Effect of compression on non-isothermal crystallization behaviour of amorphous indomethacin.

PURPOSE: To evaluate the effect of tablet compression on the physical stability of amorphous indomethacin. METHODS: The amorphous indomethacin generated by melt cooling, rapid (5°C/min) or slow (0.2°C/min) cooling, was evaluated by PXRD, mDSC and FTIR analysis. Non-isothermal crystallisation behaviour was assessed using mDSC and any structural changes with compression were monitored by FTIR. Amorphous indomethacin was compressed in a DSC pan using a custom made die cavity-punch setup and further analysed in the primary container to minimize stress due to sample transfer and preparation. RESULTS: Compression of amorphous indomethacin induced and increased the extent of crystallisation upon heating. DSC results revealed that amorphous indomethacin generated by rapid cooling is more prone to compression induced crystallisation than the slowly cooled one. Onset temperature for crystallisation (T(c)) of uncompressed slowly and rapidly cooled samples are 121.4 and 124°C and after compression T(c) decreased to ca 109 and ca 113°C, respectively. Compression of non-aged samples led to higher extent of crystallisation predominantly into γ-form. Aging followed by compression led to crystallisation of mainly the α-form. CONCLUSIONS: Compression affects the physical stability of amorphous indomethacin. Structural changes originated from tablet compression should be duly investigated for the stable amorphous formulation development.

Can compression induce demixing in amorphous solid dispersions? A case study of naproxen-PVP K25.

The aim of this work is to investigate the effect of compression on miscibility of naproxen (NAP)-PVP K25 solid dispersions. Solid dispersions with diverse drug/polymer compositions were compressed at various forces for uniform dwell time. Miscibility assessments were performed using mDSC, and the effect of compression on the specific interactions of NAP and PVP K25 was investigated by FTIR. The 20% (w/w) naproxen containing solid dispersion showed a single T(g) before and after compression. FTIR analysis showed the unchanged profile of this system upon compression. On the other hand, the miscibility in the compositions with 30% and 40% (w/w) naproxen is markedly affected by compression. Compression pressures from beyond 565.05 MPa induced apparent amorphous-amorphous phase separation as indicated by two characteristic T(g)s in DSC and altered IR spectral profile. The highly ductile nature of PVP promotes plastic deformation upon compression induced by the rotation of the PVP backbone with the transition of dihedral angles from low to high energy state. Segmental rotation can also be an outcome of plastic deformation that often leads to increase in structural temperature. This can have influence on miscibility resulting from weakening and/or disruption of intermolecular hydrogen bonding between drug and polymer upon compression.

Trends in pharmaceutical taste masking technologies: a patent review.

According to the year 2003 survey of pediatricians by the American Association of Pediatrics, unpleasant taste was the biggest barrier for completing treatment in pediatrics. The field of taste masking of active pharmaceutical ingredients (API) has been continuously evolving with varied technologies and new excipients. The article reviews the trends in taste masking technologies by studying the current state of the art patent database for the span of year 1997 to 2007. The worldwide database of European patent office (http://ep.espacenet.com) was employed to collect the patents and patent applications. It also discusses the possible reasons for the change of preferences in the taste masking technologies with time. The prime factors critical to the selection of an optimal taste masking technique such as the extent of drug bitterness, solubility, particle characteristics, dosage form and dose are briefly discussed.