Bioequivalence and Bioavailability Forum

Salam Mohamed,

❝ I want to know how to calculate the T1 and T2 of schuirmann test for 2*2 crossover bioequivalence study.... I found this equation, i want to know whether it is correct or wrong?.

Correct for a parallel design, wrong for a 2×2×2 crossover. Use these ones:

where Y_T and Y_R are the geometric least squares (aka marginal, adjusted) means of T and R, θ₁ and θ₂ the lower und upper limits of the acceptance range, σ_w the √MSE from ANOVA, and n₁, n₂ the number of subjects / sequence.

BTW, consider reading the original paper* instead of trusting in what you find on the internet (including this site, of course).

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• Schuirmann DJ. A comparison of the Two One-Sided Tests Procedure and the Power Approach for Assessing the Equivalence of Average Bioavailability. J Pharmacokin Biopharm. 1987;15(6):657–80. doi:10.1007/BF01068419.