Consideration of individual bioequivalence.

Area of Science:

• Pharmacokinetics and Biopharmaceutics
• Statistical Methods in Clinical Trials
• Drug Formulation and Generic Substitution

Background:

• Current bioequivalence assessments focus on average responses between drug formulations, not individual patient responses.
• Average bioequivalence does not guarantee consistent individual patient outcomes when switching formulations, such as to generic alternatives.
• A need exists for a statistically sound method to ensure individual bioequivalence for patient safety and therapeutic consistency.

Purpose of the Study:

• To propose and validate a novel statistical procedure for assessing individual bioequivalence between drug formulations.
• To introduce the Test of Individual Equivalence Ratios (TIER) as a method to ensure individual patient responses are similar across formulations.
• To provide a statistically valid alternative to existing, less rigorous methods for assessing bioequivalence at the individual level.

Main Methods:

• Development of the Test of Individual Equivalence Ratios (TIER) decision rule.
• TIER requires specifying the minimum acceptable proportion of subjects exhibiting bioequivalence.
• Calculation of lower bounds (one-sided confidence intervals) for the proportion of bioequivalent subjects.

Main Results:

• The TIER procedure offers a statistically valid framework for assessing individual bioequivalence.
• TIER addresses limitations of average bioequivalence by focusing on individual subject responses.
• The method is partly inspired by the FDA's 75/75 Rule but provides a statistically rigorous approach.

Conclusions:

• The TIER procedure provides a statistically valid and reliable method for assessing individual bioequivalence.
• This approach enhances assurance for patients switching between drug formulations, including generic substitutions.
• TIER offers a superior alternative to existing methods by focusing on individual patient outcomes and statistical validity.