Transcript Toxicology Power Point

Drugs, Poisons and Forensic Toxicology
Read intro to ch.9 on Anna Nicole Smith’s Death
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
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
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
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
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Rapid (fast) breathing.
Dizziness.
Weakness.
Headache.
Nausea and vomiting.
Rapid heartbeat.
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
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
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
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)
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
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)
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
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 body’s “off switch” for muscles
• When this “off switch” does not work correctly,
muscles throughout the body have severe,
painful spasms. Even though the person’s
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
can’t breathe.
• This is allegedly one of the most painful deaths
imaginable as every muscle in your body
contracts
Brown Recluse-venom causes death
of soft tissue that may take months to heal and
can leave large, deep scars
Brown recluse bite
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
Drug Dependence
• Drug dependence varies based on the nature of
the drug, the route of administration, the dose,
the frequency of use and the individual’s rate of
metabolism
• Psychological needs arise from numerous
personal & social factors that stem from the
individual’s 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)
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)
Stimulants: Amphetamine
• AMPHETAMINESsynthetic 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
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.
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.
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.
DEPRESSANTSslow 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.
Hallucinogens: Marijuana
• MARIJUANA has been used legally and illegally for 3000 yrsreferences to it in medical and pharmacological uses.
• Was used for
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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
LSD & PCP
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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.
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.
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 1960’s and 70’s, the
average bag of heroin sold
contained 15-20% heroin.
Currently the average purity
is 35%.
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 additivessugar, 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)
Drug Identification
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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
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
2 Primary Color Test Reagents
1. Marquis (2% formaldehyde in sulfuric
acid)
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Reagent turns purple in the presence of
heroine and morphine and most opium
derivatives
Will become orange-brown when mixed with
methamphetamine
Heroin
Meth
2 Primary Color Test Reagents
2) Scott Test (A:2% cobalt
thiocyanate dissolved in
water and glycerin, B:
concentrated
hydrochloric acid; C:
chloroform)
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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
Microcrystalline Tests
Cocaine
• MICROCRYSTALLINE TESTdrop 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
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
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