Effects of initial particle size on the tableting properties of L-lysine monohydrochloride dihydrate powder

Changquan Sun, David J.W. Grant

Research output: Contribution to journalArticlepeer-review

112 Scopus citations


L-lysine monohydrochloride (LMH) dihydrate was crystallized and the resulting powder was sieved to obtain various size fractions. The influence of other factors, such as crystallinity and crystal shape, was minimized by using the same batch of crystals. Compression of smaller particles at low compaction pressures resulted in tablets of greater porosity. The differences in porosity decreased with increasing compaction pressure. At the same compaction pressure, smaller particles formed tablets of greater tensile strength. However, fragmentation of the larger particles tended to equalize the particle size and reduce its influence. The differences were reduced for particles larger than 710 μm. For crystals of all size fractions, tensile strength increased with increasing compaction pressure. The tensile strength increased more rapidly for smaller crystals. Tensile strength decreased exponentially with increasing porosity for all fractions. The dependence of tensile strength on porosity is explained in term of tablet structure. Yield strength, calculated from 'out-of-die' Heckel analysis, increased with increasing particle size.

Original languageEnglish (US)
Pages (from-to)221-228
Number of pages8
JournalInternational journal of pharmaceutics
Issue number1-2
StatePublished - Mar 14 2001

Bibliographical note

Funding Information:
We thank the American Foundation for Pharmaceutical Education (AFPE) for a Pre-doctoral Fellowship for C.S. and Pfizer Central Research for partial financial support.


  • L-lysine monohydrochloride dihydrate
  • Particle fragmentation
  • Particle size
  • Tableting
  • Tensile strength
  • Yield strength


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