Chapter 5: Drug Screens

How drug tests are beat

*Note: applies to initial drug screenings 1. Dilution method: consume large quantities of fluids, avoid morning urine for testing, diuretics, take vitamin B2 to add yellow color to urine 2. Substitution of clean urine: doping, powdered urine 3. Adulterants: bleach, detergents, urinaid (does not work on RIA tests) 4. Niacin and golden seal 5. Drinking vinegar or visine 6. Interference w/ chain of custody

Important toxicological tests

Acetaminophen Carboxyhemoglobin (CO poisoning) Digoxin Lithium Salicylate

Urine detection times

Amphetamine: 2-5 days, 2 weeks w/ chronic use Cocaine: 2 weeks, 6 weeks w/ chronic use LSD: 1-2 days Marijuana: 7-10 days, 1 month w/ chronic use Opioids: 2-3 days Methadone: 3-14 days PCP: 2-10 days

Urine testing procedures

Blind sample: negative or spiked sample submitted with donor's sample Split sample: Single specimen split into two separate specimen bottles Never collected from two different voids by donor Bottle A- first specimen (30mL) Bottle B- second specimen (15mL)

What can be tested?

Breath (alcohol) Urine Blood Hair Saliva Level of impairment

Drug testing- general considerations

Cross-reactivity Specificity Cut-off level Adulterants

Legal drug testing

Determine use of drugs prior to accident or crime Requires confirmatory test

Negative urine screen

Does not mean the drug was not present or not taken IT MEANS THE DRUG WAS NOT DETECTED Drugs not routinely detected: androgenic steroids, GHB (rape drug), anticoagulants, meperidine (opiate)

Types of drug tests

EMIT (screening test) RIA (screening test) TLC (thin layer chromatography) GC/MS (confirmation test)

Immunoassays

Easily automated Currently the only practical tool for dealing with large sample numbers Fast results Can be run by small labs, clinics

Factors affecting drug concentrations in hair

Exogenous exposure can mimic drug use Physiochemical factors: drug concentration, time of exposure, pH, cations (sodium) Ethnic differences Cosmetic treatments and hygiene

Type of testing

Hospital alcohol testing: Measures alcohol dehydrogenase based assay Usually is measuring serum or plasma rather than whole blood Subject to interferences (other alcohols, lactate)

Interpretation of drug tests

Indicates that a drug has been ingested Unlikely to be able to relate to level of impairment Usually not able to determine when most drugs were ingested Requires confirmation test- screening test not sufficient for determining exposure

Purpose of Drug Testing

Medical Legal Medicolegal

Medical drug testing

Monitors patients' progress Determine presence of drugs before treatments Simple, less expensive methods Unlikely to be used as evidence in court

GC/MS

More sophisticated Very specific Used as confirmation test

RIA (radioimmunoassay)

More specific and expensive than EMIT Used by military Specificity is better than EMIT but still can be "beat" Also requires confirmation test

Legal and medicolegal drug testing

More stringent testing required Must withstand technical criticism Two tiered-testing program: urine screening test (there may be drug there) --> more specific, sensitive test (GC/MS)(drug is present at this amount) Testimony upheld based on positive results obtained on two separate tests using two chemical methods

EMIT

Most widely used test due to lost cost Designed as an initial screen If test is positive, confirm with GC/MS Easiest test to beat due to lack of specificity

Hair analysis

Non-invasive Requires ~60 hairs (thickness of pencil) Can evaluate drug use for roughly 90 days More expensive Cannot determine recent use Not sensitive for low dosage use

Urine collection

Observation Color Temperature Volume

Home drug testing

Parents Alert, Inc.- founded by mother of 2 teenagers in Smyrna, GA 1995 Tests for: alcohol, marijuana, cocaine, amphetamine, PCP, LSD Ethical/practical issues: usefulness of test, ability to obtain sample, privacy rights

Urine testing procedures- cautions

Primary seal: lid/cap of specimen bottle with tamper proof seal Secondary seal: leak-proof plastic bag in which specimen bottle is placed Shipping container: must be sealed and have tamper proof seal

Chain of custody

Procedure used to document the handling of specimen from time of donation until it is destroyed Fatal flaw: error that raises doubt about the integrity of a specimen or the information concerning the specimen Medical review officer (MRO): licensed physician who interprets the lab results

Acetaminophen toxicity

Serum concentration obtained at least 4 hrs after acute ingestion can be used to assess whether patient is at risk for APAP hepatotoxcity Rumak-Matthew Nomogram: APAP monogram, semi-log plot of serum APAP vs. time

Cut-off values

Substance Abuse and Mental Health Services Administration (SAMSHA) specifies cut-off values SAMSHA requires 5 drug categories to be routinely included in urine screens: 1. Amphetamines [meth, MDMA/ecstasy] 2. Cocaine 3. Marijuana 4. Opiate- morphine, codeine, NOT fentanyl, methadone 5. Phencyclidine Cut-off values may be lowered in some cases

Urine drug screens

Urine is specimen of choice because: Collection is non-invasive Most drugs/metabolites are excreted and concentrated in urine Drugs/metabolites are stable in frozen urine Usually a relatively clean matrix Based on cut-offs, urine screen is reported as indicative/presumptive or negative

Characteristics of specimens

Urine: window of detection typically 1-5 days; can be adulterated, shy bladder Hair: longest window of detection, usually 90 days based on collection of 1.5in of hair; non-invasive, expensive, will NOT detect recent use (7-10 days prior to use) Saliva: reflects recent use (10-24hrs), noninvasive, drugs and metabolites not not remain in sample long, limited value Sweat: limited value

Medicolegal drug testing

Used in employer drug abuse programs to prevent drug-related accidents or crime Used to identify and treat employees with drug abuse problems

What was tested?

Whole blood vs. serum: Serum contains a greater water content than whole blood Since ethanol distributes in water content, greater ethanol concentration in serum than whole blood Whole blood alcohol concentration= alcohol concentration/1.14