Question

The ‘Up‐and‐Down’ method for a projected LD50 determination is described in the…..

• A. OECD Guideline 401
• B. OECD Guideline 420
• C. OECD Guideline 423
• D. OECD Guideline 425

Answer 1

The Correct Option is D

The question revolves around the determination of LD50 using specific OECD guidelines. LD50, which represents the lethal dose required to kill 50% of a test population, is a critical measure in toxicology. Among the various guidelines offered by the Organisation for Economic Co-operation and Development (OECD) for acute toxicity testing, the correct method for determining the projected LD50 using an 'Up-and-Down' approach is detailed in OECD Guideline 425.

1. Understanding OECD Guidelines:
   • OECD Guideline 401: This guideline used to describe a conventional, now-deleted method for acute oral toxicity testing, involving fixed doses.
   • OECD Guideline 420: This is the Fixed Dose Procedure, which estimates a toxic dose but does not specifically use the 'Up-and-Down' method.
   • OECD Guideline 423: The Acute Toxic Class method, not specifically focused on 'Up-and-Down' method but for classifying substances in toxicity categories.
   • OECD Guideline 425: This guideline specifically addresses the 'Up-and-Down' Procedure for determining LD50. It involves dosing animals sequentially, based on the outcome of the previous animal's response, allowing for efficiency and reduction in the number of test animals.
2. Justifying the Correct Answer:
   • The 'Up-and-Down' method is explicitly covered in OECD Guideline 425. This approach minimizes the number of animals used while determining an approximate LD50. It involves dosing individual animals sequentially, which allows for a statistical estimate of the LD50.
   • OECD Guidelines 401, 420, and 423 do not employ the 'Up-and-Down' method, making them incorrect choices for this specific inquiry.

Thus, the correct answer is OECD Guideline 425.