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30 Cards in this Set
- Front
- Back
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In the fluorescence polarization method of detecting a drug in serum, is an increase or decrease in fluorescence indicative of the presence of the drug?
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A decrease of fluorescence indicates th e presence of drug in the sample.
Fluorescence, which a rises from immobilized antibody-reagent drug fluorescent probe complexes, decreases when patient drug binds to the reagent antibodies and frees up reagent drug bound to a fluorescent probe molecule to tumble in solution |
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What technique is considered the gold standard for detection and quantitation of volatile drugs and poisons?
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This is gas-chromatography-mass spectroscopy (GC-MS).
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Drugs of abuse are usually ___derivatives, with the exception of barbiturates, which are acids.
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Most drugs of abuse are amine derivatives and are basic, except barbiturates.
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What advantages does high-performance liquid chromatography (HPLC) offer over traditional thin-layer chromatography (TLC) in the detection of tricyclic antidepressants (TCAs)?
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HPLC is quantitative and allows for a sharp separation of similar compounds, such as parent compounds and their metabolites. However, capillary electrophoresis, a variation of TLC, now offers some of the advantages of HPLC.
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Briefly state the principle of mass spectroscopy
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High temperatures or electron bomba rd ment of a molecular species will cause the molecules to lose electrons, becoming ionized into cations. These molecule-ions will decompose into characteristic fragments, and these fragments are present in characteristic ratios, resulting in the fingerprint pattern unique to a particular compound
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What is the common chemical structure of morphine, codeine, and heroin ?
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All are basic, tertiary amines containing a benzene ring.
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What is the Jess active metabolite of cocaine which may be detected in the urine up to 24-48 hours after cocaine use, depending on the method of testing?
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This is benzoylecgonine.
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True/False. Both heroin and methadone act by binding to mu-receptors in the central nervous system and have a similar chemical structure.
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False. Methadone is a nonbicyclic drug, but both act on the mu-receptor.
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Benzodiazepines appear to work by inducing the secretion of what neurotransmitter?
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This is gamma-aminobutyric acid (GABA).
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What receptor, newly discovered, does phencyclidine bind to, possibly accounting for the psychosis seen in many users?
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This is the sigma-receptor.
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Why is naloxone an effective antidote for propoxyphene toxicity?
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Propoxyphene has pharmacologic properties similar to those of the opiates, although it is structurally quite different.
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What are the two major metabolites of cannabis detected in urine?
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These are delta-9-carboxytetrahydrocannabinol (delta-9-carboxy-THC) and 11-hydroxy-delta-9-THC.
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To what chemical class does lysergic acid diethylamide belong?
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LSD is a semisynthetic indolalkylamine
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A steady state of drug concen tration is reached in____half-lives.
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Steady state is four-plus half-lives.
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What is the mechanism by which procainamide causes a lupus-like syndrome?
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WBCs convert procainamide to a metabolite which can covalently bind to the membrane proteins of monocytes and macrophages. This then stimulates the production of antibodies. Also, this metabolite can mimic a portion of the histone protein, leading to the production of antihistone antinuclear antibodies.
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Why is phenobarbital contraindicated in patients with acute intermittent porphyria?
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Barbiturates enhance the synthesis of delta-aminolevulinc acid synthetase.
Since AlP patients cannot readily continue in the heme synthetic pathway past porphobilinogen because they lack PBG deaminase, they accumulate both ALA and PBG when given barbiturates. |
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What is the clinical implication of the serum half-life of phenytoin being dose dependent?
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Excretion does not follow first-order kinetics. Thus, small increases in dosage can result in great increases in serum concentration, causing toxicity.
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True/False. The half-life of theophylline is shorter in smokers than nonsmokers, and shorter still in children
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True. The text in this edition does not address the half-life in children, but it is shorter than in adults, no matter their habits.
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Clinical Consultation: A 16-yea r-old female presents to the ER remorseful about a suicide attempt by acetaminophen overdose 12 hours ago. She weighs 60 kg and said she took 20 extra-strength (500 mg) tablets. How likely is it tha t this represents a toxic dose?
Her dose: Toxic dose at her weight: Likelihood: |
Quite likely. She ingested 10,000 mg and a toxic dose for her weight is 8,400 mg.
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The optimal trough levels for cyclosporin are 50-300ng/ mL. What kind of toxicity is often seen at trough levels greater than 500ng/dL/
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Nephrotoxicity occurs at this high level.
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Hyperactive deep tendon reflexes, choreaathetoid movements, and persistent vomiting in a patient with bipolar disorder who states that his last dose of lithium was abou t 12 hours ago probably has (give qualitative estimate)_____
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These signs constitute moderate to severe toxicity. It is likely that his lithium level is between 2.5-3.5mEq/L. Note, though, that Henry stresses th a t lithium levels do not correlate all that well with clin ical presentations.
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What are the two cardinal signs of TCA overdose?
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Dry skin and, in particular, dilated pupils are the two key signs.
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Clinical Consultation: Twelve hours a fter ingesting an unknown quantity of aspirin tablets, a child has a serum salicylate concentration of 62 mg/dL. Using the nomogram, what level of toxicity is this?
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Using the nomogram, this would be mild- moderate toxicity
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What is the role of the oxidants amyl nitrite or sodium nitrite in treatment of cyanide poisoning?
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Either of these agents will convert hemoglobin (Fe2+) to methemoglobin (Fe 3 +).
The cyanide ion in CN- binds reversibly to cytochrome A3 to inhibit cellular respiration, but it can be removed with methemoglobin. Methemoglobin competes with ferricytochrome A3 to form a complex with the CN- ion, cyanomethemoglobin, which can then be converted to thiocyanate and excreted in the urine. |
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What metabolite of ethylene glycol correlates directly with symptomatology and mortality and is the major contributor to the characterisitc high anion gap seen in toxic ingestions?
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This is glycolic acid.
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Clinical Consultation: 45 minutes after ingesting ant poison, a 6-year-old boy complains of burning in his mouth and throat. He is vomiting and passes bloody stool. An odor of garlic is present on his breath. What toxin did he ingest?
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This is arsenic. If the garlic odor is not given as a clue, then the history of insecticides/ant poison is a helpful clue to arsenic as the agent.
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Which of the four chemical forms of mercury is well absorbed after oral ingestion and typically causes GI symptoms and kidney damage, including acute tubular necrosis?
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This is mercuric salt, in the Hg2+ form. This is one of the inorganic forms of mercury.
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What form of iron is toxic to hepatic cells and results in shock and lactic acidosis?
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Elemental iron, Fe, is very toxic when free in the body. A high enough dose overwhelms the transferrin sites.
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List t he four enzymes in the heme synthetic pathway that are inhibited by lead.
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These are ALA synthetase, ALA dehydratase, coproporphyrinogen decarboxylase, and ferrochelatase.
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In cases of chronic lead poisoning, wha t technique allows for the determination of cumulative lead burden?
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As 96% of the total body burden of lead is in bone, a fluorescence X-ray is more useful than blood lead levels. Lead does not stay in the blood very long, so serum levels are really helpful in acute exposures rather than chronic exposures
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