PPT about forensic toxicology

1. Presented By Muhammad Abubakar Habib

2.  Branch of science concerned with the nature ,
effects and detection of poison.
ForensicToxicology.
 The science that deals with the medical and
legal aspects of harmful effects of chemicals
on human body.

3.  When anybody takes a drug or poison , it
absorbed into the blood stream and
circulates through the body where it has
effects on human body then it is eliminated
from body by different process.
 Toxicologist works to determine the cause
and manner of death. This may be a complex
problem for toxicologist in many cases.

4.  Drug use pattern.
 Physical condition at the time of ingestion.
 Amount and duration of ingestion
 Identity of drug
 Amount of other drugs that are in the body at
the same time

5.  Toxicologist also deals with the cases in
which person have taken drug but don’t die.
These cases include drunk or drug driving.

6.  The science that studies the relationship
between drugs and living things
 CLINICAL PHARCOLOGY
 This concerns with the effect of drugs on
human.This branch of pharmacology is called
toxicology.

7.  A Scientist who works on cases with
suspicious circumstances in which drugs are
involved in death, impairment or injury.

8.  A drug is a chemical mixture that is designed
to have one or more psychological and
physiological effects on a person. Drug is
designed to cause a particular response
where as poison is a substance that has life
threatening effect on a person.

9.  Some drugs may have side effects.These side
effects may be mild or severe and do not
occur in every body who takes drug.eg
allergic effects of some drugs.

10.  Forensic toxicologist must accompanied
different tasks to know about role of drug in
causing death.
 Identity of drugs in poisons present in the
body
 Quantity of drug in the body at the time of
death
 The secondary products of drugs that are
present in body

11.  Synergistic effect
 History and pattern of drugs
 Tolerance of drugs

12.  Pharmacokinetics concerns with how drugs
move into and out of the body.
 Pharmacokinetics are defined by four
processes
 Absorption
 Distribution
 Metabolism
 elimination

13.  When the drug is ingested, all processes walk
together and establish dynamic equilibrium
with in the body

14.  Drug can be injected in the body by different
ways including
 Oral
 Intramuscular
 Intra venous
 Rectal
 Topical
 Subcutaneous
 Inhalation

15.  In all these methods the drug is pass through
tissue barrier such as skin,nasal
passage,intestine and stomach.
 To which extent drug can cross the barrier
depends on the chemical nature of drug.
 Drug can be distributed in the body by
 Tissue
 Blood stream

16.  The distribution of drug in the body is done
through blood circulation.Some portion of
drug may be bound to blood protein.Through
blood circulation blood reaches to whole body
or organs.But the concentration of drug is not
same everywhere because some organ like
brain,heart and liver receive more of the blood
supply then other organ so these organ will be
more effected by drug.

17.  Distribution of drug also depends upon
chemical nature of drug

18.  Metabolite
 Through the process of metabolism drugs or
other substances are chemicaly changed to
different substances called metabolite.

19.  It may deactivates the drug.
 Metabolite is more water soluble
 Elimination through urination is easier.
 Drug is converted into the substances that can
be used by body cell for energy purpose.
 Most metabolism takes through liver. Series of
metabolic reactions take place and one
metabolite is converted into further another
substance.

20.  Drug can be removed easily by elimination.
Mainly drug is removed by urination. For this
removal drug must be water soluble.
 Drug can be eliminated by respiration.
 Drug can also be eliminated by perspiration.
 For example alcohol.

21.  Pharmacodynamics
Study of how drug act in the body is called
pharmacodynamics.
Drug binds to the receptor cells and allow the cell
to perform particular functions.The function
performed by the cell depends upon the
receptor bind to the cell.
Agonist
The drug that bind to a particular receptor and
cause it to perform some function that drug is
called agonist

22.  Antagonist
 A drug that binds to the receptor and stops the
biological process.
 Example; action of heroin and other narcotice
 Heroin works as agonist and Naloxone acts as
antagonist to heroin.
 Effective dose of drug for therapy depends
upon;
 Person physicall condition
 Severity of illness

23.  Toxicologist determines the effects of drug
 Criteria for drug decision includes;
 Degree to which subject is addicted
 Experience of the person with drug overtime
 Cumulative effects of multiple drug
Addiction AndWithdrawal
 Withdrawal syndrome occurs in the individuals
who have developed physiological dependence
on drug or alcohol and who discontinue or
reduce their use of it.

24.  For example
 Addiction to barbiturates… its sudden
withdrawal can be fatal.
 Dependence on the drug may be physical or
psychological.
 Tolerance
 Chemical tolerance is a phenomenon
whereby the body’s organ systems adapt to
the drug.

25.  Most drugs has exhibit tolerance to one
degree while some drugs has more tolerance
for example;
 Opium based narcotics such as morphine and
heroin as well as coccain and barbiturates.
 If the drug intake is stopped, body takes a
long time to recover.

26.  When various parts of body works together to
have enhance effect we called it synergism.
Drugs in the body also works synergistically.
 Two or more drugs taken together will have
more effect on the body than the single drug.
 Forensic toxicologist must be aware of
synergistic effect.
 For example synergism of alcohol and
barbiturates

27.  Alcohol and barbiturate both have same
function. Both depresses the central nervous
system. But their action of mechanism for both
is different.
 Barbiturate depresses the CNS and reduces
the activity of nerves causing relaxation.
 It slows down the functions of body and cause
drowsiness and even sleep.
 Alcohol is also depressant drug .

28.  It slows down the messages that travels
between the body and brain.
 When these both drugs work together their
combinne effect is more than their single
effect.
 The combination of substance become the
cause of death of two superstars
 Janice joplin
 Jimi Hendrix

29. Synergism is the easiest to detect if someone
takes two drugs and has effect that would not
be expected from either of them.

30.  Once a drug is ingested and distributed in body ,it will
difficult to identify.
 There may be no information about what drug or drugs
person may have taken and how much was taken.
 The process of drugs identification involve following very
important steps
1. Sampling
2. Extraction
3. Screening
4. Confirmation

31.  Sampling:
 Sample taken from body depends upon the condition of
body and most likely place for drug to congregate.
 If the person is alive sample will be taken from blood , urine ,
hair and if the person is dead all the above available with
other tissues such as brain, liver ,spinal fluid .
1. Stomach
 If the person took drug and die in a short time ,Some of the
digested and un-digested present in stomach ,we could took
sample from stomach.

32.  Urine
 In urine drug concentration and metabolites are
greater therefore It is used as an ideal medium
for screening of some drugs.
 Blood
 Drug concentration are not same in blood an
urine.
 So it is good scientific practice to use
1. Urine sample to screen possible presence of
drug.
2. Blood is used to find out the concentration of
drug and confirmation of its presence.

33.  Hair
 In the past past few years ,hair also Used for
drug analysis.
 As urine and blood it can also hold drugs fir
months and information about the pattern
and frequency of ingestion.

34.  Extraction:
 Once a tissue or fluid identify and removed
drug must be extracted.
 There are several methods for the effective
extraction of drug.
 The one chosen Ina a particular case depends
upon the drug and tissue of fluid.
 Liquid phase
 For efficient separation a toxicologist must
Known the range of ph of drug.
 Acid pH 1__7
 Base pH 7__14

35.  pH dictates the method of extraction.
 Example
 We have a sample of urine Containing cocaine.
urine is an acidic and cocaine is a basic drug.
 In acidic medium
 In acidic medium cocaine is present in Salt(Ionic)
form.
 Cocaine have H+ attached to it, there would be an
anion Such as Cl ion present.
 Cocaine is soluble in urine in acidic medium so for
the separation of cocaine from urine this medium
not useful.

36.  In basic medium
 Cocaine revert to its free base form.
 This form is not soluble in urine and aqueous
solution so cocaine easily precipitate out .
 Add organic solvent in a beaker have urine in
which cocaine is present.
 Organic solvent not mix with urine but with
cocaine .
 Thus cocaine efficiently separate from urine.

37.  Barbiturate extraction.
 It is an acidic drug.
 By using acidic extraction rather than basic
extraction , barbiturate extracted from urine.
 Limitations if liquid phase
 Liquid phase is not suitable two or more acidic
or basic are known to be present.
 Reason
 The reason is that all the acidic and basic drugs
will be extracted together.

38.  Solidphase
 The solid phase extraction of drug is very
popular from recent years.
 In solid phase extraction, a small column or
coated wire is used to extract the drug out of
urine or blood.
 The blood or urine is poured through a
speciall solid bed that selectively removes the
drug.

39.  The bed is then washed to strip off the drug
for further analysis.
 Solid phase microextraction
 In this type of extraction, a specially coated
wire , strip or fiber is inserted into fluid that
contains drug or drugs.
 This is capable of capturing and measuring
very small amount of drug

41.  Screening
 These are introductory test fordrugs in body
fluid.
 This is used to test wether the drug is present
or not. But it does not confirm the presence
of drug.
 It is important in the case in which we
toxicologist does not know that which drug
or drugs are ingested.

42.  Categories of screening test;
 Chromatographic
 Immunoassy
 Chromatographic tests are gas chromatography
or thin layer chromatography.
 ImmunoassayTechnique
 This test is used to test for the presence of an
antibody in a blood or fluid sample.
 The contains specific antigen as a part of
detection system.

43.  IMMUNO
 Responce that cause the body to generate
antibody.
 Assay
 Refers to test
 Immunoassay is the test that uses antibody
and antigen complex.
 Antigens
 These are the substances that stimulate the
immune system to produce antibodies.

44.  Antibody
 It is also called immunoglobins.Y-shaped
proteins produce by body that help fight
against antigen.
 In this technique antigen antibody reaction
used to detect the drug.
 In this technique extraction of drug from
urine is not necessary.

45.  Enzyme multiplied immunoassay test
 it is one of the most popular test.
 It is an immunoassy in which drug or
metabolites in sample compared with a drug or
metabolite labelled with enzyme to bind an
antibody.
 Methampheramine;
 Is a central nervous system stimulant used as a
recreational drug. Its a powerful highly
addictive drug.

46.  Methamphetamine injected into rabbits body.
When it enters immune system produce
antibody to this drug.
 Now these antibodies are injected into the
urine of human for testing. Now if there is
methamphetamine in urine . It will
immediately bind to these antibodies.
 Now , known amount of methamphetamine
which is labelled with enzyme is added to
urine.

47.  Antibodies from rabbit did not react with
methamphetamine in urine.They will now react
with enzyme labelled methamphetamine.
 In this way when antibody attack on this labelled
antigen thus decrease its concentration.
 There is a corelation between
concentration/quantity/amount of antibodies and
with methamphetamine in urine.
 we can determine the amount of
methamphetamine or drug by this process.

48. In this technique antigens are radioactively
labelled.
In RIA and EMIT we dont sure about that
antibodies which will produce are specific to
that drug which we injected.
For example;
If we inject methamphetamine into rabbit then
body will produce antibodies that can also
bind to pseudophedrine.

49.  In this way RIA will give false +ve test .
 So other suitable test is required.
 CONFORMATION
After the completion of screening test, drugs
must be confirmed.
Mass spectrometry;
*its an analytical technique.
*it is used to measure the mass to charge ratio
of ions.

50.  Mass spectrum of the result is formed
 In forensic toxicology , two independent test
having different principles performed for
conformation is not accepted.
 Cut off level
 Limit of detection
 Every instrument create some electronic noise.
 if signal for the presence of drug is too weak, it
will not be seen above noise.
 Each laboratory set a cut off level for each drug.
 Drug is not detected, if drug is found the below
the cut off level.

51.  For example;
 *cut off level for cocaine may be
set at 50 ng/mL.