to Toxicology in Nonclinical Drug
Development
3rd Edition
Editor: Ali S. Faqi
,Chapter 1: Introduction — A Comprehensive Guide to Toxicology in Nonclinical Drug Development
(3rd Edition, Editor: Ali S. Faqi)
1. What is the primary goal of nonclinical toxicology studies in drug development?
A. To determine the market potential of a drug
B. To ensure drugs are effective in humans
C. To evaluate the safety profile of new compounds before clinical trials
D. To reduce production costs of pharmaceuticals
Answer: C
Rationale: The primary purpose of nonclinical (preclinical) toxicology is to assess the safety of
compounds before they are administered to humans. These studies help identify potential adverse
effects, target organ toxicity, and dose-response relationships. This ensures human subjects in clinical
trials are not exposed to unnecessary risk.
2. Which regulatory guideline provides recommendations for the design and conduct of toxicology
studies?
A. FDA Form 1572
B. OECD Guidelines
C. HIPAA Regulations
D. DEA Schedule Control
Answer: B
Rationale: The Organisation for Economic Co-operation and Development (OECD) guidelines are
internationally recognized and provide standardized methods for conducting toxicology studies. These
guidelines are essential for ensuring regulatory compliance and generating reproducible, reliable data.
3. What does the term "NOAEL" stand for in toxicology studies?
A. No Outstanding Adverse Exposure Level
B. Non-Observable Adverse Effect Level
C. No Observed Adverse Effect Level
D. No Objective Analysis of Exposure Level
Answer: C
Rationale: NOAEL stands for "No Observed Adverse Effect Level." It is the highest dose at which there
were no statistically or biologically significant increases in the frequency or severity of adverse effects.
This value is crucial for determining safe starting doses in clinical trials.
4. What is the significance of Good Laboratory Practice (GLP) in nonclinical toxicology?
A. Ensures only large labs can conduct studies
B. Increases the financial returns of pharmaceutical companies
C. Ensures the quality, consistency, and integrity of toxicology studies
D. Reduces the time needed for drug approval
Answer: C
Rationale: GLP regulations ensure that nonclinical laboratory studies are planned, performed,
monitored, recorded, and reported in a reliable and reproducible manner. Compliance with GLP is
mandatory for regulatory submission of toxicology data.
,5. Which of the following is NOT a typical endpoint evaluated in general toxicology studies?
A. Clinical pathology
B. Histopathology
C. Pharmacokinetics
D. Advertising strategies
Answer: D
Rationale: General toxicology studies evaluate endpoints such as clinical observations, body weights,
food consumption, clinical pathology, and histopathology. Advertising strategies are part of commercial
operations and are unrelated to toxicological assessment.
6. What is the function of acute toxicity studies in drug development?
A. To determine chronic organ damage over years
B. To evaluate a drug’s marketing potential
C. To assess effects following a single or short-term dose
D. To study reproductive health impacts
Answer: C
Rationale: Acute toxicity studies assess the adverse effects of a compound following a single or short-
term exposure. They provide critical information on the lethal dose and guide the design of longer-term
studies.
7. Which species are most commonly used in nonclinical toxicology studies?
A. Cats and sheep
B. Mice and rats
C. Zebras and turtles
D. Gorillas and orangutans
Answer: B
Rationale: Rodents such as mice and rats are widely used due to their well-understood genetics, short
life cycles, and cost-effectiveness. Their use allows for effective extrapolation of potential human
responses.
8. In nonclinical toxicology, what does "target organ toxicity" refer to?
A. The intentional design of drug delivery systems
B. The most profitable part of the market
C. Adverse effects concentrated in a specific organ
D. Organs targeted for healing by the drug
Answer: C
Rationale: Target organ toxicity occurs when adverse effects of a substance are consistently observed in
a specific organ or system. Identifying this helps inform dose limitations and patient monitoring
strategies in clinical trials.
9. What is the typical duration of subchronic toxicity studies?
A. 2 days
B. 2 weeks
C. 1-3 months
D. 2 years
Answer: C
, Rationale: Subchronic studies usually last between 28 and 90 days. They provide insight into the
cumulative effects of repeated exposure and help bridge the gap between acute and chronic toxicity
data.
10. Why are two species typically used in toxicology studies for regulatory submission?
A. To increase costs
B. To satisfy marketing needs
C. To detect species-specific toxicities
D. To reduce animal usage
Answer: C
Rationale: Using two species (usually one rodent and one non-rodent) ensures that any species-specific
responses are detected, increasing the reliability of predictions for human safety.
11. What does "systemic toxicity" imply?
A. Toxic effects localized to the skin
B. Toxic effects that impact the entire body
C. A system of laws controlling drug use
D. Toxicity only in the digestive tract
Answer: B
Rationale: Systemic toxicity refers to adverse effects that are distributed throughout the body via the
circulatory system, often involving multiple organs and systems.
12. Which of the following is a reason for using animal models in toxicology?
A. To study tax laws
B. To predict human toxicity responses
C. To satisfy consumer demand
D. To avoid laboratory quality standards
Answer: B
Rationale: Animal models provide a controlled biological system that allows researchers to predict how
a compound may affect humans. Ethical use of animals is regulated and scientifically justified.
13. What is the LD50 value?
A. The lowest effective dose
B. Dose that causes death in 50% of a test population
C. Maximum tolerated dose
D. Dose that cures 50% of animals
Answer: B
Rationale: The LD50 (Lethal Dose 50%) is the amount of a substance required to cause death in 50% of
the test population. It is a classic measure of acute toxicity.
14. What does "toxicodynamics" refer to?
A. Movement of drugs in the economy
B. How a drug affects the body
C. How the body absorbs, distributes, metabolizes, and excretes drugs
D. The mechanical engineering of toxic substances
Answer: B