Bioequivalence and Bioavailability Forum

Hi Jay,

❝ As mentioned in the EU GL, half of dosage interval may be considered. So if the label states once a day then AUC0-12 and AUC12-last may be considered.

Thank you for repeating what I already have written above.

Do you have an own opinion? I don’t see any pharmacokinetic justification for a cut-off of τ/2 but I’m always eager to learn something new. I can only speculate that the idea of the almighty oracle was to catch with the partial AUCs 50% of the AUC_0–τ but that doesn’t work:
kabs/kel  AUC0–τ/2/AUC0–τ  AUCτ/2–τ/AUC0–τ
  2.0         44.4%          55.6%
  1.0         38.0%          62.0%  ⇐ flip-flop
  0.5         34.3%          65.7%
Reminds me on an innovator (!) company which had the splendid idea to develop a new formulation of an antibiotic (doubled strength) in order to “double the time above the MIC”. When I talked about first-order processes and exponential functions and that therefore, this concept could never work they didn’t believe me at first. When I presented some plots they trashed the project. Lack of basic PK knowledge is abundant.