6.8 Toxicology and Therapeutic Drug Monitoring

Question 1

In which of the following cases is qualitative analysis of the drug usually adequate?
A. To determine whether the dose of a drug with a low therapeutic index is likely to be toxic
B. To determine whether a patient is complying with the physician’s instructions
C. To adjust dose if individual differences or disease alter expected response
D. To determine whether the patient has been taking amphetamines

Answer 1

D. To determine whether the patient has been taking amphetamines

Question 2

The term pharmacokinetics refers to the:
A. Relationship between drug dose and the drug blood level
B. Concentration of drug at its sites of action
C. Relationship between blood concentration and therapeutic response
D. The relationship between blood and tissue drug levels

Answer 2

A. Relationship between drug dose and the drug blood level

Question 3

The term pharmacodynamics is an expression of the relationship between:
A. Dose and physiological effect
B. Drug concentration at target sites and physiological effect
C. Time and serum drug concentration
D. Blood and tissue drug levels

Answer 3

B. Drug concentration at target sites and physiological effect

Question 4

The study of pharmacogenomics involves which type of testing?
A. Familial studies to determine the inheritance of drug resistance
B. Testing drugs with cell cultures to determine the minimum toxic dosage
C. Testing for single nucleotide polymorphisms known to affect drug metabolism
D. Comparison of dose–response curves between family members

Answer 4

C. Testing for single nucleotide polymorphisms known to affect drug metabolism

Question 5

Select the five pharmacologic parameters that determine serum drug concentration.
A. Absorption, anabolism, perfusion, bioactivation, excretion
B. Liberation, equilibration, biotransformation, reabsorption, elimination
C. Liberation, absorption, distribution, metabolism, excretion
D. Ingestion, conjugation, integration, metabolism, elimination

Answer 5

C. Liberation, absorption, distribution, metabolism, excretion

Question 6

Which route of administration is associated with 100% bioavailability?
A. Sublingual
B. Intramuscular
C. Oral
D. Intravenous

Answer 6

D. Intravenous

Question 7

The phrase “first-pass hepatic metabolism” means that:
A. One hundred percent of a drug is excreted by the liver
B. All drug is inactivated by hepatic enzymes after one pass through the liver
C. Some drug is removed from the portal circulation, reducing bioavailability
D. The drug must be metabolized in the liver to an active form

Answer 7

C. Some drug is removed from the portal circulation, reducing bioavailability

Question 8

Which formula can be used to estimate dosage needed to give a desired steady-state blood level?
A. Dose per hour = clearance (milligrams per hour) × average concentration at steady state ÷ f
B. Dose per day = fraction absorbed – fraction excreted
C. Dose = fraction absorbed × (1/protein-bound fraction)
D. Dose per day = half-life × log Vd (volume distribution)

Answer 8

A. Dose per hour = clearance (milligrams per hour) × average concentration at steady state ÷ f

Question 9

Which statement is true regarding the volume distribution (Vd) of a drug?
A. Vd is equal to the peak blood concentration divided by the dose given
B. Vd is the theoretical volume in liters into which the drug distributes
C. The higher the Vd, the lower is the dose needed to reach the desired blood level of drug
D. The Vd is the principal determinant of the dosing interval

Answer 9

A. Vd is equal to the peak blood concentration divided by the dose given

Question 10

For drugs with first-order elimination, which statement about drug clearance is true?
A. Clearance = elimination rate ÷ serum level
B. It is most often performed by the liver
C. It is directly related to half-life
D. Clearance rate is independent of dose

Answer 10

A. Clearance = elimination rate ÷ serum level

Question 11

Which statement about steady-state drug levels is true?
A. The absorbed drug must be greater than the amount excreted
B. Steady state can be measured after two elimination half-lives
C. Constant IV infusion will give the same minima and maxima as an oral dose
D. Oral dosing intervals give peaks and troughs in the dose–response curve

Answer 11

D. Oral dosing intervals give peaks and troughs in the dose–response curve

Question 12

If too small a peak–trough difference is seen for a drug given orally, then:
A. The dose should be decreased
B. Time between doses should be decreased
C. Dose interval should be increased
D. Dose per day and time between doses should be decreased

Answer 12

C. Dose interval should be increased

Question 13

If the peak level is appropriate but the trough level too low at steady state, then the dose interval should:
A. Be lengthened without changing the dose per day
B. Be lengthened and dose rate decreased
C. Not be changed, but dose per day increased
D. Be shortened, but dose per day not changed

Answer 13

D. Be shortened, but dose per day not changed

Question 14

If the steady-state drug level is too high, the best course of action is to:
A. Decrease the dose
B. Decrease the dose interval
C. Decrease the dose and decrease the dose interval
D. Change the route of administration

Answer 14

A. Decrease the dose

Question 15

When should blood samples for trough drug levels be collected?
A. 30 minutes after peak levels
B. 45 minutes before the next dose
C. 1 to 2 hours after the last dose
D. Immediately before the next dose is given

Answer 15

D. Immediately before the next dose is given

Question 16

Blood sample collection time for peak drug levels:
A. Varies with the drug, depending on its rate of absorption
B. Is independent of drug formulation
C. Is independent of the route of administration
D. Is 30 minutes after a bolus IV injection is completed

Answer 16

A. Varies with the drug, depending on its rate of absorption

Question 17

Which could account for drug toxicity following a normally prescribed dose?
A. Decreased renal clearance caused by kidney disease
B. Discontinuance or administration of another drug
C. Altered serum protein binding caused by disease
D. All of these options

Answer 17

D. All of these options

Question 18

Select the elimination model that best describes most oral drugs given at therapeutic doses.
A. One compartment, linear first-order elimination
B. Michaelis-Menton or nonlinear elimination
C. Two compartment with a biphasic elimination curve
D. Logarithmic elimination

Answer 18

A. One compartment, linear first-order elimination

Question 19

Drugs rapidly infused intravenously usually follow which elimination model?
A. One compartment, first order
B. One compartment, logarithmic
C. Biphasic or two compartment with serum level rapidly falling in the first phase
D. Michaelis-Menton or concentration-dependent elimination

Answer 19

C. Biphasic or two compartment with serum level rapidly falling in the first phase

Question 20

Which fact must be considered when evaluating a patient who displays signs of drug
toxicity?
A. Drug metabolites (e.g., N-acetylprocainamide) may need to be measured as well as parent drug
B. If the concentration of total drug is within therapeutic limits, the concentration of free drug
cannot be toxic
C. If the drug has a wide therapeutic index, then it will not be toxic
D. A drug level cannot be toxic if the trough is within the published therapeutic range

Answer 20

A. Drug metabolites (e.g., N-acetylprocainamide) may need to be measured as well as parent drug

Question 21

When a therapeutic drug is suspected of causing toxicity, which specimen is the most appropriate for an initial investigation?
A. Trough blood sample
B. Peak blood sample
C. Urine at the time of symptoms
D. Gastric fluid at the time of symptoms

Answer 21

B. Peak blood sample

Question 22

For a drug that follows first-order pharmacokinetics, adjustment of dosage to achieve the desired blood level can be made by using which formula?

Answer 22

A

Question 23

For which drug group are both peak and trough measurements usually required?
A. Antiarrhythmics
B. Analgesics
C. Tricyclic antidepressants
D. Aminoglycoside antibiotics

Answer 23

D. Aminoglycoside antibiotics

Question 24

Which of the following urine samples should be accepted for testing when processing samples for drugs of abuse (DAUs)?
A. Urine of abnormal color
B. Urine with an abnormal odor
C. Container with seal not applied across the lid
D. Sample with a volume of 50 mL

Answer 24

D. Sample with a volume of 50 mL

Question 25

The enzyme-multiplied immunoassay technique (EMIT) for DAUs uses an:
A. Antibody conjugated to a drug
B. Enzyme conjugated to an antibody
C. Enzyme conjugated to a drug
D. Antibody bound to a solid phase

Answer 25

C. Enzyme conjugated to a drug

Question 26

Which statement about EMIT is true?
A. Enzyme activity is inversely proportional to drug level
B. Formation of NADH is monitored at 340 nm
C. ALP is the commonly used conjugate
D. Assay use is restricted to serum

Answer 26

B. Formation of NADH is monitored at 340 nm

Question 27

Which statement regarding cloned enzyme donor immunoassay (CEDIA) is true?
A. The enzyme used is G-6-PD
B. The enzyme donor and acceptor molecules are fragments of β-galactosidase
C. Drug concentration is inversely related to fluorescence
D. The antibody is covalently linked to the enzyme donor

Answer 27

B. The enzyme donor and acceptor molecules are fragments of β-galactosidase

Question 28

Which statement is true regarding particle-enhanced turbidimetric inhibition immunoassay methods for therapeutic drugs?
A. Drug concentration is proportional to light scatter
B. Magnetic separation is needed to remove unbound conjugate
C. When particle-bound drug binds to antibody, light scattering is increased
D. Two antibodies to the drug are needed

Answer 28

C. When particle-bound drug binds to antibody, light scattering is increased

Question 29

Quantitation of a drug by GC-MS is usually performed in which mode?
A. Total ion chromatography
B. Selective ion monitoring
C. Ion subtraction
D. Selective reaction monitoring

Answer 29

B. Selective ion monitoring

Question 30

SITUATION: A urine sample is received in the laboratory with the appropriate custody control form and a request for DAU screening. Which test result would be cause for rejecting the sample?
A. Temperature after collection 95°F
B. pH 5.0
C. Specific gravity 1.005
D. Creatinine 5 mg/dL

Answer 30

D. Creatinine 5 mg/dL

Question 31

Which substance has the longest detection time in urine?
A. Amphetamines
B. Cocaine
C. Benzodiazepines
D. Marijuana

Answer 31

D. Marijuana

Question 32

Which statement about the measurement of carboxyhemoglobin is true?
A. Treatment with alkaline dithionite is used to convert carboxyhemoglobin to oxyhemoglobin
B. Oxyhemoglobin has no absorbance at 540 nm, but carboxyhemoglobin does
C. Polychromic analysis is used to eliminate interference by oxyhemoglobin
D. Carboxyhemoglobin can be measured by potentiometry

Answer 32

C. Polychromic analysis is used to eliminate interference by oxyhemoglobin

Question 33

Which of the following statements about blood alcohol measurement is correct?
A. Symptoms of intoxication usually begin when the level exceeds 0.05% weight per volume (w/v)
B. The skin puncture site should be disinfected with isopropanol
C. The reference method is based upon enzymatic oxidation of ethanol by ADH
D. GC methods require extraction of ethanol from serum

Answer 33

A. Symptoms of intoxication usually begin when the level exceeds 0.05% weight per volume (w/v)

Question 34

Which specimen is the sample of choice for lead screening?
A. Whole blood
B. Hair
C. Serum
D. Urine

Answer 34

A. Whole blood

Question 35

Which of the following enzymes can be used to measure plasma or serum salicylate?
A. Peroxidase
B. Salicylate esterase
C. Salicylate hydroxylase
D. p-Aminosalicylate oxidase

Answer 35

C. Salicylate hydroxylase

Question 36

Which of the following tests is least essential to the operation of an ED at a general hospital?
A. Carboxyhemoglobin
B. Osmolality
C. Salicylate
D. Lead

Answer 36

D. Lead

Question 37

Which of the following trace elements is considered an essential micronutrient?
A. Thallium
B. Aluminum
C. Mercury
D. Selenium

Answer 37

D. Selenium

Question 38

When measuring trace metals other than lead in blood, what type of tube should be used?
A. Navy blue top
B. Green top
C. Purple top
D. Red top

Answer 38

A. Navy blue top

Question 39

Which whole blood level is suggestive of excessive exposure to lead in children but not adults?
A. 4 μg/dL
B. 14 μg/dL
C. 28 μg/dL
D. 32 μg/dL

Answer 39

B. 14 μg/dL

Question 40

What are the likely laboratory findings in a person suspected of having Wilson disease?
A. Blood copper and ceruloplasmin low, urinary copper excretion high
B. Blood and urine copper concentration high, ceruloplasmin low
C. Blood and urine copper concentration high, ceruloplasmin high
D. Blood and urine copper concentration low, ceruloplasmin low

Answer 40

A. Blood copper and ceruloplasmin low, urinary copper excretion high