Bioequivalence and Bioavailability Forum • tmax ≠ Cmax 🙂

tmax ≠ Cmax 🙂 [NCA / SHAM]

posted by BEQool – 2023-06-27 20:25 (678 d 15:13 ago) – Posting: # 23631
Views: 3,201

❝ ❝ ❝ Tmax: Time of maximum observed concentration. For non-steady-state data, the entire curve is considered. If the maximum observed concentration is not unique, then the first maximum is used

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❝ Yes but the Cmax was defined accordingly:

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❝ Cmax: Maximum observed concentration, occurring at time Tmax, as defined above.

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❝ When reading this, we can easily think that the software would take the first peak as Cmax.

Hello Imph,

if I am not mistaken, I think that you may be mixing peaks with maximums (maximum ≠ peak)?
You may have multiple peaks in a profile but normally (almost always) just one maximum concentration and this one maximum concentration defines Tmax.
Just in extreme rare cases when you have two identical maximum concentrations (not just two peaks but two peaks with the same highest concentration) at different sampling time points, the software (WinNonlin) uses first highest concentration (Cmax) sampling point as Tmax.

Complete thread:

concentration-time profile with two peaks or more Imph 2023-06-27 13:06 [NCA / SHAM]
- concentration-time profile with two peaks or more dshah 2023-06-27 13:13
  - concentration-time profile with two peaks or more Imph 2023-06-27 13:26
    - What does ‘max’ in Cmax mean? Helmut 2023-06-27 13:44
      - What does ‘max’ in Cmax mean? Imph 2023-06-27 15:18
        
        Which software? Helmut 2023-06-27 15:24
        
        Which software? Imph 2023-06-27 16:56
        
        tmax ≠ Cmax 🙂 Helmut 2023-06-27 17:03
        
        tmax ≠ Cmax 🙂 Imph 2023-06-27 17:33
        
        tmax ≠ Cmax 🙂BEQool 2023-06-27 18:25