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jag009 ★★★ NJ, 2013-08-23 18:46 (4281 d 22:49 ago) Posting: # 11339 Views: 10,433 |
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Hi everyone, Just a random thought about another advantage of a 4-period full replicate (TTRR) study over a 3-period partial replicate (TRR) study design besides 1) reducing the sample size and 2) elucidating the ISCV of the test. If a previous partial replicate study (TRR) showed that 1) Ref ISCV was significantly > 30% (lets say 50-60%) 2) the (Ref1/Ref2) ratios for PK were significant (ie: 15% or higher), wouldn't a 4-period full rep (TTRR) study be the preferred choice if one assumes that the test could show the same behavior as the reference (meaing T1/T2 ratio > 15%)? In such scenario you are more or less stabilizing both the test and reference by giving each 2x. I am just wondering if this would help in terms of meeting the 80-125% ratio requirement. I apologize for the crazy writing but I was doing something else while this stupid idea popped up... Thanks John Edit: Category changed. [Helmut] |
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ElMaestro ★★★ Denmark, 2013-08-24 19:35 (4280 d 21:59 ago) @ jag009 Posting: # 11340 Views: 9,224 |
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Hello John, ❝ If a previous partial replicate study (TRR) showed that 1) Ref ISCV was significantly > 30% (lets say 50-60%) 2) the (Ref1/Ref2) ratios for PK were significant (ie: 15% or higher), wouldn't a 4-period full rep (TTRR) study be the preferred choice if one assumes that the test could show the same behavior as the reference (meaing T1/T2 ratio > 15%)? In such scenario you are more or less stabilizing both the test and reference by giving each 2x. I was dropped on the floor head-first at birth and furthermore suffered severe hypoxia due to the umbilical chord looping 17 times around my neck. According to my aunt it was a masterpiece of crocheting. Therefore, my cerebral development has been suffering severely and therefore I am afraid I have very little idea of what you actually mean. You may indeed have a point, but could you perhaps elaborate a little? Terima kasih  — Pass or fail! ElMaestro |
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Dr_Dan ★★ Germany, 2013-08-26 11:16 (4279 d 06:18 ago) @ jag009 Posting: # 11342 Views: 9,203 |
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Hi John it's a question of sample size and number of comparisons between test and reference. You have to increase the number of subjects in a partial replicate if you want to have the same number of comparisons of a full replicate design. If you have an incomplete replicate design (TRT vs RTR) then you have the advantage of only three periods, ISCV of test and reference and the full number of comparisons. Do you agree? Kind regards Dan — Kind regards and have a nice day Dr_Dan |
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jag009 ★★★ NJ, 2013-08-26 17:42 (4278 d 23:52 ago) @ Dr_Dan Posting: # 11347 Views: 9,139 |
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Hi Dr Dan and ElMaestro, Like I said I wasn't really thinking when I wrote that post. Anyhow here is the issue:
I looked at study #2 in terms of Reference arm 1 and Reference 2. Did a comparison between the two (R1/R2), the AUC ratios were 0.85% (Cmax ~ 91%). I did the same thing for study #1. R1/R2 ratios for AUC and Cmax were 98% and 96%. I guess it's just the nature of the HVD but I am kind of surprise by how different the Reference behaved that's all. Would sample size help in this regard or even with an increase in sample size the outcome is still trivial? John |
Ing. Helmut Schütz