Toxicology and Drugs

Toxicology and Drugs

Basic Definitions

Toxicology:

The study of toxins and drugs in the body.

Toxin:

Any material exerting a life threatening effect upon a living organism.

Toxic materials exist in many forms (gaseous, liquid, solid, animal, mineral, and vegetable), and may be ingested, inhaled, or absorbed through the skin.

Toxins work in minute quantities or low levels, requiring sensitive analytical instruments for detection.

Toxic substances may

-Contribute to death

-Be cause of death

-Cause impairment

-Explain behavior

Poisons are a subgroup of toxins.

Poisons generally enter the body in a single massive dose, or accumulate to a massive dose over time.

Types of Toxicology

Environmental: Air, Water, Soil

Consumer: Food, Cosmetics

Medical, Clinical, Forensic

Forensic Toxicology

Detects and Identifies

-Presence of drugs & poisons

-Body Fluids

-Examines tissues & organs

Work in crime labs & medical examiners’ office

Forensic Toxicology

May also work in hospital labs to identify drug overdoses or monitor the intake of drugs

Major job is measurement of alcohol in the body (motor vehicle accidents)

Aspects of Toxicology

Dosage

-The chemical or physical formof the substance

-The mode of entry into the body

Toxin/Poison

-Influenced by body weight & the physiological including age & sex

-The mode of entry into the body

Toxin/Poison

-The time period of exposure

-The presence of other chemicals in the body

LD50

- Refers to the dose of a substance that kills half the test population, usually within four hours

- Expressed in milligrams of substance per kilogram of body weight

Toxicity Classes

Federal Regulatory Agencies

Food & Drug Administration (FDA)

Environmental Protection Agency (EPA)

Consumer Product Safety Commission

Department of Transportation (DOT)

Occupational Safety & Health Administration (OSHA)

Poisons

Critical Information on Poisons

Form

Common Color

Characteristic Odor

Solubility

Taste

Common Sources

Lethal Dose

Mechanism

Possible Methods of Administration

Time Interval of Onset of Symptoms

Symptoms resulting from an acute exposure

Symptoms resulting from chronic exposure

Disease states mimicked by poisoning

Notes relating to victim

Specimens from victim

Analytical detection methods

Known toxic levels

Notes pertinent to analysis of poison

List of cases in which poison was used

Proving a Poison case

Prove a crime was committed

Motive & Intent

Access to poison & victim

Death was caused by poison

Death was a homicide

Forensic autopsy

Look for

-Irritated tissues

-Characteristic odors

-Mees lines: single transverse white bands on nails

Order Toxicological Screens:

–Postmortem concentrations should be done at the scene for comparison

–No realistic calculation of dose can be made from a single measurement

Specimens Taken for Analysis

-Liver, Kidney, Brain tissue

-Blood & Urine

-Hair & Nails

-Bile & Gastric Contents

-Vitreous Humor of Eye

Toxicology of ethyl Alcohol

Most abused drug

40% of traffic death are alcohol related

Affects the central nervous system

Acts as a depressant

Appears in the blood within minutes

Full absorption occurs in 30-90 minutes

Rate of Absorption Depends on

-Alcohol content

-Time taken to consume the drink

-Amount consumed

-Food present in stomach

-Physiology of the consumer

Alcohol Levels

-Elimination of alcohol throughout the body

-Detoxification occurs in the liver (90%)

-Excretion occurs unchanged in breath, urine, & perspiration (5%)

Blood Alcohol Content (BAC)

-Expressed as weight per volume of blood

-Influenced by:

Body weight, Alcohol content, number of beverages, time between

consumption

-Rate of elimination from the bloodstream is approximately 0.15% per hour

Alcohol and the Law

In 1972 legal limit made 0.08% (w/v)

In 1973 “implied consent” adopted by all states (drivers on a public highway will submit for a test for alcohol intoxication)

Preliminary Field Tests

-Used to determine the degree of a suspect’s physical impairment & if other tests are justified

Psychophysical Tests

-Three types

1. Horizontal Gaze Nystagmus

-Follow a pen or flashlight, tracking left to right with one’s eye

-Wavering at 45 degrees indicates0.10% BAC

2. Divided Attention Tests

-Comprehension of two instructions

-Examples

-Nine Step Walk & Turn (WAT)

-One Leg Stand (OLS)

Breathalyzer

-Collects and measures alcoholcontent in alveolar breath (deep

lung breath)

-Need 1.5 L of breath

-Chemical ones phased out in 1970s

-Today computerized using infrared light absorption

Drugs

Drug:

-Natural or synthetic

-Affect psychology or physiology

-Most produced legitimately for Rx

-If obtained by illegal means = “illicit drug” or “drugs of abuse”

-If taken in excess causing illness ordeath = poison

Drug types

Most drugs fit into one or more of the following categories

-Stimulants

-Narcotics

-Depressants

-Hallucinogens

Stimulants

-Speed up the CNS (amphetamines)

Narcotics

-Induce a state of sluggishness

-Most derived from the poppy plant

(codeine, heroin. morphine, oxycontin)

Drug types

Depressants

-Slow down the CNS (alcohol, inhalants)

Hallucinogens

-Cause marked alterations in thought process, perceptions, & mood

(LSD, PCP, marijuana)

Controlled substance act

Controlled Substance Act (1970)

-Drugs restricted by law

-Lists illegal drugs, their category

and their penalty for possession, sale or use.

-Five schedules based on potentialfor abuse & dependence & medical

use

Schedule I

-High potential for abuse

-No accepted medical use

-Lack of accepted safety for useunder medical supervision

-heroin, LSD, ecstasy (MDMA), marijuana

Controlled substance act

Schedule II

-High potential for abuse

-Currently accepted medical usewith severe restrictions

-Abuse may lead to severepsychological or physicaldependence

-cocaine, morphine, amphetamines, Ritalin, PCP, opium

Schedule III

-Lower potential for abuse than I or II

-Currently accepted medical use

-Abuse may lead to moderatepsychological or physicaldependence

-intermediate acting barbiturates, steroids, ketamine

Schedule VI

-Lower potential for abuse relative to drugs in III

-Currently accepted medical use

-Abuse may lead to limited psychological or physicaldependence relative to drugs in III

-other stimulants & depressants, valium, Darvon, librium, phenobarbital

Schedule V

-Lower potential for abuse relative to drugs in VI

-Currently accepted medical use

-Abuse may lead to limited psychological or physicaldependence relative to drugs in IV

-codeine found in cough medicine

Drug Identification

PDR (Physician's Desk Reference)

-Identifies manufactured pills, tablets, &capsules

-Gives a picture of the drug, whether OTC, prescription, or controlled substance

-Updated yearly

Presumptive or Screening Tests

-Scott Test

Turns blue in the presence of cocaine

-Marquis Test

Turns purple in the presence of heroin,morphine, & most opium derivatives

Turns orange-brown in the presence ofamphetamines

Presumptive or Screening Tests

-Van Urk

Turns blue purple in the presence of LSD

-Dillie-Koppanyl

Turns violet-blue in the presence ofbarbiturates

Drug Identification

Presumptive or Screening Tests

-Duquenois-Levine

Turns a purple in the presence of marijuana

Microcrystalline Test

-A reagent is added that produces acrystalline precipitate which is unique fora certain drug

-More specific than color tests

Confirmatory Test

-Spectrophotometry

Ultraviolet (UV)

Visible

Infrared (IR)

Mass Spectrometry

Drug Identification

Chromatography

-Separates components of a mixture

-Consists of 2 phases mobile & stationary

-Mobile: liquid solvent

-Stationary: Depends on type of

chromatography. Can be paper, glass,

silica

Drug Identification

Chromatography

-Types

Thin Layer (TLC)

Gas (GC)

Liquid (LC)

High Pressure Liquid (HPLC)

Paper

Column