Chemistry 6.8 Toxicology and Therapeutic Drug Monitoring Flashcards
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
D. To determine whether the patient has been taking amphetamines
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
A. Relationship between drug dose and the drug blood level
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
B. Drug concentration at target sites and physiological effect
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
C. Testing for single nucleotide polymorphisms known to affect drug metabolism
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
C. Liberation, absorption, distribution, metabolism, excretion
Which route of administration is associated with 100% bioavailability?
A. Sublingual
B. Intramuscular
C. Oral
D. Intravenous
D. Intravenous
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
C. Some drug is removed from the portal circulation, reducing bioavailability
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)
A. Dose per hour = clearance (milligrams per hour) × average concentration at steady state ÷ f
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
A. Vd is equal to the peak blood concentration divided by the dose given
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
A. Clearance = elimination rate ÷ serum level
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
D. Oral dosing intervals give peaks and troughs in the dose–response curve
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
C. Dose interval should be increased
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
D. Be shortened, but dose per day not changed
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
A. Decrease the dose
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
D. Immediately before the next dose is given
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
A. Varies with the drug, depending on its rate of absorption
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
D. All of these options
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
A. One compartment, linear first-order elimination
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
C. Biphasic or two compartment with serum level rapidly falling in the first phase
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
A. Drug metabolites (e.g., N-acetylprocainamide) may need to be measured as well as parent drug
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
B. Peak blood sample
For a drug that follows first-order pharmacokinetics, adjustment of dosage to achieve the desired blood level can be made by using which formula?
A. New dose = (current dose/concentration at steady state) x desired concentration
B. New dose = (current dose/desired concentration) x concentration at steady state
C. New dose = (concentration at steady state/desired concentration) x half-life
D. New dose = (concentration at steady state/current dose) x desired concentration
A. New dose = (current dose/concentration at steady state) x desired concentration
Most drugs follow first-order pharmacokinetics—that is, the clearance of drug is linearly related to the drug dose. The dose of such drugs can be adjusted by multiplying the ratio of the current dose to blood concentration by the desired drug concentration, provided the blood concentration is measured at steady state.
For which drug group are both peak and trough measurements usually required?
A. Antiarrhythmics
B. Analgesics
C. Tricyclic antidepressants
D. Aminoglycoside antibiotics
D. Aminoglycoside antibiotics
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
D. Sample with a volume of 50 mL
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
C. Enzyme conjugated to a drug
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
B. Formation of NADH is monitored at 340 nm
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
B. The enzyme donor and acceptor molecules are fragments of β-galactosidase
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
C. When particle-bound drug binds to antibody, light scattering is increased
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
B. Selective ion monitoring
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
D. Creatinine 5 mg/dL
Normal ranges:
temperature: 90°F–100°F
pH: 4.5–8.0
specific gravity: 1.003–1.019
creatinine: 20 mg/dL or greater
Which substance has the longest detection time in urine?
A. Amphetamines
B. Cocaine
C. Benzodiazepines
D. Marijuana
D. Marijuana
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
C. Polychromic analysis is used to eliminate interference by oxyhemoglobin
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
A. Symptoms of intoxication usually begin when the level exceeds 0.05% weight per volume (w/v)
Which specimen is the sample of choice for lead screening?
A. Whole blood
B. Hair
C. Serum
D. Urine
A. Whole blood
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
C. Salicylate hydroxylase
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
D. Lead
Which of the following trace elements is considered an essential micronutrient?
A. Thallium
B. Aluminum
C. Mercury
D. Selenium
D. Selenium
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
A. Navy blue top
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
B. 14 µg/dL
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
A. Blood copper and ceruloplasmin low, urinary copper excretion high
