Bioequivalence and Bioavailability Forum • Lin-up/log-down trapezoidal example

Lin-up/log-down trapezoidal example [NCA / SHAM]

posted by yjlee168 – Kaohsiung, Taiwan, 2013-05-25 21:45 (4361 d 13:09 ago) – Posting: # 10658
Views: 19,311

Dear Helmut,

I think the differences at elimination phase between linear and log-down may results from the degree of concavity ([C1-C2]) within a know time interval (t2-t1). I also did a simple test with two different scenarios:

** if t2-t1 = 12 h; C1 = 4.1, C2 =1.1 (the curve is more concave between t1 and t2)



  AUC_(t1-t2) linear = 31.2; log-down = 27.362 (log-down should be more accurate in this situation)

  

** if t2-t1 = 12 h; C1 = 4.1, C2 =4.05 (the curve is less concave between t1 and t2; AUC_(t1-t2) should be more close to real trapezoidal shape)



  AUC_(t1-t2) linear = 48.9; log-down = 48.9 (before truncated was 48.89939) (the linear is supposed to be better than log-down; however log-down still keeps the accuracy as good as linear and almost as same as the linear.)

Therefore, you're right about log-down method. The log-down can be set as default method for AUC calculation safely, accurately and reliably.

—
All the best,
-- Yung-jin Lee
bear v2.9.2:- created by Hsin-ya Lee & Yung-jin Lee
Kaohsiung, Taiwan https://www.pkpd168.com/bear
Download link (updated) -> here

Complete thread:

handling of missing data gracehung 2013-05-20 07:35
- Lin-up/log-down trapezoidal avoids most trouble Helmut 2013-05-20 14:22
  - Lin-up/log-down trapezoidal avoids most trouble yjlee168 2013-05-22 08:25
    - Multiple peaks: fallback to linear trapezoidal Helmut 2013-05-22 20:25
      - Multiple peaks: fallback to linear trapezoidal yjlee168 2013-05-22 21:57
        
        No interpolation Helmut 2013-05-22 23:25
        
        No interpolation yjlee168 2013-05-23 11:43
        
        Spaghetti & other pasta Helmut 2013-05-23 15:15
        
        Spaghetti & other pasta yjlee168 2013-05-23 20:47
        
        Spaghetti & other pasta Helmut 2013-05-23 21:29
        
        Spaghetti & other pasta yjlee168 2013-05-23 22:46
        
        Spaghetti & other pasta Helmut 2013-05-24 01:24
        
        Spaghetti & other pasta yjlee168 2013-05-24 09:17
        
        No interpolation Ken Peh 2013-05-30 19:55
        
        Different algos! Helmut 2013-05-30 22:38
        
        Different algos! Ken Peh 2013-06-03 17:52
        
        Calculate what? Helmut 2013-06-03 18:11
    - Lin-up/log-down trapezoidal example Helmut 2013-05-25 15:09
      - Lin-up/log-down trapezoidal exampleyjlee168 2013-05-25 19:45
- handling of missing data Ohlbe 2013-05-20 21:45
  - Sorry Helmut 2013-05-21 13:53
    - Sorry gracehung 2013-05-23 01:06
      - Uncertain time point Helmut 2013-05-23 01:35