Influence of crystal habit on the compression and densification mechanism of ibuprofen

Ibuprofen was recrystallized from several solvents by two different methods: addition of a non-solvent to a drug solution and cooling of a drug solution. Four samples, characterized by different crystal habit, were selected: sample A, sample E andsample T, recrystallizedrespectively from acetone, ethanol andTHF by addition of water as non-solvent andsample M recrystallized from methanol by temperature decrease. By SEM analysis, sample were characterized with the respect of their crystal habit, mean particle diameter and elongation ratio. Sample A appears stick-shaped, sample E acicular with lamellar characteristics, samples T and M polyhedral. DSC and X-ray diffraction studies permit to exclude a polymorphic modification of ibuprofen during crystallization. For all samples micromeritics properties, densification behaviour and compression ability was analysed. Sample M shows a higher densification tendency, evidenciated by its higher apparent and tapped particle density. The ability to densificate is also pointed out by D0’ value of Heckel’s plot, which indicate the rearrangement of original particles at the initial stage of compression. This fact is relatedto the crystal habit of sample M, which is characterizedby strongly smoothed coins. The increase in powder bed porosity permits a particle–particle interaction of greater extent during the subsequent stage of compression, which allows higher tabletability andcompressibility.