time. The orthopedic surgery team requested cefazolin for antibiotic prophylaxis prior to knowing about this reaction to penicillin. Which of the following is MOST appropriate for this patient?

Answer 39

Studies have shown that patients who report penicillin allergy and do not have a history of severe reactions (whether IgE-mediated or non-IgE-mediated) can safely receive cephalosporin antibiotics.

Question 40

Which of the following drugs is metabolized via ester hydrolysis?

Answer 40

Remifentanil is the only opioid hydrolyzed in the serum by plasma esterases; all other opioids are metabolized by the liver.