Minimum Interfacial Bonding Strength for Bilayer Tablets Determined Using a Survival Test

Shao Yu Chang, Changquan Calvin Sun

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Purpose: To identify the minimum interfacial bonding strength (IBS) required for bilayer tablets to sustain the stresses experienced during manufacturing, transportation, and handling. Methods: Bilayer tablets of a number of formulations with systematically varied IBS were prepared on a materials testing macine. Five bilayer tablets with the same IBS were repeatedly dropped at a fixed height in a friabilator and integrity of the interface was periodically examined. The number of tablets free from observable defects at the interface was plotted as a function of the number of drops. The IBS for all five tablets to remain intact after 1000 drops was taken as the minimum IBS for a given formulation. Results: The minimum IBS depends on both layer composition and tablet size. For bilayer tablets made with more brittle materials or a larger size, a higher minimum IBS is required to pass the survival test. The incorporation of HPMC leads to a lower minimum IBS. An IBS of 0.26 MPa is sufficient for all bilayer tablet formulations and sizes to pass the survival test in this work. Conclusions: A minimum IBS of 0.26 MPa is recommended as a tentative criterion for bilayer tablets of most materials to avoid quality issues arising from inadequate IBS.

Original languageEnglish (US)
Article number139
JournalPharmaceutical research
Issue number10
StatePublished - Oct 1 2019

Bibliographical note

Funding Information:
S-Y. Chang was partially supported by a David and Marilyn Grant Fellowship in Physical Pharmacy (2017–2018), Department of Pharmaceutics, University of Minnesota.

Publisher Copyright:
© 2019, Springer Science+Business Media, LLC, part of Springer Nature.


  • HPMC
  • lactose
  • microcrystalline cellulose
  • minimum interfacial bonding strength
  • survival test


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