Questions Set-2 Forensic Toxicology

FORENSIC TOXICOLOGY

1. Which of the following factors is most likely to influence the half-life of a drug in a postmortem environment?

a) The rate of metabolism of the drug in the liver

b) The body’s temperature at the time of death

c) The method of drug administration (oral, intravenous, etc.)

d) All of the above

 

Answer: d) All of the above

Explanation:

The half-life of a drug refers to the time it takes for the concentration of the drug in the body to reduce by half. Several factors can influence the half-life of a drug in a postmortem environment:

Metabolism in the liver: Drugs are typically metabolized in the liver, and postmortem metabolic processes may differ from when the person was alive. The liver's functionality can influence how long a drug stays in the system.

Body temperature: A lower body temperature slows down metabolic processes, which can extend the half-life of certain drugs after death.

Method of administration: The way a drug was administered (e.g., orally or intravenously) can affect how quickly it is absorbed and distributed in the body, influencing its postmortem half-life.

 

2. In a postmortem analysis, which tissue is considered the most reliable for detecting chronic exposure to a substance, such as heavy metals?

a) Blood

b) Urine

c) Liver

d) Hair

 

Answer: d) Hair

Explanation:

Hair is considered a reliable matrix for detecting chronic exposure to certain substances like heavy metals or drugs, as it provides a long-term record of exposure. Substances are deposited into the hair shaft as it grows, so analyzing hair samples can help identify prolonged exposure to toxins over weeks, months, or even years. While blood and urine reflect more recent exposure, hair can offer a clearer picture of long-term accumulation.

 

3. Which of the following is the most common biomarker used to detect alcohol intoxication in a postmortem toxicology case?

a) Acetone

b) Ethanol

c) Methanol

d) GABA

 

Answer: b) Ethanol

Explanation:

Ethanol is the biomarker most commonly tested for in alcohol intoxication cases. It is the type of alcohol typically found in alcoholic beverages. Forensic toxicologists test for ethanol levels in blood, urine, and other biological fluids to determine if alcohol intoxication contributed to the cause of death. Acetone and methanol are also alcohols but are toxic and usually detected in cases of poisoning, while GABA is a neurotransmitter related to alcohol’s effects on the brain, not a direct marker for intoxication.

 

4. The term "morphine equivalency" is often used in forensic toxicology to quantify the effect of opioid drugs. Which of the following drugs is NOT converted into morphine in the body?

a) Heroin

b) Codeine

c) Oxycodone

d) Hydromorphone

 

Answer: c) Oxycodone

Explanation:

Oxycodone is an opioid analgesic that is not metabolized into morphine in the body. Unlike heroin (which is metabolized to morphine), codeine (which is converted to morphine) and hydromorphone (a metabolite of hydrocodone), oxycodone has a distinct metabolic pathway and is not directly converted to morphine. The concept of morphine equivalency is often used to compare the potency of different opioids by considering their metabolic pathways and effects on the body.

 

5. What is the primary difference between qualitative and quantitative analysis in forensic toxicology?

a) Qualitative analysis identifies the presence of drugs, while quantitative analysis measures the amount of the drug.

b) Qualitative analysis measures drug concentration, while quantitative analysis detects the presence of drugs.

c) Qualitative analysis is faster than quantitative analysis.

d) There is no difference; both terms mean the same thing in toxicology.

 

Answer: a) Qualitative analysis identifies the presence of drugs, while quantitative analysis measures the amount of the drug.

Explanation:

In forensic toxicology:

Qualitative analysis is used to identify what substances are present in a biological sample. This type of analysis typically uses techniques like immunoassays or chromatography to determine the presence of drugs or poisons.

Quantitative analysis measures how much of a substance is present. This is often done using techniques such as gas chromatography-mass spectrometry (GC-MS) or high-performance liquid chromatography (HPLC), which can precisely quantify drug concentrations.

 

6. Which of the following drugs can cause a false positive in an immunoassay test for marijuana (THC)?

a) Cocaine

b) Amphetamines

c) Ibuprofen

d) Diazepam

 

Answer: c) Ibuprofen

Explanation:

Ibuprofen, a common nonsteroidal anti-inflammatory drug (NSAID), is known to cause false positives in some immunoassay tests for THC. Although THC and ibuprofen have different chemical structures, some immunoassays may cross-react with substances like ibuprofen, leading to inaccurate results. Immunoassay tests are generally screening tests and can produce false positives, which is why confirmatory testing (e.g., GC-MS) is essential in forensic toxicology.

 

7. What is the "rat poison" most commonly associated with warfarin-like effects in forensic toxicology?

a) Strychnine

b) Cyanide

c) Bromadiolone

d) Arsenic

 

Answer: c) Bromadiolone

Explanation:

Bromadiolone is a rodenticide that works similarly to warfarin, an anticoagulant drug, by inhibiting vitamin K epoxide reductase and preventing the synthesis of clotting factors. It causes hemorrhaging by preventing blood from clotting. Forensic toxicologists may test for bromadiolone in suspected cases of poisoning. While strychnine and cyanide are highly toxic poisons, they work through different mechanisms.

 

8. In cases of suspected methanol poisoning, which metabolic byproduct is typically tested for in blood or urine to confirm exposure?

a) Acetate

b) Acetone

c) Formaldehyde

d) Formic acid

 

Answer: d) Formic acid

Explanation:

Methanol is metabolized in the liver to formaldehyde, which is further metabolized to formic acid. Formic acid is the toxic substance that leads to the damaging effects of methanol poisoning, including metabolic acidosis, visual disturbances, and central nervous system depression. Forensic toxicologists look for elevated levels of formic acid in biological samples to confirm methanol poisoning.

 

9. Why is postmortem toxicology often more complicated than clinical toxicology?

a) The drug distribution and metabolism continue after death, complicating results.

b) Postmortem samples are often contaminated by environmental factors.

c) The concentration of drugs can decrease due to decomposition processes.

d) All of the above

 

Answer: d) All of the above

Explanation:

Postmortem toxicology is more complicated than clinical toxicology due to several factors:

Postmortem redistribution: After death, drugs in the blood may move to other tissues, leading to inaccurate drug concentrations in the blood.

Environmental contamination: Biological samples (e.g., blood, urine) collected postmortem can be exposed to environmental contaminants, affecting the test results.

Decomposition: The breakdown of tissues and cells after death can lead to changes in the concentration of drugs and poisons in the body, complicating interpretation.

 

10. What is the primary purpose of conducting "controlled substance profiling" in forensic toxicology?

a) To identify a specific drug's concentration in the blood

b) To determine whether a person was under the influence of a drug during an incident

c) To differentiate between drugs with similar chemical structures

d) To identify the exact method of drug administration

 

Answer: b) To determine whether a person was under the influence of a drug during an incident

Explanation:

Controlled substance profiling is a method used to analyze the presence and concentration of various substances in a biological sample. It can help determine whether a person was under the influence of a drug at the time of a particular event (e.g., a car accident or a criminal offense). This type of profiling involves analyzing a variety of drugs, their metabolites, and their effects on the individual.