media lab Chem
All of the following are reasons for sample preparation prior to analysis EXCEPT for which statement?
To make the analytes more polar
Electron multiplier
Transforms single ions to many electrons
Injector
Vaporization of the extract
Which of the following is true of genotype screening in pharmacogenomics?
Which of the following is true of genotype screening in pharmacogenomics?
In GC/MS,electron ionization creates
a great deal of mass spectral information due to the high energy fragmentation produced.
Which of the following drugs is used primarily for the treatment of manic-depression?
lithium
LC/MS/MS electrospray ionization
produces much simpler mass spectra because ionization and fragmentation is produced with much lower energy ("soft ionization").
A drug that is administered IV will
reach peak level the quickest (15 - 30 minutes after injection/infusion).
Therapeutic window-
The range between a drug's effective dose and its toxic dose
When collecting a urine specimen for workplace drug testing, which of the following situations may indicate that the specimen has been tampered with or adulterated?
The specific gravity test result is 1.001 A specific gravity result of less than 1.003 is an indication of dilution of the specimen with water. Ranges: 1.003 and 1.025.
Pharmacogenomics (Pharmacogenetics
The study of how variations in the human genome affect a given individual's response to medications.
Which of the following statements is true regarding CYP450 enzymes?
They are able to make compounds more water-soluble and therefore enhance excretion.
A toxicology laboratory decides to develop an opiate method to be performed by LC/MS/MS. Why would they choose LC/MS/MS over GC/MS?
They want to avoid having to derivatize the samples.
Which of the following drug screens is LEAST likely to give false positive results?
Cocaine
Drug half-life
- The amount of time it takes for a drug's concentration in the body to decrease by 50%
Drug half-life
- The amount of time it takes for a drug's concentration in the body to decrease by 50%.
Pharmacokinetics
- The study of drug disposition in the body - how and when drugs enter the circulation, how long they stay there, and how they are eliminated
Pharmacokinetics
- The study of drug disposition in the body - how and when drugs enter the circulation, how long they stay there, and how they are eliminated.
Pharmacogenomics (Pharmacogenetics)
- The study of how variations in the human genome affect a given individual's response to medications
Urine is an ideal sample for drug testing for a number of reasons.
- long window of detection. -most extensively evaluated matrix for drug testing. -less expensive to analyze.
Toxic levels of lithium can cause lethargy, apathy, muscle weakness up to and including seizures and coma. What is the toxic level of lithium?
1.5-2 mmol/L
What blood alcohol concentration has been established as the statutory limit for operation of a motor vehicle in the United States?
80 mg/dL
A urine specimen is screened for drugs of abuse by EMIT. The enzyme activity is measured by a spectrometer and the signal is recorded in optical density (OD) units. The following results are obtained: Amphetamine: 25 Cocaine: 15 Oxycodone: -2 THC: 395 Opiates: -3 Which of the following statements are TRUE?
A drug confirmation will need to be performed for amphetamines, benzoylecognine, and THC.The positive result for drugs of the amphetamine class could be a false positive.
A person who is classified as an ultrarapid metabolizer (UM) would need __________ of a drug metabolized by that enzyme.
A higher dose
A drug with a molecular weight of 460 would yield which of the following?
A quasimolecular ion of 461 with high abundance by LC/MS/MS in positive mode. A molecular ion of 460 with low abundance by GC/MS. A quasi-molecular ion of 459 with high abundance by LC/MS/MS in negative mode.
Which of the following medications is known to cause Reye's Syndrome in children?
Acetylsalicylic acid/ aspirin
A physician needs to prescribe a drug to a patient but the drug has a narrow therapeutic window. He is concerned about possible toxic effects. To assess the upper concentration of such a drug, which time for drawing the specimen do you think makes the most sense?
Approximately one hour after an oral dose
The amount of time it takes for a drug's concentration in the body to decrease by 50% is referred to as?
Drug half-life
Bioavailability of an oral drug refers to the:
Fraction of the drug that is absorbed into systemic circulation.
Currently the MOST common method for the confirmation of serum barbiturates is:
Gas-liquid chromatography, mass spectrometry
Which of the following statements are TRUE concerning LC/MS/MS? (Select all that apply.)
Gives a high abundance of the quasimolecular ion in the mass spectra. Voltage applied to the probe creates ions.
Which of the following statements are TRUE concerning GC/MS? (Select all that apply.)
Gives a low abundance of the molecular ion in the mass spectra. Analytes eluting from the analytical column are subjected to violent fragmentation.
What type of anticoagulant is generally suitable for TDM analysis?
Heparin
A drug that is administered through which of the following routes will reach peak level the quickest?
IV
How does Aspirin (salicylic acid) affect platelet function?
Inhibiting cyclooxygenase
Ion source
Ionization of analytes
Albuterol is a fast-acting bronchodilator used acutely during asthma attacks. List the reasons below explains why TDM for albuterol is not available or common?
It is not a chronically used drug so toxicity is less likely. The half-life is short, and the drug is cleared quickly.I t has a wide therapeutic window. Compliance is not an issue with albuterol.
When is a trough blood sample for therapeutic drug monitoring usually obtained?
Just before the next scheduled dose
True statement about LC/MS/MS?
LC/MS/MS offers a much higher degree of specificity over GC/MS due to mass analysis in tandem. In LC/MS/MS, the highest m/z and the mass with the highest intensity is called the quasimolecular ion.
Quadrupole
Mass filtering
Which of the following drug combinations would yield positive drug screen results for both opiates and oxycodone?
Morphine and oxymorphone
You are collecting a blood specimen to be used for forensic (legal) alcohol testing. Which of the following must be done before you can start the specimen collection process?
Must inform the patient that the blood about to be collected is for alcohol testing
Which of the following scenarious is most likely to give a false negative result?
Oxymorphone present at 350 ng/mL in an oxycodone class screen where oxymorphone shows 25% cross-reactivity. The cutoff is 100 ng/mL.
The following factors would affect an orally-administered drug's absorption and/or distribution in the body?
Regional blood flow The integrity of the gastrointestinal (GI) tract The patient's age
An immunoassay drug screen in a clinical laboratory yields a result that is above the cutoff for Cocaine. Which of the following is the most appropriate action?
Results that are above the cutoff for immunoassay drug screens are generally reported as presumptive positive and reflexed for confirmation testing by a more specific platform, such as gas chromatography/mass spectrometry (GC/MS) or liquid chromatography/tandem mass spectrometry (LC/MS/MS ).
Chromatographic column
Separation of analytes
A patient is taking cimetidine for a stomach ulcer. This drug inhibits CYP2D6. The patient is now prescribed amphetamine for narcolepsy. Amphetamine is metabolized by CYP2D6. What would you predict?
Since cimetidine inhibits CYP2D6, less amphetamine will probably need to be given since it will not be able to be metabolized as readily.
A patient suffering from Celiac disease and Crohn disease (both inflammatory conditions of the GI tract) is given a new oral medication that has a narrow therapeutic window. Which of the following would be true?
TDM would be helpful to see how much drug has been absorbed. Blood collection for the TDM test should occur at least one hour after the administration of the oral drug. Measuring the serum level of the drug 15 minutes after the oral dose has been given is not sufficient time to allow for absorption
A patient suffering from Celiac disease and Crohn's disease (both inflammatory conditions of the GI tract) is given a new oral medication that has a narrow therapeutic window. Which of the following would be true?
TDM would be helpful to see how much drug has been absorbed. Blood collection for the TDM test should occur at least one hour after the administration of the oral drug. Measuring the serum level of the drug 15 minutes after the oral dose has been given is not sufficient time to allow for absorption
A positive result for which of the following drugs is least likely to indicate recent use of the drug?
THC
A urine sample screens positive for opiates (cutoff = 300 ng/mL) and negative for oxycodone (cutoff = 100 ng/mL). The confirmation yields a positive result for morphine and oxycodone. Which of the following is the most likely reason?
The confirmation cutoff is lower than the screen cutoff.
A physician needs to prescribe a drug to a patient but the drug has a narrow therapeutic window. He is concerned about possible toxic effects. To assess the upper concentration of such a drug, which time for drawing the specimen do you think makes the most sense?
The drug should be measured at a time corresponding to the peak concentration (not the trough). One to 2 hours after an oral dose is usually sufficient time for a drug to be absorbed and should correspond to peak concentration.
When considering therapeutic drug monitoring (TDM), what is the definition of bioavailability?
The fraction of the administered dose that eventually reaches its site of action is defined as its bioavailability.
Which is a FALSE statement about LC/MS/MS?
The ion source is operated under vacuum.
The concentration of a drug in the body is
a result of many variables and can be hard to predict.
Celiac disease and Crohn's disease are both inflammatory conditions of the GI tract that can cause
decreased absorption. Although an IV drug may be preferred, not all drugs are available as IV solutions; until low absorption is confirmed, an oral drug may be tried.
Which of the following drugs is used to treat congestive heart failure?
digoxin
Cloned Enzyme Donor Immunoassay (CEDIA),
drug bound to the enzyme donor and drug in the sample compete for antibody binding sites.
Enzyme Multiplied Immunoassay Technique (EMIT),
drug labeled with the enzyme G6PD and drug in the sample compete for antibody binding sites.
Enzyme-Linked Immunosorbent Assay (ELISA),
drug or metabolite in the sample and drug or metabolite labeled with enzyme compete for binding sites on the antibody that is absorbed to the surface of the sample well.
Thin-layer chromatography is particularly useful as a tool in the identification of:
drugs
Clinical toxicology
focuses on the relationships between xenobiotics and disease states. This area emphasizes not only diagnostic testing but also therapeutic intervention.
Which type of toxicology is primarily concerned with medical and legal consequences of exposure to chemicals and drugs?
forensic toxicology
When considering therapeutic drug monitoring, which two organ systems are associated with drug elimination?
hepatic & renal
A CYP2D6 ultrarapid metabolizer (UM) would require ___________ dose of a drug that is metabolized by CYP2D6 than a CYP2D6 extensive metabolizer (EM).
higher
Which of the following is the most common technique that is used by clinical laboratories for therapeutic drug monitoring?
imunuassay
Environmental toxicology
includes the evaluation of environmental chemical pollutants and their impact on human health.
Lithium
is commonly used in the treatment of manic depressive patients. Lithium exerts a dual effect on receptors for the neurotransmitter glutamate; acting to keep the amount of glutamate active between cells at a stable, healthy level, neither too much nor too little. This allows for a mood stabilization for these patients.
Forensic toxicology
is primarily concerned with the medical and legal consequences of exposure to chemicals and drugs. A major focus of forensic toxicology is establishing and validating the analytic performance of test methods used to generate evidence in legal situations, including cause of death.
If a drug is given at intervals that are the same as its half-life, approximately how long will it take the drug to reach steady state?
t will take about 5 half-lives to reach steady state.
LC/MS/MS is more specific than GC/MS due to
the multiple layers of mass filtering created by the use of multiple mass analyzers.
The range between a drug's effective dose and its toxic dose is called?
therapeutic window
Point of Care drug testing devices
there is competition between dye conjugated antibodies binding to drug present in the urine sample and dyed conjugated antibodies binding to drug that is bound to a porous membrane.
Descriptive toxicology
uses the results from animal experiments to predict what level of exposure will cause harm in humans.
The cross-reactivity for methamphetamine in an amphetamine class immunoassay is 5 times less than that of amphetamine. The cutoff for the test is 200 ng/mL. What concentration would methamphetamine need to be present at to give a positive screen?
≥ 1,000 ng/mL
