Pharmacology 1

Question 1

A 44-year-old, 5’2”, 120 kg (50 kg ideal body weight) female is undergoing laparoscopic Roux-en-Y gastric bypass for morbid obesity. During the surgery, she received a total of 110 mg of rocuronium. At the end of surgery, she has two twitches in response to train-of-four stimulation at the adductor pollicis muscle. Which of the following is the MOST appropriate dose of sugammadex to administer to reverse her neuromuscular blockade at this time?

Answer 1

There are three recommended doses for sugammadex in adults based on the clinical indication and the degree of NMB.

2mg/kg - 2 twitches
4mg/kg - no twitches
16mg/kg - Use of a 16 mg/kg dose of sugammadex following rapid sequence intubation with rocuronium cannot be relied upon as a rescue solution for an unanticipated cannot intubate, cannot ventilate scenario. The management of a cannot intubate/ventilate scenario should primarily focus on facilitating airway patency, oxygenation, and ventilation per the American Society of Anesthesiologists’ difficult airway algorithm.

Question 2

High-dose phenylephrine will MOST likely cause which of the following changes in splanchnic blood perfusion?

Answer 2

a1 receptor activation from high dose phenylephrine leads to decreased splanchnic perfusion from arterial and venous constriction.

Question 3

Extravasation of which of the following drugs is LEAST likely to cause local tissue injury?

Answer 3

Diazepam, phenytoin, promethazine, and thiopental are vesicants. Extravasation of each of these medications has been associated with severe local tissue necrosis, gangrene, or amputation.

Question 4

Which of the following is NOT a mechanism by which nitroprusside toxicity occurs?

Answer 4

Nitroprusside is metabolized to cyanide ions and toxicity can occur following lengthy infusions. The three major mechanisms for nitroprusside toxicity are

1) Cyanide ions bind to cytochrome c oxidase and inhibit cellular aerobic respiration.
2) Formation of cyanmethemoglobin which is unable to carry oxygen.
3) Thiocyanate production which causes CNS-related effects.

Question 5

The following ECG finding is LEAST likely after administration of which of the following medications?
Tall peaked T waves

Answer 5

ACEIs/ARBs, aldosterone antagonists, and succinylcholine administration may lead to hyperkalemia.

TrueLearn Insight : Enalapril is one of many drugs that have been implicated in drug-induced lupus.

Question 6

A patient you are evaluating for complex neurosurgery is taking aspirin for a history of coronary artery disease. If the patient stopped the aspirin today, what percentage of platelets would be restored in 24 hours?

Answer 6

For each day after interruption of any agent which irreversibly inhibits platelet function (aspirin, clopidogrel), approximately 10% to 14% of normal platelet function is restored. Therefore it can take 7 to 10 days for an entire platelet pool to be replenished.
Antiplatelet Agents:
Aspirin Inhibits thromboxane A2 synthesis
Clopidogrel (Plavix)
Prasugrel (Effient)
Ticagrelor (Brilinta) Inhibit ADP receptor activation
Dipyridamole (Persantine)
Cilostazol (Pletal) Lowers calcium by elevating cAMP
Abciximab (ReoPro)
Tirofiban (Aggrastat)
Eptifibatide (Integrilin) Blocks GP IIb/IIIa receptors
Anticoagulation Agents:
Warfarin (Coumadin) Inhibit vitamin K dependent coagulation factors (II, VII, IX, X)
Unfractionated heparin Antithrombin mediated inhibition of serine proteinases
Low molecular weight heparin Antithrombin mediated inhibition of serine proteinases
Fondaparinux (Arixtra) Antithrombin mediated inhibition of factor Xa
Dabigatran (Pradaxa) Direct thrombin inhibition
Rivaroxaban (Xarelto) Direct factor Xa inhibition
Apixaban (Eliquis) Direct factor Xa inhibition

Question 7

When used at sedation doses, which of the following adverse effects is MORE common with fospropofol compared to propofol?

Answer 7

The most common side effects of the water-soluble propofol prodrug fospropofol are paresthesias (typically perianal or genital) and genital pruritus. Due to its slower onset of action, the incidence of respiratory depression, apnea, and hypotension are lower with fospropofol compared to propofol.

Question 8

The effects of mannitol MOST closely resemble the effects of which of the following conditions?

Answer 8

Hyperglycemia can mimic the effects of mannitol by acting as an osmotic diuretic.

TrueLearn Insight : Mannitol is relatively contraindicated in patients with congestive heart failure (CHF) due to an initial increase in intravascular volume. Furosemide is the drug of choice when diuresis is recommended in this class of patients.

Question 9

Which of the following explains why the rate of rise of FA/FI for nitrous oxide is faster than that for desflurane?

Answer 9

Solubility of commonly used anesthetics is: desflurane > nitrous oxide > sevoflurane > isoflurane from least soluble to most soluble.
The concentration effect occurs when a high concentration of anesthetic can be used. Currently the only anesthetic in clinical use in which the concentration effect can be demonstrated is nitrous oxide. This effect explains why nitrous oxide has a more rapid onset than desflurane.

Question 10

A patient on high dose beta blockade is scheduled for coronary artery bypass grafting. Following cardiopulmonary bypass, the patient’s cardiac output is severely low despite aggressive pharmacological management. Which of the following BEST explains why a glucagon infusion should be started?

Answer 10

Glucagon increases intracellular cAMP which results in increased inotropy and chronotropy in cardiac myocytes. This effect is mediated through a specific, nonadrenergic receptor.
Glucagon is generally not considered a first line therapy for low cardiac output (CO) states, but may be beneficial in the following situations after conventional therapies have failed: (1) low CO following cardiopulmonary bypass (CPB), (2) low CO following myocardial infarction, (3) chronic congestive heart failure, (4) low CO from excess β-blockade, and (5) anaphylactic shock with refractory hypotension.

Question 11

Which of the following is the major reason why infants have an increased volatile anesthetic uptake compared to an adult?

Answer 11

Infants have a higher initial uptake of volatile anesthetic than adults due to their minute ventilation to FRC ratio.

Infants have a lower FRC compared with adults which provides less “air” to dilute the volatile anesthetic being breathed. However, the infant’s higher minute ventilation places more volatile anesthetic in the alveoli where it can be taken up. This increased minute ventilation is the reason why infants have a higher uptake and faster induction with volatile anesthetics compared to adults.

Question 12

A rapid sequence induction and intubation is planned and the patient is given a small dose of nondepolarizing neuromuscular blocker. After this, an induction agent and succinylcholine are administered. Of the following, which is the MOST likely to be seen in this patient?

Answer 12

he occurrence of succinylcholine-induced fasciculations and increases in ICP and intragastric pressure may be decreased by NDNB pretreatment. Increases in IOP will occur despite pretreatment and current recommendations are to avoid succinylcholine in open-eye injuries.

Question 13

A rapid sequence induction and intubation is planned and the patient is given a small dose of nondepolarizing neuromuscular blocker. After this, an induction agent and succinylcholine are administered. Of the following, which is the MOST likely to be seen in this patient?

Answer 13

The occurrence of succinylcholine-induced fasciculations and increases in ICP and intragastric pressure may be decreased by NDNB pretreatment. Increases in IOP will occur despite pretreatment and current recommendations are to avoid succinylcholine in open-eye injuries.

Question 14

An elderly patient is inadvertently given twice the expected dose of midazolam and fentanyl prior to a nerve block procedure. She becomes unconscious and flumazenil is administered. Which of the following is MOST likely to be seen?

Answer 14

Due to the short half-life of flumazenil, recrudescence of benzodiazepine-induced somnolence is common after its use.

Question 15

Which of the following is associated with ketamine?

Answer 15

Ketamine is unique when compared to many other intravenous anesthetics: airway reflexes and respiratory drive are relatively preserved, significant analgesia is produced, and sympathetic tone is increased. Ketamine’s analgesic effect is present even with relatively small doses

Question 16

Which of the following is MOST likely observed on ECG after multiple blood transfusions in a patient with severe liver dysfunction?

Answer 16

Patients with liver dysfunction who receive multiple blood transfusions can develop hypocalcemia due to calcium chelation by citrate. Hypocalcemia manifests as a prolonged QT interval on ECG due to its effects on the 2 types of cardiac action potentials. Less sarcoplasmic calcium is available for the calcium-activated potassium current during repolarization (phase 3) of the ventricular (nonautomatic) muscle fibers. This slows the repolarization and prolongs the return of the action potential to the resting phase (phase 4). Hypocalcemia results in slowed depolarization within the nodal fibers (automatic) by lengthening phase 0 and delaying action potential transmission.

Question 17

Which of the following statements about the physiologic effects of isoflurane is MOST accurate at a minimum alveolar concentration of 1.0?

Answer 17

At 1.0 MAC of isoflurane, cardiovascular effects include increased heart rate (10-15 beats/min), decreased SVR and blood pressure, and minimal changes in CVP. Respiratory effects include a mild reduction in minute ventilation, a reduced tidal volume, and an increased respiratory rate.

Question 18

Which of the following blood chemistry derangements is LEAST likely in a patient taking hydrochlorothiazide?

Answer 18

Hydrochlorothiazide can cause hypokalemia, hypomagnesemia, hyponatremia, hypercalcemia, hyperuricemia, hyperglycemia, hypercholesterolemia, increased LDL production, and hypertriglyceridemia.

Question 19

A young male, undergoing open reduction internal fixation of a pelvic fracture and external fixation of a tibial plateau fracture following a motorcycle accident, develops elevated creatinine phosphokinase (CPK) and altered renal function. The patient is an otherwise healthy professional body builder who weighs 135 kg. The surgical time is going on eight hours and the patient has been hemodynamically stable. Which of the following is MOST likely the cause of this finding?

Answer 19

Rhabdomyolysis can occur following a multitude of clinical pictures. In the operative period, it can occur following malignant hyperthermia, prolonged tourniquet application, compartment syndrome and prolonged operative times in larger patients.

Question 20

Dosing an epidural for cesarean section with morphine will MOST likely INCREASE which of the following compared to an epidural dosed with fentanyl?

Answer 20

Use of epidural lipophilic opioids (e.g. fentanyl) is associated with a decreased risk of nausea and vomiting and possibly pruritus compared to epidural use of more hydrophilic opioids (e.g. morphine).

TrueLearn Insight : The ASA recommends a longer period of monitoring for respiratory depression following a single neuraxial dose of morphine compared to fentanyl. For lipophilic opioids: continual monitoring for at least 20 minutes following administration and then at least hourly monitoring for the next two hours. For hydrophilic opioids: at least hourly monitoring for the first 12 hours and then monitoring at least every two hours for the next 12 hours.

Question 21

Following an induction dose of thiopental, which of the following MOST significantly contributes to the drug’s termination of action?

Answer 21

The termination of action of the effects of a bolus dose of thiopental is primarily due to redistribution of the drug from the brain to peripheral tissues rather than by metabolism. The same is seen with bolus doses of methohexital, propofol, and fentanyl.

Question 22

Which of the following lists the order of volatile anesthetic metabolism, from greatest to least?

Answer 22

Sevoflurane undergoes the most extensive metabolism (5-8%) followed by isoflurane (0.2%) then desflurane (< 0.2%).

Question 23

Which of the following statements about patients with pseudocholinesterase deficiency is TRUE?

Answer 23

Pseudocholinesterase deficiency prolongs the actions of succinylcholine and mivacurium which can lead to prolonged neuromuscular blockade and apnea.

TrueLearn Insight : Echothiophate is an anticholinesterase used to treat refractory glaucoma by causing miosis. Since it inhibits BCHE, systemic absorption can cause up to a 95% decrease in BCHE function, thereby potentiating the effects of succinylcholine.
A and K variants are most common

Question 24

A 34-year-old obese male becomes moderately hypotensive during an elective hernia repair but his only IV is infiltrated. An intramuscular (IM) injection is considered. Which of the following medications should NOT be administered intramuscularly to improve his blood pressure?

Answer 24

Phenylephrine is a direct-acting α1 agonist. It improves blood pressure via increased preload and afterload but typically causes a reflexive bradycardia. Although phenylephrine mimics many of the effects of norepinephrine, it is less potent and causes venoconstriction > arterial constriction and is accordingly safe for IM administration. An IM dose of 2-5 mg will raise blood pressure and lower heart rate typically within 10-15 minutes from injection.

Bottom Line: Cardiovascular medications that can be given intramuscularly include, but are not limited to atropine, glycopyrrolate, ephedrine, epinephrine, phenylephrine, and hydralazine.

Question 25

Which of the following neuromuscular blocking drugs has the LEAST increase in dosage requirements for burn patients?

Answer 25

Mivacurium, due to its degradation by pseudocholinesterase (levels of which are decreased in burn patients), requires the smallest increase in dosage for burn patients.
Patients with massive burns demonstrate resistance to NDNMBs, resulting in increased dosing requirements, due to upregulation of ACh receptors and increased plasma protein binding. Mivacurium’s dosing requirements are only slightly increased relative to other NDNMBs as it is metabolized by pseudocholinesterase, the levels of which are decreased in burn patients.

Question 26

Which of the following drugs can reduce the incidence of emergence delirium associated with the use of ketamine?

Answer 26

Benzodiazepines, propofol, and barbiturates can decrease ketamine-induced emergence delirium.

Question 27

Which of the following is NOT an immediate side effect from intravenous amiodarone?

Answer 27

Intravenous amiodarone can cause hypotension, cardiac effects, acute respiratory distress syndrome, nausea, vomiting, abnormal liver function tests, and phlebitis when given through a peripheral intravenous line. The cardiac side effects include bradycardia, asystole, heart failure, and shock.
Chronic therapy affects PFTs, LFTs, and TFTs (pulmonary, liver, thyroid) and can also cause a blue/grey skin discoloration.

Question 28

Match the following enzyme or receptor polymorphisms that are associated with altered pharmacokinetics of each drug. Answer choices may be used once, more than once, or not at all.
Morphine

Answer 28

a polymorphism in the OPRM gene may render morphine less effective in some patients, while polymorphisms in the melanocortin 1 receptor (MC1R) gene, which is also associated with red hair, may lead to increased analgesia.

Question 29

Match the following enzyme or receptor polymorphisms that are associated with altered pharmacokinetics of each drug. Answer choices may be used once, more than once, or not at all.
Omeprazole

Answer 29

The cytochrome P450 enzymes display various polymorphisms that lead to altered drug metabolism. Cytochrome P450 2C19 (CYP2C19) is responsible for the metabolism of proton pump inhibitors, such as omeprazole, and antidepressants which may lead to therapeutic success or failure of these medications depending on if the enzyme is hyperactive or underactive

Question 30

Match the following enzyme or receptor polymorphisms that are associated with altered pharmacokinetics of each drug. Answer choices may be used once, more than once, or not at all.
Tramadol

Answer 30

Cytochrome P450 2D6 (CYP2D6) is a particularly important P450 enzyme to anesthesiologists as it metabolizes many medications we administer such as codeine, beta-blockers, some antiarrhythmics, diltiazem, and tramadol (C). These medications rely on CYP2D6 for creation of active metabolite

Question 31

Match the following enzyme or receptor polymorphisms that are associated with altered pharmacokinetics of each drug. Answer choices may be used once, more than once, or not at all.
Warfarin

Answer 31

Cytochrome P450 2C9 (CYP2C9) metabolizes phenytoin, warfarin, and ibuprofen (B). Poor warfarin metabolizes can have excessive anticoagulation.