Forensic Toxicology Overview

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Questions and Answers

What type of interaction occurs when the combined effect of two substances is greater than the sum of their individual effects?

  • Additive effect
  • Antagonism
  • Synergism (correct)
  • Idiosyncrasy

How does the pH of the stomach affect aspirin toxicity?

  • Higher pH decreases toxicity
  • Lower pH increases toxicity (correct)
  • Stomach pH does not influence toxicity
  • Higher pH increases toxicity

In which condition would you expect to see a decreased metabolism of poisons?

  • Renal disease (correct)
  • Normal cardiac function
  • High dietary fiber intake
  • Healthy liver function

What is the relationship between hypersensitivity and drug response?

<p>Hypersensitivity reflects an allergic reaction to specific drugs (C)</p> Signup and view all the answers

In individuals with G6PD deficiency, what type of toxic reaction occurs when exposed to certain drugs?

<p>Idiosyncratic reaction (B)</p> Signup and view all the answers

What does forensic toxicology primarily focus on?

<p>The medicolegal aspects of harmful effects of chemicals on humans (B)</p> Signup and view all the answers

Which two figures are considered pivotal in the history of toxicology?

<p>Paracelsus and Mathieu Orfila (D)</p> Signup and view all the answers

Which of the following forms of toxins is NOT classified as a gaseous substance?

<p>Household cleaning supplies (D)</p> Signup and view all the answers

What generally increases the severity of toxic symptoms from a particular poison?

<p>The quantity of the substance administered (A)</p> Signup and view all the answers

Which organ is primarily targeted by CNS depressants?

<p>Central Nervous System (A)</p> Signup and view all the answers

Which factor is NOT mentioned as modifying toxic effects?

<p>Time of day (C)</p> Signup and view all the answers

Which type of poison is characterized by having both local and remote sites of action?

<p>Metals (C)</p> Signup and view all the answers

What is the absorption rate of gases compared to solids and liquids?

<p>Gases are absorbed faster than liquids and solids (A)</p> Signup and view all the answers

Flashcards

Synergism

When two or more substances interact, their combined effect is greater than the sum of their individual effects. For example, taking alcohol and barbiturates together can result in a much stronger sedative effect than either substance alone.

Antagonism

The opposite of synergism. Two substances interact and the effect is less than what would be expected if they were acting alone. For example, giving BAL (British Anti-Lewisite) to someone poisoned with lead can help to reduce the lead's toxicity.

How stomach acidity affects drug toxicity

The acidity of the stomach can increase the toxicity of certain medications, like aspirin. A more acidic stomach environment means more aspirin is absorbed and can lead to more severe side effects.

Age and toxicity

A person's age can significantly influence their response to toxins. Very young and very old individuals are more susceptible to experiencing severe effects from poisons.

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Liver disease and toxicity

Individuals with pre-existing liver diseases are more prone to toxic effects because their liver is less efficient at breaking down and eliminating toxins from the body.

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Toxicology

The study of the harmful effects of chemicals on living organisms, including symptoms, mechanisms, treatment, and detection of poisoning, especially in humans.

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Forensic Toxicology

A branch of toxicology that focuses on the medicolegal aspects of harmful chemical effects on humans, combining toxicology principles with analytical chemistry.

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Toxin

Any substance that exerts a harmful effect on a living organism.

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Poison Classification by Nature

The classification of poisons based on their physical state, like gases, liquids, or solids.

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Poison Classification by Target Organ

Poisons classified by their primary action, like affecting the central nervous system, gastrointestinal tract, kidneys, liver, cardiovascular system, or lungs.

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Factors Modifying Toxic Effects

The amount of a toxin that is absorbed, how quickly it is absorbed, and the route of administration can all influence its effects.

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Cumulation

The rate at which a toxin enters the body compared to the rate it is eliminated. If intake exceeds elimination, the toxin can build up in the body.

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Route of Administration

The way a toxin is introduced into the body, such as intravenously, inhalation, intramuscularly, through the skin, or through mucous membranes.

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Study Notes

Forensic Toxicology

  • Toxicology is the study of the harmful effects of chemicals on living organisms.
  • It includes studying symptoms, mechanisms, treatment, and detecting poisoning, especially in humans.
  • The Greek words toxicos (arrow) and logos (study) are roots of the word toxicology
  • Paracelsus is considered the father of toxicology
  • He stated: "All things are poisons and nothing is without poison, only the dose makes a thing a poison."

Forms of Toxins

  • Toxins can be gaseous (e.g., carbon monoxide, cyanide).
  • Toxins can be liquid (e.g., household cleaning supplies, alcohol).
  • Toxins can be solid (e.g., solid drugs).

Classification of Poisons

  • Nature: Poisons can be solid, liquid, or gaseous.
  • Site of Action:
    • Local: Inorganic corrosives.
    • Remote: Alkaloids and most therapeutics.
    • Local and remote: Metals and organic corrosives.

Target Organs

  • Central Nervous System (CNS) stimulants: Amphetamines and cocaine.
  • CNS depressants: Hypnotics, sedatives, narcotics, alcohol, anesthetics.
  • Gastrointestinal Tract (GIT): Metals and corrosives.
  • Kidneys: Mercury and cadmium.
  • Liver: Paracetamol and iron.
  • Cardiovascular System (CVS): Digitalis
  • Lungs: Metal fumes

Factors Modifying Toxic Effects

  • Poison Quantity: Increasing the dose increases the severity of symptoms.
  • Poison Quality: Gases are rapidly absorbed more quickly than liquids or solids (and powders faster than lumps) .
  • Route of Administration: The way a poison is introduced to the body (e.g., intravenous (IV), inhalation, intramuscular (IM), skin, mucous membrane) affects its absorption.
  • Poison Cumulation: The rate of poison intake must be considered alongside the rate of elimination.
  • Chemical Interaction:
    • Addition: The effect is the sum of the individual effects (e.g., aspirin + paracetamol).
    • Synergism: The combined effect is greater than the sum of the individual effects (e.g., alcohol + barbiturate).
    • Antagonism: The effect of one substance counteracts the effect of another substance (e.g., BAL + lead).

Patient Factors

  • Gastrointestinal Tract (GIT): The pH of the stomach (acidic) increases the toxin HCl, which increases the toxicity of aspirin; amount of food impacts the absorption, empty stomachs increase toxicity.

  • Type of Food: Fatty meals increase absorption of fat-soluble poisons.

  • Age: Toxic effects are more severe in extremes of age.

  • Health: Underlying health conditions like liver or kidney disease impact the body’s ability to process, metabolize or excrete poisons. Liver diseases decrease metabolism, kidney diseases decrease excretion.

  • Toxicogenetics: Abnormal responses to drugs due to genetic factors (e.g., favism with sulphonamides). G6PD Deficiency→Hyltic anemia

  • Hypersensitivity: Exaggerated responses to drugs, like those caused by aspirin or penicillin allergies (Ag-Ab reaction).

  • Tolerance: Addicts can tolerate higher doses of drugs (like opium, barbiturates, amphetamines) than normal individuals without serious repercussions.

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