Toxicology Flashcards by Clodagh cultra

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What is toxicology?

Study of the adverse effects of chemical, biological and physical agents on living systems

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What are the key responsibilities for a forensic toxicologist?

-Toxicological analysis
-Report and document
-Consult and testifying
-R & D

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What are poisons?

-A substance that can cause the illness or death of a living organism

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What are the most frequent occurrences of poisoning?

-Social and economic stress or mental disorders
-Illicit substance abuse
-Administered against will
-Unintentional/accidental

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What is the NPIS?

National Poisons Information Service

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What is the role of the NPIS?

Advise NHS healthcare professionals on the diagnosis, treatment and care of poisoned patients

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What is the importance of case notes?

-History of patient/deceased
-Signs and symptoms on admission
-Materials found near the patient or body, e.g. pill containers
-Lab investigation result
-Post mortem exam

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What is the chain of custody?

Process that tracks the movement of evidence

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How is chain of custody maintained?

-Validity of specimen tests
-Chronological disposition and condition of specimen
-Collection: Time, date, what it is, by whom, tamper

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What does the misuse of drugs act state?

Offence to:
-Possess controlled substances
-Possess with intent to supply
-Supply controlled drugs
-Allow a house, flat or office to be used by people taking drugs

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What are the main classes of mis-used drugs?

-Opiates (morphine, heroin)
-Depressants (alcohol, barbiturates)
-Minor tranquilisers
-Stimulants (cocaine, ecstacy)
-Hallucinogens (LSD, mushrooms)
-Others, e.g. cannabis, nicotine

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What are class B drugs?

-Cannabis
-Barbiturates
-Codeine
-Amphetamines (powder)

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What are class A drugs?

-Cocaine
-Amphetamines (i.v)
-Ecstasy
-Magic mushrooms
-Meth

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What are class C drugs?

-GHB
-Diazepam
-Anabolic steroids
-Ketamine

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What are stimulant drugs?

-Stimulate brain activity
-E.g. cocaine, amphetamine

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What are depressant drugs?

-Inhibits brain activity
-E.g. Alcohol, Heroin, Barbiturates

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What are hallucinogenic drugs?

-Alteration in mood and perception
-E.g. ecstasy, LSD, cannabis

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What is the role of the toxicologist in summary?

-Maintain chain of custody
-Identify drugs and poisons
-Screen entire body
-Search for parent chemicals and metabolites

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What is the cause of anion poisoning?

-Cyanide
-Fluoride
-Nitrate
-Oxolate

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What is the cause of corrosive poisoning?

-Sulphuric acid
-Sodium hydroxide

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What is the cause of gas and volatile poisoning?

-Ethanol
-Combustion products
-Solvents

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What is the cause of metal and metalloid poisoning?

-Iron
-Lead
-Arsenic

What is the cause of toxin poisoning?

-Plant -Animal -Bacterial -Fungi

What is the cause of pesticide poisoning?

-Herbicides -Organophosphates

What is acute exposure?

-Contact with a substance that occurs once or only for a short time

What is chronic exposure?

Contact with a substance that occurs over a long time

What are typical symptoms of poisoning?

-Nausea -Vomiting -Seizure -Coma -Death

What are neurological symptoms of poisoning?

-CNS depression -CNS stimulation

What are cardiovascular symptoms of poisoning?

-Dysrythmia -Hypotension/hypertension

What are drugs of abuse?

-Any substance used for an alternative purpose than that intended

What are illicit drugs?

-Highly addictive -Illegal to sell, make and use -Not for medical purposes, illegal in this setting

What are the effects of ecstasy?

-Emotions of love and empathy -Increased serotonin and dopamine

What are the effects of LSD?

-Open/closed eye visuals -Time distortion -Increase of glutamate in the cerebral cortex

What are the effects of cocaine?

-Increased alertness & euphoria -Stimulates CNS

What are the effects of magic mushrooms?

-Hallucinogen -Linked with monoamine oxidase pathway

What are the effects of amphetamines?

-Wakefullness -Anorexia -Increased serotonin

What are the effects of cannabis?

-Euphoria & paranoia -Cannabinoid receptor and CNS

What is the aim of toxicological screening techniques?

-Confirm and quantify the chemical

What are the toxicological screening techniques?

-Immunoassays -Spot colour tests -TLC -GC -HPLC -MS

What are the steps to toxicological analysis?

-Separation of poisons from biological material -Identification -Confirm identity -Interpretation -Quantification

What are presumptive tests?

-Qualitative -Cheap -Fast -Rely on colour changes -Requires a blank and +ve control -Unreliable

What are examples of presumptive tests?

-Marquis test -Mandelins test -Cobalt isothiocyanate

How are immunoassays conducted?

-Drug labelled with enzyme & fluorescent marker -Interaction with the drugs and antibody Examples: EMIT, FPIA, CEDIA

How does mass spectrometry detect components?

-Analytes are separated on a column and passed to MS -analytes are ionized, fragmented and detected -Separated by mass to charge ratios

What is ADMET?

A: Absorption D: Distribution M:Metabolism E: Excretion T: Toxicity

What does absorption refer to (ADMET)?

-Route of administration/exposure E.g: -Intravenous -Dermal -Intramuscular -Ocular -Oral -Inhalation

What does distribution refer to (ADMET)?

-Movement of a drug/chemical around the body, into and out of tissues and fluids

What does excretion/elimination refer to (ADMET)?

Elimination= Irreversible loss of drug from the body via either metabloism or excretion Excretion = Removal of intact drug from the body

What are the factors affecting the passage of drugs through the cell membranes?

-Water solubility -Lipid solubility -Degree of ionisation -Active transport -Plasma protein binding

What is drug metabolism?

The enzyme-catalysed conversion of a drug into a chemically-distinct product (metabolite)

What is half-life (t 1/2)?

Time taken for drug concentration to decline by half

What is bioavailability?

Amount absorbed relative to the dose administered

How do you calculate bioavailability?

F = AUC (oral)/ AUC (i.v)

How do you plot dose response curves?

-Plot % response against log of dosage -Determine the lethal dose which kills 50%

What is postmortem redistribution?

-As time interval between death and blood collection increases, drug in heart and blood increases

What is the order of drug collection in postmortem redistribution?

1. Femoral 2. Iliac 3. Subclavian vessels 4. Heart

What is used to determine drug concentration in the absence of blood?

Liver