{"id":12381,"date":"2026-08-21T11:07:31","date_gmt":"2026-08-21T11:07:31","guid":{"rendered":"https:\/\/www.medkart.in\/blog\/?p=12381"},"modified":"2026-09-08T11:15:12","modified_gmt":"2026-09-08T11:15:12","slug":"what-is-bioequivalence-generic-medicine-testing","status":"publish","type":"post","link":"https:\/\/www.medkart.in\/blog\/what-is-bioequivalence-generic-medicine-testing\/","title":{"rendered":"Bioequivalence: How Generic Medicines Are Tested and Approved in India"},"content":{"rendered":"

Bioequivalence is the test that decides whether a generic medicine can stand in for the product it copies. It compares how much of the active ingredient reaches the bloodstream, and how fast.<\/span><\/p>\n

Generic medicines are approved on that comparison rather than on fresh trials in patients. The rules governing the comparison are set by regulators, and they differ in detail between countries.<\/span><\/p>\n

What is bioequivalence?\u00a0<\/b><\/h2>\n

Bioequivalence is a comparison between two formulations of the same active ingredient. India’s New Drugs and Clinical Trials Rules, 2019<\/span>[<\/span>1<\/span><\/a>]<\/span><\/sup> define a bioequivalence study as one establishing the absence of a statistically significant difference in the rate and extent of absorption. That comparison is made against a reference formulation with the same active ingredient.<\/span><\/p>\n

The World Health Organization<\/span>[<\/span>2<\/span><\/a>]<\/span><\/sup> frames it as two products being bioequivalent when their bioavailabilities are similar to such a degree that the same effects can be expected from both. It treats Cmax and tmax as the measures of rate, and the area under the curve as the measure of extent.<\/span><\/p>\n

The US FDA<\/span>[<\/span>3<\/span><\/a>]<\/span><\/sup> states the same idea more plainly. A generic drug is bioequivalent when it delivers the same amount of active ingredient at the same rate and to the same extent as the brand-name drug.<\/span><\/p>\n

What is a generic medicine?\u00a0<\/b><\/h2>\n

A generic medicine is a copy of a brand-name medicine that has already been approved. The FDA’s summary of generic drug facts<\/span>[<\/span>4<\/span><\/a>]<\/span><\/sup> states that a generic must have the same active ingredient, strength, dosage form and route of administration as the brand-name drug.<\/span><\/p>\n

It must also be made under the same strict standards, carry the same label with certain exceptions, and be bioequivalent to the brand-name medicine. The FDA states that approved generics work in the same way and provide the same clinical benefit and risks as their brand-name counterparts.<\/span><\/p>\n

Those statements describe the United States regulatory standard. An India-specific regulatory source is needed before making the same claim about a particular Indian product.<\/span><\/p>\n

What does a bioequivalence study measure?\u00a0<\/b><\/h2>\n

A bioequivalence study measures the active ingredient in the blood over time. WHO names the measures that matter and the range the result has to fall inside.<\/span><\/p>\n\n\n\n\n\n\n\n
Measure<\/b><\/td>\nWhat it shows<\/b><\/td>\n<\/tr>\n
Cmax<\/b><\/td>\nThe highest concentration the active ingredient reaches. WHO treats this as one of the two measures of the rate of absorption.<\/span><\/td>\n<\/tr>\n
tmax<\/b><\/td>\nThe time at which that highest concentration is reached. It is the second measure of rate.<\/span><\/td>\n<\/tr>\n
Area under the curve<\/b><\/td>\nThe total exposure over time, which WHO treats as the measure of the extent of absorption.<\/span><\/td>\n<\/tr>\n
90% confidence interval<\/b><\/td>\nThe statistical result. WHO states the interval for the geometric mean ratio should normally fall within 80 to 125% for log-transformed data.<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

The underlying quantity is bioavailability. The New Drugs and Clinical Trials Rules define a bioavailability study as one assessing the rate and extent to which a drug is absorbed from a formulation. The definition covers the drug becoming available in the systemic circulation, or at the site of action.<\/span><\/p>\n

Those acceptance limits are the WHO figures, and an Indian regulatory source setting the same numbers was not available for this article. WHO states that the primary concern in a bioequivalence assessment is to limit the risk of a false declaration of equivalence.<\/span><\/p>\n

How is a bioequivalence study run?\u00a0<\/b><\/h2>\n

The study compares a test product against a comparator. WHO defines the comparator product as the one the generic is intended to be interchangeable with in clinical practice, and normally that is the innovator product.<\/span><\/p>\n

WHO states that bioequivalence studies should generally be performed with healthy volunteers rather than with patients. The FDA’s description of an abbreviated new drug application<\/span>[<\/span>5<\/span><\/a>]<\/span><\/sup> says much the same, measuring how long the generic takes to reach the bloodstream in healthy volunteers.<\/span><\/p>\n

WHO lists four ways of assessing equivalence:<\/span><\/p>\n