Bioequivalence and Bioavailability Forum • RTR|TRT

RTR|TRT [RSABE / ABEL]

posted by Helmut – Vienna, Austria, 2014-10-22 18:36 (3856 d 19:54 ago) – Posting: # 13769
Views: 14,520

Hi Felipe,

I oppose our Master when he wrote:

Thus it isn't necessary to have two administrations of Test within each subject.

Correct, if you have only CV_WR needed for scaling in mind. But – if CV_WR<30% – FDA’s mixed-effects code fails sometimes in partial replicated studies (TRR|RRT|RTR) since the model is over-specifed. Either parameterize the covariance structure as FA0(1) – instead of TYPE=FA0(2) given in the guidance – or perform a fully replicated three-period design (RTR|TRT). This design seemingly converges always and additionally gives you information about your product.

Sample sizes for FDA’s RSABE (T/R 90%, 80% power):

CV%          20  30  40  50  80

───────────────────────────────

RTRT|TRTR    32  24  24  22  28

TRR|RRT|RTR  30  45  33  30  42

RTR|TRT      28  46  38  34  44

I would not recommend a four-period study (more blood draws / subjects, higher drop-out rate).

—
Dif-tor heh smusma 🖖🏼 Довге життя Україна!
Helmut Schütz

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Complete thread:

3x3 or 2x4? felipeberlinski 2014-10-22 14:20
- 3x3 or 2x4? ElMaestro 2014-10-22 14:42
  - 3x3 or 2x4? nobody 2014-10-22 15:06
    - 3x3 or 2x4? felipeberlinski 2014-10-22 15:36
      - 3x3 or 2x4? nobody 2014-10-22 15:41
      - 2x3x3 or 2x2x3 or 2x2x4? d_labes 2014-10-22 16:12
        
        2x3x3 or 2x2x3 or 2x2x4? MGR 2015-04-08 13:35
        
        Sample size for scABE in SAS? d_labes 2015-04-08 16:06
        Re-inventing the wheel Helmut 2015-04-08 16:19
- RTR|TRTHelmut 2014-10-22 16:36
- 3x3 or 2x4? Mauricio Sampaio 2014-10-28 12:12