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Flashcards in Toxicology Deck (15)
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1

What are the various specimens you can use to evaluate for drug use?

urine
blood
hair
saliva
sweat
nails

2

Why do we usually do urine drug screens?

drugs and metabolites tend to be higher longer in the urine than serum

3

What is the basis for most of the drug screening assays?

most are immunoassay based, so use antibodies to identify drug or drug class

because of this, cross-reactivity is common and critical to recognize

4

In general, what is the basis for confirmatory testing?

usually gas or liquid chromatography mass spect

(the nice thing about them is they can identify drugs with certainty, but you need to know the specific drug to test for it - not good for screening)

5

Urine from what time of day is the most helpful for drug testing?

early morning, because that's when the drug will be at the highest concentration

6

What are some tip-offs that someone has falsified their urine sample?

excessive bubble formation
it's cold
the pH is less than 3 or more than 11
the specific gravity is less than 1.002 (diluted) or greater than 1.020
Creatinine is less than 5 mg/cL

7

What does the urine drug screen look for specifically when screening for cannabinoids?

11-nor-delta-9-THC-carboxylic acid

also metabolite of THC

8

Why not just look for THC?

it's highly soluble in lipids so has slow excretion into urine whereas the metabolites get there faster

9

A single use of marijuana can result in a positive urine screen for how long?

up to 1 week

10

Long-term use of marijuana can result in a positive screen for how long?

up to 46 days

11

What are three common drugs that have been shown to cross-react with cannabinoid immunoassays?

NSAIDs (yikes)
efavirenz
PPIs
some antibiotics (quinolones)

Also hemp-containing foods and eye drops like visine!

12

Why can someone on methadone have a negative opiate screen?

methadone is an opioid that interacts with the opioid receptor but has no chemical similarity to opiates and won't cross-react with the reagent

13

What do most amphetamine screens look for?

most do amphetamine and methamphetamine, but others do MDMA and MDA

others do the stimulants more broadly

14

WHat are some drugs that will cause clinical false positives on amphetamine screens?

adderall

dexedrin

methamphetamine

selegiline

famprofazone (apparently it's an alagesic and antipyretic)

15

True or false: cross-reactivity allows for all benzodiazepines to be tested for using the same antibody?

nope

most of the benzo screening assays use antibodies directed against a single benzo