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Flashcards in Toxicology Deck (35):
1

What allows for longer detection times, urine or serum?

urine

2

What is an immnoassay based screening assay?

Rely on ANTIBODIES ABILITY to identify the drug/drug class.
CROSS REACTIVITY (rxn between two different molecules) is critical.


An immunoassay is a biochemical test that measures the presence or concentration of a macromolecule or a small molecule in a solution through the use of an antibody (usually) or an antigen (sometimes).

3

What can be used for confirmation testing?

gass chromatography mass spectrometry (GC/MS)
Liquid chromatography mass spect (LC/MS, LC/MS/MS)

PRO: they identify drugs with certainty
CON: you ahve to look for specific drugs

4

What are characteristics of normal urine?

• Appearanceandcolor
– Pale yellow to clear
– Early morning urine provides most reliable information.
– Unusual colors can be due to medications, foods, or diseases.
• Temperature (32°C to 38°C)
• pH (4.5 to 8.0)
• Specificgravity(greaterthan1.002andlessthan 1.020)
• Creatinine(greaterthan20mg/dL)

5

What are signs of phony urine samples?

• Excessive bubble formation
• Cold
• pH less than 3 or greater than 11
• Specific gravity less than 1.002 or greater than 1.020
• Creatinine less than 5 mg/dL

6

What are cannabinoids?

unique set of chemicals found in cannabis plant

most psychoactive chemical is delta 9 THC

7

What does the UDS detect of cannabinoids?

11‐nor‐delta‐9‐THC‐ carboxylic acid (9‐carboxyl‐THC) and metabolites of THC.

8

A single use of cannabis can have a positive urine test up to...

1 week

9

long term use can produce positive results for up to...

46 days

10

Is passive exposure of cannabis possible?

possible but unlikely

11

How does an opiates screening assay work?

• Designed to look for illicit opiate use – Morphine
• More practically thought of as a morphine immunoassay

Antibody’s cross‐reactivity allows for detection of other opiates.
– Codeine
– Hydrocodone
– Hydromorphone – Oxycodone
– Oxymorphone

12

What drugs have been shown to cross-react with cannabinoid immunoassay?

efavirenz
PPIs
Hemp containing foods
eye drops (visine)

13

what is the difference between an opiate vs opioid?

• Opiates
– Naturally‐occurring or semi‐synthetic alkaloids derived from opium (the dried juice from the seeds of the poppy Papaver somniferum)
• Opioids
– Interact with the opioid receptors – No chemical similarity to opiates

14

opium
morphine codeine

from opium

15

heroin, hydrocodone, hydromorphone, oxycodone

semisynthetic

16

methadone, propoxyphene, merperidine, fentanyl

synthetic

17

methadone, propoxyphene, merperidine, fentanyl

synthetic

18

Major metabolite of codeine

morphine

19

major metabolite of heroin

6 monoacetylmorphine
morphine

20

hydrocodone

hydromorphone

21

oxycodone

oxymorphone

22

an assay in which oxycodone ahs 20% cross reactivity

Need to 5X more oxycodone to give a positive Opiate Screen r
• ~ 1500 ng/mL oxycodone to give a positive screening test
• when a 300 ng/mL cut‐off is used

23

when oxycodone has .4% reactivity

Need to 250X more oxycodone to give a positive Opiate Screen result than morphine
~ 75000 ng/mL oxycodone to give a positive screening test
• when a 300 ng/mL cut‐off is used

24

What antibiotics can produce positive results on opioid assays?

levofloxacin or ofloxacin

25

Amphetamine screening assays can detect:

amphetamine
methamphetamine
MDMA/MDA
ephedrine, pseudoephedrine, phenylpropaoloamine

26

What drugs can give a false positive on a amphetamine screening test?

aderrall- amphetamine (ADHD)
dexedrin (Narcolepsy/adhd) - d amphetamine
desoxyn (ADHD) - methampeht
Desprenyl (parkinsons) - selegiline
Gewodin (analgesic, antipyretic) - famprofazone

27

what are the chiral compounds of amphetamines? what is the difference between the two?

S - amphetamine = stimulate CNS
R- amphetamine = accat peripherally

illicit amphetamines are mixutres of S and R

28

What benzos have the most abuse potential?

ones w/ hte shortest half life/highest potency = alprazolam, traizolam

grestest lipophilia = diazepam

29

What is a benzo screening assay?

• Antibody directed against a single benzodiazepine.
• Therefore, detection of other benzodiazepines depend on antibody specificity.

30

What type of test has hte highest sensitivity for benzos?

LC/MS/MS assay is much more sensitive than the benzodiaz immunoassay

31

How are benzos metabolized?

chlordiazeproxide > demoxepam > nordiazepam

Diazepam --> nordiazepam

nordizaepam to oxazepam

(through oxidation/ glucuronidation)

32

What cut off has been recommended to use to monitor compliance w/ benzo therapy?

Using 200 ng/mL cut‐off, immunoassays only detected 21% of the specimens as positive in patients receiving clonazepam.

It has been suggested to use 40 ng/mL cut‐off for monitoring compliance with benzodiazepine therapy.

33

What cut off has been recommended to use to monitor compliance w/ benzo therapy?

Using 200 ng/mL cut‐off, immunoassays only detected 21% of the specimens as positive in patients receiving clonazepam.

It has been suggested to use 40 ng/mL cut‐off for monitoring compliance with benzodiazepine therapy.

34

Positive immunoassay should be considered presumptive until comfirmed by...

mass spec

35

What hsould be considered w/ a false positive result?

A false‐positive result can be caused by the apparent drug or by one of its metabolites. Many manufacturer‐based interference studies evaluate only the parent compound and therefore do not rule out the potential of a given drug to produce a false positive.

• We recommend that laboratory scientists facing discrepant drug‐ screening results review the clinical situation and prescribed medications, consider sending the sample for confirmation, contact the immunoassay manufacturer for additional data not available in the package insert, stay engaged with the medical team, and consider additional testing to determine the source of the false positive.