Deck 8: Fundamentals of Toxicology

Question 1

A xenobiotic substance is one that is

A) not normally found in the body
B) a metabolizing enzyme
C) is normally found in the body at high concentrations
D) plays a role in digestion and absorption
E) None of the above

Answer 1

E

Question 2

Which of the following mode(s) of ingestion do not involve first pass metabolism?

A) oral ingestion and intravenous ingestion
B) oral ingestion and smoking
C) smoking and intravenous injection
D) more than one of the above
E) None of the above

Answer 2

C

Question 3

A pain reliever formulation contains 8 mg of codeine phosphate (FW 397.4 g/mole). If a person takes two tablets, how many milligrams of codeine do they ingest? The formula weight of codeine is 299.4 g/mol.

A) 16
B) less than 1
C) 8
D) 12

Answer 3

D

Question 4

What is the force that drives passive diffusion of a molecule through a lipid bilayer?

A) a concentration gradient
B) Energy from the ATP cycle
C) ion trapping
D) a polarity gradient
E) None of the above

Question 5

What form must a drug with an ionizable center be in to successfully partition across a lipid bilayer?

A) BH⁺/HA
B) BH⁺/A^-
C) B/HA
D) B/A^-
E) None of the above

Question 6

Drugs can move across a lipid bilayer from a region of low concentration to a region of high concentration by

A) passive transport
B) active transport
C) facilitated diffusion
D) vaporization
E) None of the above

Question 7

When a drug passes in a gap between two adjacent cells, this is called

A) transcellular transport
B) vapor intrusion
C) paracellular transport
D) active transport
E) None of the above

Question 8

Assume these are the approximate pH ranges in the GI tract and that pH is the only factor being considered. In what region will the pH conditions be most favorable for absoption of an acidic drug with a pKa of 5?

A) Region 1
B) Region 2
C) Region 3
D) Equally in all three regions
E) None of the above

Question 9

Assume these are the approximate pH ranges in the GI tract and that pH is the only factor being considered. In what region will the pH conditions be most favorable for absorption of a basic drug with a pKa of 5.7?

A) Region 1
B) Region 2
C) Region 3
D) Equally in all three regions
E) None of the above

Question 10

Some drugs like MDMA (Ecstasy, pKa 9.9) are so basic that they do not exist in any appreciable quantities in the neutral B form in the digestive tract. Yet, they are still absorbed. What factors allow for this?

A) Very large surface area of the GI tract
B) Rapid removal of any B molecules that do exist and transit the lipid bilayer
C) Movement of the liquid phases on both sides of the lipid bilayer
D) All of the above
E) None of the above

Question 11

The volume of distribution (V_d) of a drug is

A) the minimum volume of plasma needed to completely dissolve it
B) the maximum volume of water in a person's body available to dissolve a drug
C) a measure of the solubility as a function of the pH gradient
D) an expression that reflects how a drug distributes once absorbed into the bloodstream
E) None of the above

Question 12

A person weighing 145 lbs ingests a tablet containing 5 mg of a drug. A blood draw shows a Cp,max of 35 mg/L. What is the V_d of this drug in L/kg? Assume that bioavailability is 100%

A) 0.9
B) 0.4
C) 26
D) 2
E) None of the above

Question 13

Calculate the peak plasma concentration that results when a man weighing 104 kg ingests a 10. mg of a drug. Assume no loss to first pass metabolism and report your result in ug/L

A) 24
B) 5.2
C) 15
D) 0.02
E) None of the above

Question 14

Estimate the initial dose in mg of a drug if the Cp,max is found to be 0.25 mg/L and the V_d is 1.4. The person weighs 91 kg. Assume no loss to first pass metabolism

A) 5.1
B) 1.3
C) 45
D) 32
E) None of the above

Question 15

The drug methylphenidate is used to treat ADD. Its bioavailability is 30% and the V_d is 11. L/kg. If a teenager weighing 79 kg takes 2 tablets, each containing 20. mg of the drug, calculate the Cp,max in ug/L.

A) 0.07
B) 14
C) 37
D) 4.9
E) None of the above

Question 16

A drug that has ________ plasma protein binding (PPB) will tend to have a ______ volume of distribution (V_d)

A) low, higher
B) low, lower
C) high, lower
D) high, higher
E) None of the above

Question 17

The elimination of most drugs of forensic interest can be modeled using what type of kinetics?

A) zero-order
B) first-order
C) second order
D) combinations of zero and second order
E) None of the above

Question 18

A person weighing 175 lbs takes a drug as part of an ingestion study. The Cp,max of the drug is 20 ug/L and the half-life is 2 hours. What will the plasma concentration (ug/L) be 90 minutes after the peak plasma concentration was reached? Assume first order elimination.

A) 12
B) less than 1
C) 10
D) 34
E) None of the above

Question 19

In a typical phase 1 metabolic transformation, a drug molecule tends to become

A) inert; no longer pharmacologically active
B) less polar
C) larger
D) more polar
E) None of the above

Question 20

What occurs during phase 2 metabolism?

A) a polar group or groups is removed from the molecule
B) a polar group is bonded to the molecule
C) a functional group is altered
D) oxidation of any aromatic rings
E) None of the above

Question 21

Morphine-6-glucuronide is an example of

A) a phase 1 metabolite
B) a phase 2 metabolite
C) a CYP
D) a UGT
E) None of the above

Question 22

Most of the phase 1 metabolic reactions of forensic interest are what type of enzymes?

A) CYPs
B) UGTs
C) Dehydrogenases
D) sulfatases
E) None of the above

Question 23

If a substance binds to the active site of an enzyme like a CYP and blocks a drug from docking there, this is called

A) non-competitive inhibition
B) induction
C) abduction
D) competitive inhibition
E) None of the above

Question 24

Enzyme inhibition frequently leads to

A) induction
B) drug-drug interactions
C) phase 2 metabolism
D) exduction
E) None of the above

Question 25

The ED50 is

A) the extended dose of the top 50 drugs by sales
B) the dose required to achieve a plasma concentration of 50 mg/L
C) the effective dose of a drug for 50% of a population
D) more than one of the above
E) None of the above

Question 26

Which of these factors could lead to death even if a person ingests less than the LD50 of a drug?

A) being a poor metabolizer
B) being less tolerant to the drugs effects
C) being an extensive metabolizer
D) more than one of the above
E) None of the above

Question 27

After a neurotransmitter is released and binds to a receptor, it is often returned to the originating neuron. This process is called

A) activation
B) reuptake
C) deactivation
D) magic
E) None of the above

Question 28

The drug Paxil is a selective serotonin reuptake inhibitor (SSRI) used to treat anxiety and other conditions. The neurotransmitter serotonin is associated with mood and increases in its levels alleviates these symptoms. What is a reasonable explanation for how this drug works?

A) It causes more serotonin to be released
B) it prevents the neurotransmitter serotonin from being reabsorbed, thus increasing the level of serotonin available
C) It causes less serotonin to be released
D) It binds with the serotonin receptors
E) None of the above

Question 29

Opioids, like fentanyl, bind with the mu opiate receptors in the brain. Fentanyl is classified as an ________ of these receptors

A) agonist
B) inhibitor
C) antagonist
D) inducer
E) None of the above