Ch. 6 - Forensic Toxicology: Analysis, Poisons, and Post-Mortem Samples

Who is considered a key figure in the history of forensic toxicology?

Mathieu Orfila

What does forensic toxicology focus on?

Biological samples from living and deceased individuals.

What is the role of forensic toxicologists?

To analyze blood and tissues for drugs, poisons, and metabolites.

What is a xenobiotic?

A foreign substance not naturally found in the body.

What is the phrase that summarizes the concept of toxicity?

"The dose makes the poison."

What is the therapeutic dose?

The amount needed for the desired effect.

What does LD50 represent?

The single dose lethal to 50% of a population.

What factors can affect the lethal dose of a substance?

Body weight and individual susceptibility.

What are the four phases of ADME in pharmacology?

Absorption, Distribution, Metabolism, Excretion.

What is first-pass metabolism?

The process where drugs are metabolized in the liver before entering general circulation.

How does the mode of ingestion affect drug absorption?

It affects the speed and intensity of the drug's effects.

What happens to drugs and metabolites in the body?

They can be absorbed by tissues, filtered into urine, or deposited in hair.

Why is the timing of sample collection critical in forensic toxicology?

It affects the interpretation of drug concentration and effects.

What is the effective dose (ED50)?

The dose required to achieve the desired effect in 50% of the population.

What are common post-mortem samples analyzed in forensic toxicology?

Blood, tissues, and other biological fluids.

What is the significance of the Marie La Farge arsenic case?

It is a historical example of forensic toxicology's role in death investigations.

What is the difference between forensic toxicology and seized drug analysis?

Forensic toxicology focuses on biological samples, while seized drug analysis focuses on pills and powders.

What is the impact of repeated doses on drug concentration?

Repeated doses are needed to maintain a therapeutic level in the bloodstream.

What is the consequence of first-pass metabolism on drug efficacy?

It often decreases the amount of effective drug that enters circulation.

How do drugs enter the bloodstream when ingested orally?

They are absorbed through the digestive tract and then metabolized in the liver.

What is the typical lethal blood concentration associated with a substance?

It can vary based on the substance and individual factors.

What is the role of the medical examiner or coroner in forensic toxicology?

They issue the final ruling on cause and manner of death.

What is the significance of body weight in determining lethal doses?

Lethal doses are often reported in units of dose per body weight, such as mg/kg.

What is the relationship between drug absorption and the method of ingestion?

Different methods (oral, inhalation, injection) affect how quickly and effectively drugs are absorbed.

What happens to drugs after they enter the bloodstream?

They are distributed to tissues, metabolized, and eventually excreted.

What are the primary biological samples analyzed in forensic toxicology?

Urine, gastric contents, vitreous humor, bile, liver, and other tissues.

What is the Marsh Test used for?

To test tissues for arsenic.

What type of analysis does toxicology involve?

Qualitative analysis (what substance was ingested) and quantitative analysis (how much was taken).

What is the significance of the Orfila case in toxicology?

It is a famous case related to the identification of poisons in a murder investigation.

What is the principle behind immunoassay screening?

It is based on antigen-antibody reactions.

What are the limitations of immunoassay screening?

Limited by cross-reactivity and cannot definitively identify specific compounds.

What are the primary methods for substance identification in toxicology?

Mass spectrometry (MS) and chromatography.

How does blood alcohol testing work?

Blood is heated to evaporate ethanol into the headspace, which is then analyzed.

What is Henry's Law in the context of alcohol analysis?

It relates breath alcohol concentration to blood alcohol concentration, with blood being approximately 2100 times more concentrated.

What are the common types of poisoning?

Accidental, intentional, and homicidal poisoning.

What distinguishes opiates from opioids?

Opiates are derived from the opium poppy, while opioids are synthetic compounds.

What is the potency of carfentanil compared to morphine?

Carfentanil is approximately 100 times as potent as morphine.

What is a key challenge in interpreting toxicological findings?

Post-mortem redistribution and the context of death are critical for accurate interpretation.

What are some current trends in forensic toxicology?

Novel psychoactive substances, counterfeit pharmaceuticals, and fentanyl contamination.

What is the role of collaboration in toxicological analysis?

Collaboration with forensic pathologists and other forensic disciplines is essential for accurate interpretation.

What does bioavailability refer to in toxicology?

The extent and rate at which the active ingredient or active moiety is absorbed and becomes available at the site of action.

What is the significance of half-life in drug elimination?

Half-life determines the rate at which a drug is eliminated from the body.

What is the main purpose of toxicological analysis in death investigations?

To provide a comprehensive picture of the substances involved and their roles in death.

What is the importance of context in toxicological findings?

Context is critical for understanding how ingested substances affected the individual.

What does the term 'multiple drug interactions' refer to in toxicology?

The effects that occur when two or more drugs are taken together, which can alter their efficacy and toxicity.

What is the role of peer review in toxicological research?

Peer review is important for ensuring quality control in toxicological analysis.

What is the significance of reference standards in toxicology?

They are used for comparison to identify compounds during analysis.

What is the role of advanced analytical techniques in current toxicology?

They are used for detecting novel substances and improving the accuracy of analyses.

What is the relationship between mode of ingestion and toxicity?

The mode of ingestion can significantly affect the toxicity of a substance.