Toxicology

Question 1

What allows for longer detection times, urine or serum?

Answer 1

urine

Question 2

What is an immnoassay based screening assay?

Answer 2

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).

Question 3

What can be used for confirmation testing?

Answer 3

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

Question 4

What are characteristics of normal urine?

Answer 4

• 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)

Question 5

What are signs of phony urine samples?

Answer 5

• 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

Question 6

What are cannabinoids?

Answer 6

unique set of chemicals found in cannabis plant

most psychoactive chemical is delta 9 THC

Question 7

What does the UDS detect of cannabinoids?

Answer 7

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

Question 8

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

Answer 8

1 week

Question 9

long term use can produce positive results for up to…

Answer 9

46 days

Question 10

Is passive exposure of cannabis possible?

Answer 10

possible but unlikely

Question 11

How does an opiates screening assay work?

Answer 11

• 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

Question 12

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

Answer 12

efavirenz
PPIs
Hemp containing foods
eye drops (visine)

Question 13

what is the difference between an opiate vs opioid?

Answer 13

• 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

Question 14

opium

morphine codeine

Answer 14

from opium

Question 15

heroin, hydrocodone, hydromorphone, oxycodone

Answer 15

semisynthetic

Question 16

methadone, propoxyphene, merperidine, fentanyl

Answer 16

synthetic

Question 17

methadone, propoxyphene, merperidine, fentanyl

Answer 17

synthetic

Question 18

Major metabolite of codeine

Answer 18

morphine

Question 19

major metabolite of heroin

Answer 19

6 monoacetylmorphine

morphine

Question 20

hydrocodone

Answer 20

hydromorphone

Question 21

oxycodone

Answer 21

oxymorphone

Question 22

an assay in which oxycodone ahs 20% cross reactivity

Answer 22

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

Question 23

when oxycodone has .4% reactivity

Answer 23

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

Question 24

What antibiotics can produce positive results on opioid assays?

Answer 24

levofloxacin or ofloxacin

Question 25

Amphetamine screening assays can detect:

Answer 25

amphetamine
methamphetamine
MDMA/MDA
ephedrine, pseudoephedrine, phenylpropaoloamine

Question 26

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

Answer 26

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

Question 27

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

Answer 27

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

illicit amphetamines are mixutres of S and R

Question 28

What benzos have the most abuse potential?

Answer 28

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

grestest lipophilia = diazepam

Question 29

What is a benzo screening assay?

Answer 29

• Antibody directed against a single benzodiazepine.

* Therefore, detection of other benzodiazepines depend on antibody specificity.

Question 30

What type of test has hte highest sensitivity for benzos?

Answer 30

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

Question 31

How are benzos metabolized?

Answer 31

chlordiazeproxide > demoxepam > nordiazepam

Diazepam –> nordiazepam

nordizaepam to oxazepam

(through oxidation/ glucuronidation)

Question 32

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

Answer 32

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.

Question 33

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

Answer 33

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.

Question 34

Positive immunoassay should be considered presumptive until comfirmed by…

Answer 34

mass spec

Question 35

What hsould be considered w/ a false positive result?

Answer 35

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.