Pharmacology

Question 1

Which step of the pain pathway can be described as the following: the pain signal is either inhibited or augmented as it advances towards the cerebral cortex
a. transduction
b. modulation
c. transmission
d. perception

Answer 1

b. modulation

The most important site of modulation is in the substantia gelatinosa (in the dorsal horn Rexed laminae II and III)

Question 2

Which of the following drugs affect how we “feel” about pain?
a. NMDA antagonists
b. opioids
c. SSRIs
d. NSAIDS

Answer 2

b. opioids

Perception is the processing of pain signals and cerebral cortex and limbic system. Drugs that target perception include: opioids, general anesthetics, alpha 2 agonists

Question 3

Which part of the pain pathway do local anesthetics work on? Select 2
a. modulation
b. transmission
c. transduction
d. perception

Answer 3

b&c

Local anesthetics target both transmission and transduction. Transduction is when a chemical, mechanical or thermal stimulus is sensed and converted into an action potential. Transmission is when the pain signal is transmitted from the periphery to the central nervous system along the 3 neuron pathway via the spinothalamic tract.

Question 4

Which of the following opioid receptors is associated with bradycardia?
a. kappa
b. mu
c. delta
c. theta

Answer 4

b. mu

Mu receptors are associated with most of the classical symptoms related to opioid administration. Delta and Kappa are not associated with heart rate changes such as bradycardia.

Question 5

Which opioid receptor is NOT associated with urinary retention?
a. beta
b. delta
c. kappa
d. mu

Answer 5

c. kappa

Kappa receptors are associated with diuresis unlike delta and mu which are associated with urinary retention.

Question 6

Which opioid receptor plays an important role in anti shivering?
a. beta
b. mu
c. kappa
d. delta

Answer 6

c. Kappa

Question 7

Which mu receptor subtype is associated with the respiratory depression seen with opioid administration
a. mu 1
b. mu 2
c. mu 3
d. mu 4

Answer 7

b. Mu 2

There are three mu receptor subtypes (1,2 &3). Subtype 2 is associated with respiratory depression along with constipation, bradycardia and physical dependence (also spinal analgesia).

Question 8

Which mu receptor subtype is responsible for the euphoric feeling that a patient may have?
a. mu 1
b. mu 2
c. mu 3
d. mu 4

Answer 8

a. mu 1

Mu 1 is responsible for euphoria, bradycardia, miosis, hypothermia, urinary retention and a low potential of abuse.

Question 9

Which part of the brain do opioids stimulate to induce nausea and vomiting?
a. Chemoreceptor trigger zone
b. Edinger Westphal nucleus
c. Locus coeruleus
d. Rostral central medulla

Answer 9

a. Chemoreceptor trigger zone

Chemoreceptor trigger zone in the area postrema (medulla) is what is stimulated to produce n/v. Possible stimulation of the vestibular apparatus is involved as well.

Question 10

Decreased BP with administration of morphine and meperidine is mostly a result of what?
a. bradykinin
b. histamine
c. vasodilation
d. decreased myocardial contractility

Answer 10

b. histamine

Histamine release from morphine and meperidine can decrease BP. In fact, opioids have minimal impacts on BP in healthy patients. There is dose dependent vasodilation. Baroreceptor reflex is not affected.

Question 11

When given with opioids, what medication can cause myocardial depression
a. esmolol
b. nicardipine
c. N20
d. morphine

Answer 11

c. N20

When given with opioids, N20 can cause myocardial depression. Opioids alone do not affect myocardial contractility.

Question 12

Opioids are responsible for all the following systemic effects accept for …
a. Detrusor muscle relaxation
b. relaxation of the sphincter of Oddi
c. prolonged gastric emptying
d. decreased core body temperature

Answer 12

b. relaxation of sphincter of Oddi

Opioids actually cause contraction of the sphincter of Oddi which can lead to increased biliary pressures. This can be reversed by giving naloxone or glucagon. Meperidine causes the lowest increase in biliary pressure among the opioids.

Question 13

In women, morphine is associated with all the following except…
a. shorter duration of action
b. lower post operative opioid consumption
c. greater analgesic potency
d. slower onset of action

Answer 13

a. shorter duration of action

Gender plays a role in the PK/PD differences among genders. In women, morphine has a longer duration of action compared to men.

Question 14

Which opioid is the standard by which all other opioids are compared?
a. fentanyl
b. meperidine
c. hydromorphone
d. morphine

Answer 14

d. morphine

Morphine 10mg IV is the standard which all other opioids are compared to.

Question 15

Which term describes the following: when a patient requires higher doses of a drug to achieve a given effect
a. addiction
b. dependence
c. tolerance
d. withdrawal

Answer 15

c. tolerance

Tolerance develops to nearly all the side effects of opioids except constipation and miosis.

Question 16

Which opioid is the most potent?
a. sufentanil
b. remifentanil
c. hydromorphone
d. alfentanil

Answer 16

a. sufentanil

The following is the order of opioids from most to least potent

sufentanil>fentanyl=remifentanil>alfentanil>hydromorphone>morphine>meperidine

Question 17

All of the following opioids are classified as synthetic opioids except…
a. meperidine
b. fentanyl
c. methadone
d. morphine

Answer 17

d. morphine

Morphine is a naturally occurring opioid - a phenanthrene derivative. Codeine is a prodrug that produces morphine

Question 18

Morphine withdrawal has a duration of…
a. 6-7 weeks
b. 4-5 days
c. 7-10 days
d. 1-2 days

Answer 18

c. 7-10 days

Morphine and heroin have an onset of 6-18h, a peak of 36-72h and a duration of 7-10 days. Methadone has a duration of 6-7 weeks and fentanyl/meperidine have a duration of 4-5 days

Question 19

Which opioid does not undergo hepatic biotransformation?
a. morphine
b. fentanyl
c. remifentanil
d. hydromorphone

Answer 19

c. remifentanil

Remifentanil is hydrolyzed in the plasma by tissue esterases. It is not metabolized by pseudocholinesterase and is not affected by a deficiency. Remifentanil is lipophilic by it behaves like a drug with a low Vd because it is metabolized so quickly in the plasma. This is why remifentanil is dosed by LBW

Question 20

Which opioid is structurally related to atropine and can cause tachycardia, dry moth and mydriasis?
a. fentanyl
b. morphine
c. sufentanil
d. meperidine

Answer 20

d. meperidine

Meperidine is constructed from an atropine like ring and can cause anticholinergic side effects

Question 21

Which opioid, when administered with MAOs can cause serotonin syndrome?
a. morphine
b. hydrocodone
c. fentanyl
c. meperidine

Answer 21

c. meperidine

Meperidine is a weak serotonin reuptake inhibitor. S/Sx are changes in mental status, hyperreflexia, hyperthermia, seizures and death

Question 22

Stimulation of what receptor is responsible for the anti shivering effects of meperidine?
a. kappa
b. mu
d. delta
c. beta

Answer 22

a. kappa

Stimulation of the kappa receptor decreases shivering and therefore decreases oxygen consumption in the shivering patient

Question 23

Which of the following opioids does NOT cause histamine release?
a. morphine
c. codeine
d. hydrocodone
c.mereidine

Answer 23

d. hydrocodone

The other opioids cause histamine release from mast cells

Question 24

The active metabolite of meperidine (normeperidine) has the following potency related to the parent compound?
a. 2x the potency
b. inactive metabolite (no potency)
c. 1/2 potency
d. 8x potency

Answer 24

c. 1/2 potency

Meperidine is demethylated by CYP450. The elimination time is 15 hours can be be as much as 35 hours in the patient with renal failure. Normeperidine can cause myoclonus, reduces the seizure threshold and cause CNS excitability. Meperidine should be avoided in patients with renal failure and the elderly.

Question 25

Which of the following opioids has the lowest pKA?
a. morphine
b. remifentanil
c. alfentanil
d. meperidine

Answer 25

c. alfentanil

The pKA of alfentanil is 6.5. It is a weak base unlike the other opioids that have a pKA greater than 7.2. It also has the highest non ionized fraction (90%, more available to enter the brain) which accounts for its extremely fast onset time.

Question 26

What is the context senstitive half time of remifentanil?
a. 1 minute
b. 4 minutes
c. 10 minutes
d. 10 minutes

Answer 26

b. 4 minutes

The half time is about 4 minutes regardless of the duration of the infusion (due to rapid metabolism by tissue esterases)

Question 27

Remifentanil is safe for neuraxial anesthesia. True or False

Answer 27

False. The additive in remifentanil (glycine - an inhibitory neurotransmitter) can cause skeletal muscle weakness and should not be used for neuraxial anesthesia

Question 28

Which of the following medications can help treat opioid induced hyperalgesia following discontinuation of a remifentanil infusion. Select all that apply.
a. magnesium
b. morphine
c. ketamine
d. dexmedetomidine

Answer 28

a & c

Magnesium and ketamine are both helpful in reducing hyperalgesia. Ketamine is a NMDA receptor antagonist and magnesium acts as a plug at the NMDA receptor therefore limiting receptor activation

Question 29

Methadone decreases pain by all of the following mechanisms except:
a. mu receptor agonist
b. NMDA receptor antagonist
c. inhibits reuptake of monoamines in the synaptic cleft
d. kappa receptor agonist

Answer 29

d. kappa receptor agonist

Methadone decreases pain by the first 3 mechanisms and does not affect the kappa opioid receptors.

Question 30

Methadone can cause which of the following EKG changes?
a. prolonged PR interval
b. peaked T wave
c. presence of U wave
d. prolonged QT interval

Answer 30

d. prolonged QT interval

Methadone inhibits the delayed rectifier K ion channel which can lead to Torsades de pointes.