drug testing

medical drug testing purposes

monitor pt’s progress

determine presence of drugs before treatment

is simple and relatively inexpensive

not likely to be used as evidence in court

legal drug testing purposes

determines use of drugs prior to accident or crime

**requires confirmatory test in addition to a urine test (GC/MS)

medical drug testing purposes

monitor pt’s progress

determine presence of drugs before treatment

is simple and relatively inexpensive

not likely to be used as evidence in court

legal drug testing purposes

determines use of drugs prior to accident or crime

**requires confirmatory test in addition to a urine test (GC/MS)

urine drug screens general characteristics

generally the specimen of choice

non-invasive, many metabolites/drugs excreted this way, stable when frozen, relatively clean matrix

reported as either indicative/presumptive or negative

can be adulterated, or some people can have a shy bladder

cut-off values

determined by SAMSHA for the following drugs:

• amphetamines

• cocaine metabolites

• marijuana metabolites

• opiate metabolites

• phencyclidine

SAMSHA

substance abuse and mental health services administration

specifies the cut-off values for the 5 drug categories

medicolegal drug testing purposes

used in employer drug abuse programs to prevent drug-related accidents/crimes

used to identify and treat employees with drug abuse problems

requires a two-tier test (urine test and a more specific, sensitive test)

true or false: there is more stringent testing required for legal/medicolegal drug testing than medical drug testing

true

EMIT

most widely used form of drug test

inexpensive, initial screen

easiest to beat due to lack of specificity

if +, confirm with GC/MS

radioimmunoassay (RIA)

drug test used by the military that is more specific/expensive than the EMIT, but still beatable

if +, requires a confirmation test

immunoassays

type of drug test that is easily automated with fast results done in small labs/clinics

currently the only practical way to deal with large sample numbers

4 general considerations for drug testing

cross-reactivity

specificity

cut-off level

adulterants

GC/MS

most sophisticated and expensive form of drug test

highly specific, used for confirmation

sample types that can be tested

breath (alcohol)

urine

blood

hair

saliva

blind urine sample procedure

donor’s sample is submitted along with a negative or spiked sample to determine if it is positive

split urine sample procedure

donor’s sample is split into two bottles collected from the same void by the donor

primary seal

lid/cap of urine specimen bottle with a tamper proof seal

secondary seal

leak-proof plastic bag that the urine specimen bottle is placed

true or false: tamper proof seals are not required for the shipping container for urine samples

false

chain of custody of urine samples

procedure used to determine the handling of a specimen from time of donation to when it is destroyed

MRO - licensed physician who interprets the lab results

fatal flaw - error that raises doubt about a specimen’s integrity or the information concerning the specimen

true or false: a negative urine screen means that a drug was not present or taken

false

true or false: a negative urine screen means that a drug was not detected

true

how long can amphetamines be detected in urine?

2-5 days, up to 2 weeks with heavy use

how long can cocaine metabolites be detected in urine?

2 weeks, up to 6 weeks with heavy use

how long can LSD be detected in urine?

1-2 days

how long can marijuana metabolites be detected in urine?

7-10 days, up to 1 month with heavy use

how long can opioids be detected in urine?

2-3 days

how long can methadone be detected in urine?

3-14 days

how long can PCP be detected in urine?

2-10 days

dilution method

way to beat an initial screening drug test

consume large quantities of fluids

avoiding morning urines for testing

diuretics

taking vitamin B2 to add yellow color to urine

substitution of clean urine

way to beat an initial screening drug test

can include doping or ordering powdered urine from an internet supplier

adulterants

way to beat an initial screening drug test

can include bleach, detergents, or urinaid

*urinaid does not work on RIA tests

other ways to beat initial screening drug tests

niacin + golden seal

drinking vinegar or visine

interfering with the chain of custody

hair analysis drug test

non-invasive test that can evaluate drug use for roughly 90 days (1.5in of hair in 90 days)

can’t determine recent use (7-10 days prior to test) or low-dosage use

factors affecting drug concentrations in hair

exogenous exposure can mimic drug use

physiochemical factors (drug concentration, time of exposure, pH)

ethnic differences

cosmetic treatments/hygeine

important toxicological tests

includes APAP, digoxin, CO poisoning, lithium, and salicylate

APAP toxicity

serum concentration must be taken at least 4 hours after acute ingestion to assess whether the pt is at risk for APAP toxicity

Rumak-Matthew Nomogram/APAP nomogram: semi-log plot of serum APAP vs time

hospital alcohol testing

alcohol dehydrogenase based assay/indirect assay

usually measuring serum or plasma concentration rather than whole blood concentration (ethanol distributes in water content → greater concentration in serum than whole blood)

is subject to interferences (other alcohols, lactate)

whole blood alcohol concentration = serum alcohol / 1.14

interpretation of drug tests

indicates that a drug has been ingested, but not able to determine when or the level of impairment

requires a confirmation test - screening test not sufficient for determining exposure