Effects of polymers on the crystallinity of nanonized meloxicam during a co-grinding process

Particle size reduction to the submicron region in a grinding process demands a high energy input. This grinding energy requirement can be reduced by means of a suitable additive, e.g. polymer, and performing a co-grinding process. Although these excipients promote attainment of the nanoparticle size range, they can also decrease the crystallinity of the active pharmaceutical ingredient. Different types of polymers have different abilities to amorphize the active material. To demonstrate the amorphization effects of different polymers, meloxicam (MX) as a model drug was subjected to co-grinding in the presence of one or other of four different polymers (PEG 6000, PEG 20,000, PVP C30 and PVP K25) and the products were investigated by XRPD, FT-IR and SEM. Although the PEG materials slightly melted and covered the MX particles during the grinding, they did not cause any changes in crystallinity. The PVP polymers softened and covered the MX particles, but drastically reduced the crystallinity of the drug. FT-IR revealed a weak secondary bonding between MX and the PVP polymer chain.