Bioequivalence and Bioavailability Forum

Hi Mittyri,

❝ Our results for Cmax were:

❝ 90%CI=[0.847; 1.134]

❝ CV=38%, PE=0.98, N=36

❝ Does it mean that with a probability 90% the real GMR of Cmax lies between 0.847 and 1.134? Does it mean that the mentioned probability normally distributed in this interval?

It means that if the assumptions are correct (the residual is normal) and if the true GMR is 0.98 and if the CV is 38% then there is a 90% chance that the estimated GMR will be between your observed limits when you conduct a study on 36 subjects.

❝ We're planning to perform the second study with the same API, but another strength (100mg).

❝ Which GMR would you propose? 0.98% (optimistic from previous study)? 0.95% (standard)?

If you can afford it, it might be a good idea to go even a little lower. After all, this is a new formulation, right?
There are no rules, and you'll be going by gut feeling. If you intend the next study to be pivotal then the choice of GMR guess should reflect a ton of factors including biology, dissolution, gut feeling, Saturn's moons, your biorhythms, personal horoscope (you've gotta ask yourself one question: "Do I feel lucky?" Well, do ya, punk?) etc but not your management's desire to save money.