Bioequivalence and Bioavailability Forum

Hi ElMaestro & Silva,

❝ ❝ In a crossover study using only one sequence (RT for ex.) […]

This is not a crossover but a paired design.

❝ There is no sequence effect here because Sequence only has one level.

❝ Period and Treatment will have the same meaning;

Right.

❝ But are you sure this is a design you really want to use???

The only application of a paired design I’m aware of is to assess whether PK is linear by comparing AUC_0–τ (steady state = T) with AUC_0–∞ (single dose = R). Nobody would perform such a study as a crossover since the logistics would be terrible. ElMaestro correctly stated

❝ Period and Treatment will have the same meaning;

Hence, it should be unambiguously stated in the protocol that the model assumes (!) no period effect, i.e., the difference is related solely to the treatment. Contrary to a crossover where period effects mean out (unless sequences are extremely unbalanced) in a paired design great care must be taken to avoid a true period effect – which would confound the treatment effect.
Stupid example: No air conditioning in the clinics and a heat wave during SD.

@Silva: Is this was you are planning?