content uniformity

Content uniformity checks that individual dosage units each carry close to the same amount of active drug, rather than only that the average is right. Imagine a box of supposedly identical chocolates: the average filling might be fine while a few are nearly empty and a few overfilled — content uniformity catches that unit-to-unit scatter.

Several individual units (typically ten, with up to thirty assayed if needed) are assayed one at a time for actual drug content. The results are combined into an acceptance value that reflects both how far the mean sits from label claim and how spread out the individual values are. A small acceptance value passes; too much variability or a unit far outside limits fails.

Content uniformity is the standard way to demonstrate uniformity of dosage units for low-dose products, where even small absolute variation is a large relative variation, and for any product where weight alone is not a reliable surrogate for content. For higher-dose units that are well-blended, the simpler weight variation method may be permitted instead.