Drugs, Poisons and Forensic Toxicology

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Drugs, Poisons and Forensic Toxicology

• Read intro to ch.9 on Anna Nicole Smiths Death

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History of Toxicology

• Paracelsus (1493-1541)
• Devised the dose-response relationship between
  therapeutic and toxic levels of drugs
• Orfila (1787-1853)
• Contributed to the development of forensic
  toxicology and the study of poisoning in criminal
  actions

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3 main categories of work for a forensic
toxicologist

• identification of drugs such as heroin, cocaine,
  cannabis
• detection of drugs and poisons in body fluids,
  tissues, and organs
• measuring of alcohol in blood or urine samples

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Toxic substances are classified by how people are
exposed to them

• Intentionally as in drugs taken to treat an
  illness or relieve pain
• Accidentally ingested/exposed, as in
  unintentional overdose due to harmful
  combinations of meds.
• Deliberately as in suicide or exposure intended
  to harm or kill others

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Anions

• Anions are negatively charged ions
• The most important of these is cyanide (CN-)
• Cyanide blocks proteins in the mitochondria
  affecting metabolism lactic acid builds up
  causing lactic acidosis
• The brain's high metabolic rate accounts for its
  disproportionate vulnerability to cyanide.
• No matter how cyanide gets into your body, it
  works the same way. In addition to inhaling
  cyanide gas, it can be swallowed or absorbed
  through your skin.
• Symptoms
• Rapid (fast) breathing.
• Dizziness.
• Weakness.
• Headache.
• Nausea and vomiting.
• Rapid heartbeat.

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Corrosive Poisons

• Cause destruction of body tissues upon contact
• Severity depends on concentration and length of
  contact time
• If ingested, corrodes digestive tissues and may
  perforate the gut
• Less commonly used as poisons since they are easy
  to detect
• Examples HCl, HNO3, H2SO4 and KOH and NaOH

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Gaseous and Volatile Poisons

• These are substances that turn into the gas form
  easily at room temperature to produce toxic
  vapors
• Most common of these is carbon monoxide
  generally formed from the burning of fossil fuels
• CO binds more strongly to hemoglobin than O2 does
• Victims therefore asphyxiate
• Deaths may be accidental (e.g. faulty gas
  furnaces or smoke inhalation in fires) or
  intentional (e.g. suicides from gas exhaust)
• In accidental deaths, victims are unaware they
  are being poisoned since CO is colorless and
  odorless
• Victims become sleepy due to lack of O2 to the
  brain and lose consciousness
• When CO binds to hemoglobin, it turns it cherry
  red so bright red skin is a sign of CO poisoning

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Metalloid Poisons

• Metalloids (elements which are intermediates of
  metals and nonmetals in terms of malleability,
  ductility, conductivity and luster) include
  arsenic (As) and antimony (Sb)
• Interferes with cellular respiration
• Once a popular poison because it could be added
  to food and resulted in symptoms similar to
  dysentery and cholera now is less common since
  traces remain in the hair, nails and bones well
  after death
• Napoleon was thought to be poisoned with arsenic
  by his British captors later found to be
  baseless claims
• Accidental ingestion still happens since arsenic
  is found in weedkillers and insecticides

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Metal Poisons

• Metals such as mercury (Hg), lead (Pb), lithium
  (Li) and thallium (Tl) are also toxic some,
  like mercury, in fairly low doses
• They create symptoms similar to metalloid poisons
• Sometimes ingested without knowing it in low
  doses which may accumulate over time (e.g.
  mercury dumped into water bodies accumulates in
  fish which we eat)

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Pesticides

• Pesticides are substances used to kill pest
  organisms (fungicides, herbicides, insecticides)
• How they act on humans varies because of their
  differing target organisms (e.g. a herbicide
  works differently than an insecticide) but may
  cause vomiting, paralysis and/or convulsions
• Many insect and mammalian poisons are
  particularly dangerous because they are not host
  specific and are designed specifically to kill a
  wide range of organisms
• Because of their widespread agricultural use as
  well as availability to consumers, accidental
  exposure by direct exposure to the pesticide is
  not uncommon
• Pesticides have also been used as poisons
  deliberately or as a means of suicide

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Toxins

• Toxins are poisonous substances produced by an
  organism (plant, animal, fungus or microorganism)
• Natural toxins are a very diverse group both in
  terms of how they work and in their chemistry
• May be medicinal, toxic or even recreational
• One important group is the alkaloids (containing
  nitrogen bases)

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A few alkaloid examples

• Atropine (deadly nightshade)
• Atropine blocks nerve cell transmission in the
  parasympathetic nervous system (the PSN slows the
  heartbeat and speeds up digestion)
• Symptoms, therefore, include increased heart
  rate, dilated pupils, and difficulty breathing

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A few alkaloid examples

• Strychnine (poison berry)
• Strychnine prevents the proper operation of the
  chemical that controls nerve signals to the
  muscles
• The chemical controlling nerve signals works like
  the bodys off switch for muscles
• When this off switch does not work correctly,
  muscles throughout the body have severe, painful
  spasms. Even though the persons consciousness or
  thinking are not affected at first (except that
  the person is very excitable and in pain),
  eventually the muscles tire and the person cant
  breathe.
• This is allegedly one of the most painful deaths
  imaginable as every muscle in your body contracts

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Brown Recluse-venom causes death of soft tissue
that may take months to heal and can leave large,
deep scars
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Brown recluse bite
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Controlled Substances

• A drug is a natural or synthetic substance used
  to produce a psychological or physiological
  effect
• Today, approximately 23 million people in the US
  are illicit drug users
• More than 75 of the evidence evaluated by crime
  labs are drug related

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Drug Dependence

• Drug dependence varies based on the nature of the
  drug, the route of administration, the dose, the
  frequency of use and the individuals rate of
  metabolism
• Psychological needs arise from numerous personal
  social factors that stem from the individuals
  desire to create a sense of well-being to
  escape from reality.
• Certain drugs, when taken in sufficient dose and
  frequency, are capable of producing physiological
  changes that encourage their continued use
  (withdrawal sickness body chills, vomiting,
  stomach cramps, convulsions, insomnia, pain
  hallucinations)

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Categories of Drugs Based on Their Effects on the
Central Nervous System

• Stimulants stimulates brain activity
  (amphetamines, cocaine, methamphetamines)
• Depressants Inhibits brain activity (Alcohol,
  barbiturates, heroin, GHB, Rohypnol, huffing)
• Hallucinogens alterations in perception and mood
  without affecting brain activity (Ecstasy, LSD,
  PCP, cannabis)
• Narcotics reduce pain by suppressing central
  nervous system (opiates, heroin, codeine,
  methadone, oxycodone)

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Stimulants Amphetamine

• AMPHETAMINES-synthetic drugs that stimulate
  nervous system- uppers or speed
• once stimulant wears off, depression may set in.
• Were once used in diet pills since it suppresses
  appetites also increases heart rate, blood
  pressure and temperature

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Cocaine

• Derived from the coca plant grown in the Andes
  mountains of South America and tropical Asia.
• Cocaine has had historical medical use as local
  painkiller or anesthetic
• Cocaine is a powerfully addictive stimulant drug.
  The powdered, hydrochloride salt form of cocaine
  can be snorted or dissolved in water and
  injected.
• Crack is freebase cocaine and is smoked inhaling
  the vapor gets a larger dose of the drug to the
  bran in less than 15 sec.

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Crack cocaine

• This form of cocaine comes in a rock crystal that
  can be heated and its vapors smoked. The term
  "crack" refers to the crackling sound heard when
  it is heated.
• The feeling of euphoria that crack provides fades
  quickly and leaves the user feeling anxious,
  depressed and pleasureless.
• Only a small percentage of crack abusers will
  ever be cured of this drug habit
• Cocaine-related deaths result of cardiac related
  seizures followed by respiratory arrest.

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Methamphetamine

• Produces intense rush or flash followed by
  pleasure.
• Smokeable form of Meth is Ice
• Repeated use of amphetamines leads to strong
  psychological dependency
• Methamphetamine is also produced in clandestine
  drug labs (a big problem in the Pacific
  northwest)
• Chronic users exhibit violent destructive
  behavior and acute psychosis, similar to paranoid
  schizophrenia.

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DEPRESSANTS- slow down the central nervous system

• ALCOHOL tends to inhibit the mental processes of
  judgment, memory, and concentration in low
  doses.
• In 2000, the federal government established 0.08
  as the legal blood-alcohol limit. France,
  Germany, Ireland, Australia and Japan set 0.05
  Sweden is 0.02.
• A person with 0.08 level is four times more
  likely to become involved in an car accident as a
  sober person at 0.15 you are 25 times more
  likely.

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Hallucinogens Marijuana

• MARIJUANA has been used legally and illegally for
  3000 yrs- references to it in medical and
  pharmacological uses.
• Was used for
• painkiller,
• mild sedative,
• weakness,
• malaria,
• constipation,
• gout, etc.
• 1964- scientists isolated chemical substance
  largely responsible for the hallucinogenic
  properties of marijuana tetra hydro cannabinol
  (THC)
• THC content varies in parts of the plant- resin,
  flowers, leaves.
• Marijuana has been authorized for use in medical
  profession
• Reduction of excessive eye pressure in glaucoma
• Lessoning of nausea by anti-cancer drugs.
• Muscle relaxer and to increase appetite

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LSD PCP

• Lysergic acid diethylamide, a synthesized form of
  lysergic acid
• Substance derived from ergot
• Drug is very potent, as little as 25 micrograms
  is enough to start visual hallucination
• Physical dependence does not develop with
  continued use, but the user may be prone to
  flashbacks and psychotic reactions even after us
  is discontinued.
• PCP is often mixed with other drugs, LSD or
  amphetemines.
• It initially causes the user to feel stronger,
  invulnerable and detached from reality. Users
  soon become unresponsive, confused and agitated.
• Long-term daily use can cause severe depression,
  tendencies toward violence, and suicide.

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Narcotics Morphine/Heroin

• Morphine is extracted from opium (opiates)
• Has medicinal uses as a pain reliever
  (analgesic). Regular use leads to physical
  dependence.
• Most addicts prefer a derivative of morphine
  heroin.
• Heroin has high solubility rate in water- easy
  street preparation for intravenous administration
  for injection.
• Process is accelerated by heating in spoon, drawn
  into a syringe or eyedropper for injection.
• CODEINE is also present in opium- prepared
  synthetically from morphine- used as cough
  suppressant.
• METHADONE- synthetic opiate- used for treatment
  of heroin addicts- similar drug but less side
  effects in withdrawal.
• OXYCONTIN-synthetic opiate-used as a painkiller.
  Doctors write close to 7 million prescriptions
  for oxycontin annually it is estimated that
  close to ¼ million people abuse this drug.

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Heroin

• Once heroin is produced it may reduced to powder
  form
• Heroin is highly soluble in water
• This makes street preparation for intravenous
  administration rather simple
• In the 1960s and 70s, the average bag of heroin
  sold contained 15-20 heroin. Currently the
  average purity is 35.

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Drug Identification

• So far we have only looked at a small number of
  drugs there are many more, often mixtures of
  different drugs a forensic chemist may analyze
• These contain active drug ingredients of unknown
  origin and identity as well as additives- sugar,
  starch, quinine to dilute potency.
• Forensic chemist or toxicologist can expect any
  number of known and unknown substances submitted
  for analysis
• this problem makes it difficult for running
  tests since multiple tests may be necessary for
  unknown substance
• Two types of tests are performed qualitative
  (presence/absence) and quantitative (amounts)

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Drug Identification

• There are 2 general types of tests qualitative
  and instrumental
• Qualitative tests such as presumptive, TLC and
  microcrystalline are fast, easy, relatively
  cheap, but are qualitative and may be influenced
  by other chemicals or drugs in the sample
• Instrumental tests are expensive, time consuming,
  but are more definitive and less influenced by
  contaminants

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Presumptive (Color Tests)

• COLOR TESTS many drug tests yield characteristics
  of color when brought into contact with chemical
  reagents.
• Color tests are used as screening tests and not
  conclusive.
• Impurities may affect the test

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2 Primary Color Test Reagents

• Marquis (2 formaldehyde in sulfuric acid)
• Reagent turns purple in the presence of heroine
  and morphine and most opium derivatives
• Will become orange-brown when mixed with
  methamphetamine

Heroin
Meth
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2 Primary Color Test Reagents

• Scott Test (A2 cobalt thiocyanate dissolved in
  water and glycerin, B concentrated hydrochloric
  acid C chloroform)
• A powder containing cocaine will turn solution A
  blue, addition of B will result in a clear pink
  color, then addition of C the blue color will
  reappear in the chloroform layer

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Microcrystalline Tests
Cocaine

• MICROCRYSTALLINE TEST- drop of chemical reagent
  is added to small quantity of the drug
• A chemical reaction ensues producing crystals
• measure size and shape of crystals
• characteristic patterns for known drugs.
• This technique is considerably more specific than
  color tests
• Hundreds of crystalline tests have been developed
  to identify the most commonly used drugs

Methamphetamine
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Chromatography

• The techniques of thin layer and gas
  chromatography are especially well designed for
  drug analysis.
• Since the chromatograph or retention times must
  be compared the analysis must have some idea of
  what to compare the unknown too
• Thus chromatography is a good follow up for
  either color or microcrystalline tests

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Bioterrorism Agents

• Ricin is lethal in humans in quantities as small
  as 500 micrograms-size of the head of a pin
• It can be inhaled as a powder, ingested in
  food/drink, or injected into the skin.
• Anthrax is caused by a bacteria that forms
  spores.
• It can be inhaled, ingested, or absorbed through
  the skin