OT: keep TTT! [PK / PD]
Dear Yung-jin,
I was giving a workshop and had limited spare time…
Yes. But still slightly better than R²adj alone – the only one available in commercial software.
Please no! Contrary to R²adj TTT is based on PK-grounds. I would not call it model-dependent. OK, it is based on a one-compartment model but the estimation of λz is within the boundaries of NCA, IMHO. For multiple distribution / elimination phases it is the responsibility of the user to select the last loglinear phase visually.
I think that you should keep it. If we find a reasonable automatic method for >1 compartment you can add it.
Anyhow, I’m not overly optimistic yet – especially if at least one of the following conditions applies:
I started a new thread over there.
❝ […] I just wondered why you did not respond at that moment.
I was giving a workshop and had limited spare time…
❝ As illustrated, TTT rule may cause extreme bias for λz estimation when the study drug exhibits more than one-compartment PK model, i.e., when it has more than one exponential terms mathematically.
Yes. But still slightly better than R²adj alone – the only one available in commercial software.
❝ Should I consider to remove TTT from bear first since it is a model-dependent approach?
Please no! Contrary to R²adj TTT is based on PK-grounds. I would not call it model-dependent. OK, it is based on a one-compartment model but the estimation of λz is within the boundaries of NCA, IMHO. For multiple distribution / elimination phases it is the responsibility of the user to select the last loglinear phase visually.
❝ And then we can add it back again when we have clear picture about it.
I think that you should keep it. If we find a reasonable automatic method for >1 compartment you can add it.
Anyhow, I’m not overly optimistic yet – especially if at least one of the following conditions applies:
- Noisy data.
- Limited samples, especially in the area of the ‘breakpoint’.
- No pronounced difference in rate constants (rule of thumb: ratios ≤5 are difficult to detect).
- Large differences in volumes of distribution. Might be only of theoretical interest because one of the phases will not be apparent unless the analytical method is very sensitive.
I started a new thread over there.
—
Dif-tor heh smusma 🖖🏼 Довге життя Україна!
Helmut Schütz
The quality of responses received is directly proportional to the quality of the question asked. 🚮
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Dif-tor heh smusma 🖖🏼 Довге життя Україна!
Helmut Schütz
The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes
Complete thread:
- 1 compartment model with lag time jag009 2013-07-17 15:58 [PK / PD]
- solve for k01? Helmut 2013-07-17 16:08
- solve for k01? jag009 2013-07-17 16:19
- solve for k01? ElMaestro 2013-07-17 17:09
- no closed form Helmut 2013-07-17 23:01
- solve for k01? jag009 2013-07-17 16:19
- 1 compartment model with lag time yjlee168 2013-07-17 20:57
- Package-free solution ElMaestro 2013-07-17 21:53
- Package-free solution yjlee168 2013-07-17 22:11
- Package-free solution ElMaestro 2013-07-17 22:27
- Package-free solution yjlee168 2013-07-17 22:42
- Package-free solution ElMaestro 2013-07-17 22:27
- Package-free solution ElMaestro 2013-07-17 23:21
- A new R-King was born d_labes 2013-07-18 08:45
- Brent ElMaestro 2013-07-18 09:07
- A new R-King was born yjlee168 2013-07-18 10:21
- OT: TTT in bear Helmut 2013-07-18 20:28
- OT: TTT in bear yjlee168 2013-07-18 22:17
- OT: TTT subtleties d_labes 2013-07-19 09:47
- OT: TTT subtleties yjlee168 2013-07-20 19:44
- OT: beyond TTT? Helmut 2013-07-21 00:08
- OT: beyond TTT? yjlee168 2013-07-22 13:45
- OT: keep TTT!Helmut 2013-07-22 14:21
- OT: keep TTT! yjlee168 2013-07-22 23:42
- OT: EOD (here) Helmut 2013-07-23 01:06
- OT: keep TTT! yjlee168 2013-07-22 23:42
- OT: keep TTT!Helmut 2013-07-22 14:21
- OT: beyond TTT? yjlee168 2013-07-22 13:45
- OT: beyond TTT? Helmut 2013-07-21 00:08
- OT: TTT subtleties yjlee168 2013-07-20 19:44
- OT: TTT subtleties d_labes 2013-07-19 09:47
- OT: TTT in bear yjlee168 2013-07-18 22:17
- OT: TTT in bear Helmut 2013-07-18 20:28
- Package-free solution yjlee168 2013-07-18 10:27
- Thank you guys! jag009 2013-07-18 16:37
- Thank you guys! ElMaestro 2013-07-18 18:57
- Thank you guys! jag009 2013-07-19 20:40
- Thank you guys! ElMaestro 2013-07-18 18:57
- Thank you guys! jag009 2013-07-18 16:37
- A new R-King was born d_labes 2013-07-18 08:45
- Package-free solution yjlee168 2013-07-17 22:11
- solve for k01? Helmut 2013-07-17 16:08