According to the United States Pharmacopeia (USP) monograph, the assay limit is 98.0% to 102.0%. This range represents the acceptable limits for the potency of a drug substance or drug product when tested using a USP-specified assay method.
Here's a breakdown of what this means:
- USP Monograph: A USP monograph is a legally recognized standard that defines the requirements for identity, strength, quality, purity, packaging, and labeling of drug substances and drug products.
- Assay: An assay is a quantitative analytical procedure used to determine the amount of a specific substance in a sample. In the pharmaceutical context, it's used to determine the potency or concentration of the active pharmaceutical ingredient (API).
- Assay Limit (98.0% - 102.0%): This percentage range indicates that the API content in the tested sample must fall within 98.0% and 102.0% of the labeled claim. This is an acceptance criterion designed to ensure that the drug product contains the appropriate amount of the active ingredient for efficacy and safety. If the assay result falls outside this range, the batch typically fails to meet USP standards.
Example:
Let's say a tablet is labeled to contain 100 mg of a drug substance. To meet the USP assay requirements, the actual amount of the drug substance in the tablet, as determined by the USP assay method, should be between 98.0 mg and 102.0 mg.
Significance of the USP Assay Limit:
The USP assay limit plays a crucial role in:
- Ensuring drug product quality: By setting a defined range, it guarantees that the drug product contains the correct amount of API.
- Maintaining therapeutic efficacy: It ensures that patients receive the intended dose of the drug substance, leading to the desired therapeutic effect.
- Guaranteeing patient safety: It prevents situations where the drug product contains too little or too much of the API, potentially leading to under-treatment or adverse effects.
- Providing regulatory compliance: Meeting the USP assay limit is often a regulatory requirement for pharmaceutical companies.
