Video narration
Investigators compare pharmacokinetic endpoints, commonly AUC and Cmax, between the test and reference products. The comparison is expressed as a test-to-reference exposure ratio, using an appropriate statistical analysis. Under a commonly taught regulatory standard, the 90 percent confidence interval around the geometric-mean ratio for selected endpoints must lie within 80.00 percent to 125.00 percent. That does not mean an individual person's concentration is allowed to differ by 80 percent. It does not mean the test product simply has to deliver between 80 and 125 percent of the dose. The range applies to the confidence interval for a statistical exposure ratio, under the applicable study design. And passing that comparison does not make two products chemically identical. They can differ in inactive ingredients, manufacturing details, and the exact shape of their concentration-time curves. Nor does this single framework settle interchangeability in every clinical circumstance; some products require additional endpoints or different regulatory approaches. So, do equal-strength tablets guarantee equal exposure? No. Bioavailability asks what systemic exposure one product produces. Bioequivalence asks whether a test product and reference product produce sufficiently similar exposure.