forensic toxicology of alcohol Flashcards
forensic toxicology
how drugs and poisons affect humans
when a person ingests a drug or a poison it is absorbed into the bloodstream circulates through the body has intended and unintended effects and then is eliminated
f
forensic toxicologists
deceased
help determine COD
living
usually drunk or drugged driving cases
drug
chemical or chemical mixture that is designed to have one or more physiological and or psychological effects on a person
poison
substance that has a toxic life threatening effect on a person
forensic toxicologist
determines the identity of all drugs and poisons present in the body
determines the quantities of drugs and poisons present in body
determines metabolites secondary products of drugs present
determines interactions of drugs present
helps determine history or pattern of drug use by the person involved
pharmacokinetics
how drugs move into and out of body
four processes taking place
absorption
passage of the drug through a tissue layer of the body
distribution
dispersion of the drug throughout the body
metabolism
process by which drug is chemically changed to a chemically different but related substance, metabolite
elimination
method of removing drug from body
absorption
introduced by a number of means
oral intramuscular intravenous rectal topical subcutaneous inhalation
chemical nature and form of drug determines how easily it crosses tissue barrier
aspirin coated for slower absorption
may be controlled to reduce unwanted side effects
once the barrier is breached the drug will enter the bloodstream
oral ingestion is absorbed through the stomach or small intestine and the rate can be affected by other stomach contents
distribution
drugs are distributed through bloodstream
blood reaches every cell of body
although the blood stream reaches all tissues this doesn’t mean that the blood is the same concentration everywhere
more blood goes to some orgnas
some drugs have preferential attraction to certain tissue
metabolism
serves three purposes
deactivate the drug to have less effect
may be more soluble an easier to eliminate
ma convert substance that can be used by body’s cells for energy and easier elimination
mostly takes place in the liver
elimination
predominately done through excretion in urine
drug must be water soluble, generally accomplished by liver
may also be done through respiration or perspiration if drug is volatile
pharmacodynamics
how drugs act in the body
some organs have receptors
drugs bind with certain receptors
receptor fulfills a particular function or process
agonist
drug that binds to receptor and causes the process
antagonist
drug that binds to receptor and does not cause the process
can block or reverse action of agonist
heroin and narcan
tolerance
phenomenon where he body organ systems adapt to drug
caused by decrease in sensitivity or number of receptors
synergism
effect of two or more drugs being greater when taken together than their effects separately
alcohol and barbituates
bot CNS depressants
identification of drugs in the body
may be difficult to do once ingested and distributed
small doses conc may be low
some drugs prefer certain tissues, hard to find
steps for identification
sampling, extraction, screening, confirmation
sampling
urine is used to screen for drugs
blood confirms presence of drug and determines its conc
hair can trap and hold drugs for as long as hair is on the body
extraction
once a tissue or liquid (blood or urine) has been removed
drug must be extracted
makes analysis easier
keeps interment clean and unglogged
concentrates drug so it is easier to detect
liquid phase extraction
separates liquids based on pH
not appropriate for a mixture of drugs with similar pH values
will be extracted together and not separated
solid phase microextraction
useful for mixtures with similar pH values
specifically coated wire is inserted into fluid with drugs
drugs are selectively adsorbed onto wire
drugs eluted for further analysis
screening
preliminary test for drugs in the body fluids
useful if you don’t know what drugs were ingested
panel of the most commonly abused drugs
two types
chromatographic tests
thin layer chromatography
gas chromatography
immunoassay tests
immunoassay tests EMIT
similar to species test for blood
EMIT
enzyme multiplet immunoassay test
uses drug antibodies aded to evidence sample
antibodies bind to drug if present
known amount of the suspended drug that has been labeled with an enzyme is added and any unbound antibodies bind
this enzyme labeled drug is measured and correlated to the concentration of the antibodies
determining the amount of drug
immunoassay tests RIA
radioimmunoassay
similar to EMIT, but antigens are radioactively labeled
