The concept describes the maximum level of a pharmaceutical impurity or excipient that can be present in a drug product without posing a significant safety risk to patients who take the medication daily over their lifetime. This value, usually expressed in micrograms per day, is established based on available toxicological data and safety factors. For instance, if a substance is found to cause adverse effects in animal studies at a certain dose, the value is calculated by dividing that dose by safety factors to account for interspecies differences and individual human variability.
Establishing this limit is crucial in the drug development and manufacturing process. It ensures patient safety by controlling the amount of potentially harmful substances to which they are exposed. Historically, the setting of such limits has evolved from empirical observations to sophisticated risk assessment methodologies. Benefits include improved drug quality, reduced risk of adverse drug reactions, and greater confidence in the safety profile of medications.
