Drugs and Toxicology

Introduction Forensic toxicology helps determine (a) the cause- and-effect relationships between exposure to a drug or other substance and (b) the toxic or lethal effects from that exposure. People can be exposed to toxic substances: intentionally—by treating illness or relieving pain accidentally—by harmful combinations or overdoses deliberately—by harming or killing others or by committing suicide

Poison—Murder, Accidental Overdoses, and Drug Offences Less than ½ of 1% of all homicides results from poisoning. Accidental drug overdoses are more common. More than 50% of the federal prison population and about 20% of the population in state prisons consist of drug offenders.

Drug – a natural or synthetic substance that is used to produce physiological or psychological effects in humans or other higher-order animals.

I. Drug Dependence Psychological dependence – the conditioned use of a drug caused by underlying emotional needs. Physical dependence – physiological need for a drug that has been brought about by its regular use. Dependence is characterized by withdrawal sickness when administration of the drug is abruptly stopped.

II. Narcotic Drugs Narcotic – analgesic or pain-killing substance that depresses vital body functions such as blood pressure, pulse rate, and breathing rate. The regular administration of narcotics will produce physical dependence. Analgesic – a drug or substance that lessens or eliminates pain.

The source of most analgesic narcotics is opium. Opium compounds include morphine, heroin, and codeine. Non-opium narcotics are often called “opiates” due to their similar physiological effects on the body. The most well known of these is Methadone which is used in heroin addiction treatment programs.

III. Hallucinogens Hallucinogens – a substance that induces changes in mood, attitude, thought, or perception. The most common hallucinogen is Marijuana. Use of marijuana and its related products date back almost three thousand years.

Marijuana refers to a preparation derived from the plant Cannabis. Most botanists believe there is only one species of the plant, Cannabis sativa L. The marijuana normally consists of crushed leaves mixed in varying proportions with the plant’s flower, stem and seed. The plant secretes a sticky resin that is known as hashish.

Marijuana is a weed that grows wild under most climatic conditions. The plant grows to a height of 5 to 15 feet and is characterized by an odd number of leaflets on each leaf. Normally, each leaf contains five to nine leaflets, all having serrated or saw-tooth edges.

The chemical substance responsible for the hallucinogenic properties of marijuana is tetrahydrocannabinol or THC. The THC content of Cannabis varies in the different parts of the plant. The resin is the strongest followed by the flowers and leaves. Very little THC is found in the stem, roots, or seeds.

Other common hallucinogens include lysergic acid diethylamide (LSD), mescaline, and phencyclidine (PCP). PCP is often mixed with other drugs, such as LSD or amphetamine, and is sold as a powder (“Angel Dust”), capsule, or tablet, or as a liquid sprayed on plant leaves.

Methylenedioxymethamphetamine, also know as MDMA or Ecstasy, has gained worldwide attention as the latest “designer drug” Ecstasy is a synthetic, mind- altering drug that exhibits many hallucinogenic and amphetamine-like effects.

IV. Depressants Alcohol (Ethyl alcohol) is a drug! Depressant - a substance used to depress the functions of the central nervous system. Depressants calm irritability and anxiety and may induce sleep. Alcohol is the most widely used and abused drug (SURPRISE!)

Behavioral patterns are varied and depend on social setting, amount consumed, and personal expectation of the individual with regard to alcohol. Low doses tend to inhibit the mental processes of judgment, memory, and concentration. Alcohol has been found to reduce coordination, inhibit thought processes and speech patterns, and slow down reaction times.

Higher doses of alcohol may cause the user to become highly irritable and emotional. Overdoses may cause unconsciousness or coma that may depress circulatory and respiratory functions.

Barbituates are commonly referred to as “downers” because they relax, reacte a feeling of well-being, and produce sleep. Derivatives of barbituric acid. 25 varieties commonly used in medicine in the U.S. Five most common are amobarbital, secobarbital, phenobarbital, pentobarbital, and butabarbital.

Slang terms usually indicate color - “yellow jackets” ”blue devils” “reds” Normally taken orally mg per dose. Some act slower than others. Normally not physically addictive unless intake exceeds recommended amount. Withdrawal must be supervised to avoid death.

Quaalude - (methaqualone) is a nonbarbituate depressant that is a powerful sedative and muscle relaxant that possesses properties of barbituates. Tranquilizers - differ from barbituates in that they act on the central nervous system. They does not impair higher level thinking or induce sleep

Mild tranquilizers include meprobamate(Miltown), chlordiazepoxide (Librium), and diazepam (Valium) Tranquilizers do produce physical and psychological dependence with repeated and high levels of use. Glue Sniffing - includes the sniffing of materials containing solvents.

Volatile or gaseous substances are primarily central nervous system depressants. Toluene seems to be most popular but others include naphtha, methyl ethyl ketone, gasoline, and tricholoethylene. Immediate effects - feeling of exhilaration and euphoria combined with slurred speech, impaired judgment, and double vision.

Creates psychological dependence but not physical dependence. Exposure to these chemicals can be damaging to the liver, heart, and brain.

V. Stimulants Stimulant - a substance taken to increase alertness or activity. Amphetamines - A group of synthetic drugs that stimulate the central nervous system. Commonly referred to as “uppers” or “speed”.

Therapeutic doses of 5-20 mg per day provide feeling of well-being and increased alertness. Most common abuse is methamphetamine. Creates a “rush” followed by intense pleasure. Smokable form of methamphetamine is “ice”. Effects are similar to crack cocaine but last longer.

Cocaine - powerful stimulant to the central nervous system extracted from the leaves of the Erythroxylon coca plant found in South America and Asia. Effects include increased alertness and vigor accompanied by the suppression of hunger, fatigue, and boredom. Most commonly sniffed or “snorted”

Popular form is “crack”. Made by mixing ordinary cocaine with baking soda and water into a solution that is heated in a pot. The material is then dried and broken into chunks. Users then smoke it in a glass pipe. Crack, like cocaine, produces a feeling of euphoria by stimulating the pleasure center in the base of the brain.

VI. Anabolic Steroids Anabolic steroids - steroids that promote muscle growth. They are synthetic compounds chemically related to the male sex hormone testosterone. Two effects - secondary male characteristics (androgen effects) and accelerated muscle growth.

VII. Drug-Control Laws Medical and legal classifications often differ. U.S. federal law - Controlled Substances Act. Many state laws based on this. Controlled Substances Act - five schedules of classification for controlled dangerous substances.

VIII. Toxicology of Alcohol Forensic toxicology - the detection and isolation of drugs in the body for the express purpose of determining their influence on human behavior. Alcohol or ethyl alcohol - a colorless liquid normally diluted with water and consumed as a beverage.

The Fate of Alcohol in the Body Absorption - passage of alcohol across the wall of the stomach and small intestine into the blood stream. Absorption is variable and can be affected by factors such as body weight, food present, alcohol content of the drink, and time taken to consume. Alcohol is a depressant with its principal effect on the central nervous system, particularly the brain.

Evidence supports the idea that because blood containing alcohol is carried through the body tissues including the brain, the blood alcohol concentration is directly proportional to the concentration of alcohol in the brain.

Bacterial Toxins Tetanus Lockjaw, as it is sometimes called, is produced by the Clostridium tetani bacteria. Its poison can cause violent muscle spasms. Botulism Produced by the bacteria Clostridium botulinum, botulism paralyzes muscles. It causes irreversible damage to nerve endings. Very small amounts are extremely deadly. Botulism is the most poisonous biological substance.

Pesticides and Heavy Metals Pesticides mostly are used to protect plants or food crops. Metal compounds are very poisonous.

Metal compounds can damage many organs in the body.

Bioterrorism Agents Ricin is a poisonous protein in the castor bean. is lethal in extremely small amounts. can enter the body in various ways: – inhaled as a mist or a powder. – ingested as food or drink. – injected into the body. can cause death within a few hours.

Anthrax is caused by the bacteria Bacillus anthracis, which forms spores. can be spread to humans from infected animals. can enter the human body through: – inhalation; causing breathing problems that usually result in death. – ingestion; becoming fatal in 25% to 60% of cases. – absorption via the skin; leading to death in about 20% of untreated cases.