AAPS PharmSciTech

, Volume 19, Issue 7, pp 2787–2800 | Cite as

Particle Size Distribution Equivalency as Novel Predictors for Bioequivalence

  • Pratak Ngeacharernkul
  • Stephen D. Stamatis
  • Lee E. KirschEmail author
Research Article Theme: Team Science and Education for Pharmaceuticals: the NIPTE Model
Part of the following topical collections:
  1. Theme: Team Science and Education for Pharmaceuticals: the NIPTE Model


The use of particle size distribution (PSD) similarity metrics and the development and incorporation of drug release predictions based on PSD properties into PBPK models for various drug administration routes may provide a holistic approach for evaluating the effect of PSD differences on in vitro drug release and bioavailability of disperse systems. The objectives of this study were to provide a rational approach for evaluating the utility of in vitro PSD comparators for predicting bioequivalence for subcutaneously administered test and reference drug emulsions. Two types of in vitro comparators for test and reference emulsion products were evaluated: PSD characterization comparators (overlap metrics, median, and span ratios) and release profile comparators (f2 and various fractional time ratios). A subcutaneous-input PBPK disposition model was developed to simulate blood concentration-time profiles of reference and test emulsion products and pharmacokinetic responses (e.g., AUC, Cmax, and Tmax) were used to determine bioequivalence. A pool of 10,440 pairs of test and reference products was simulated using Monte Carlo experiments. The PSD and release profile comparators were correlated to pass/fail bioequivalence metrics using logistical regression. Based on the use of single in vitro comparators, the f2 method was the best predictor of bioequivalence prediction. The use of combinations of f2 and PSD overlap comparators (e.g., OVL or PROB) improved bioequivalence prediction to about 90%. Simulation procedures used in this study demonstrated a process for developing reliable in vitro BE predictors.


bioequivalence particle size distribution modeling and simulation emulsion subcutaneous administration PBPK 


Funding Information

The authors gratefully acknowledge funding from the US‐FDA and the National Institute of Pharmaceutical Technology and Education through contract #5U01FD004275‐03; NIPTE‐2013‐002.


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Copyright information

© American Association of Pharmaceutical Scientists 2018

Authors and Affiliations

  • Pratak Ngeacharernkul
    • 1
  • Stephen D. Stamatis
    • 1
    • 2
  • Lee E. Kirsch
    • 1
    Email author
  1. 1.Division of PharmaceuticsThe University of IowaIowa CityUSA
  2. 2.Lilly Research LaboratoriesEli Lilly and CompanyIndianapolisUSA

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