Formation of fine drug particle by cogrinding with cyclodextrins. Part II. The influence of moisture condition during cogrinding process on fine particle formation.

The purpose of this study was to investigate the effect of moisture condition during cogrinding process on fine drug particle formation. Cogrinding of cyclodextrins (CDs) and pranlukast (PRK) hemihydrate was performed in various moisture conditions at a mixing molar ratio of 2:1 (CDs:PRK) and the formation of PRK submicron particle was investigated. The moisture content in the cogrinding process significantly affected the fine particle formation. More than 90% of pranlukast loaded transformed to submicron particles when coground with alpha-CD, beta-CD or gamma-CD containing the specific amount of water for each CD system. Fine particle formation of PRK was considered as a particular phenomenon to cyclodextrins, since the submicron particles could not be formed when D-mannitol, lactose or microcrystalline cellulose (MCC) was used as a cogrinding additive. Moreover, the appearance and disappearance of fine particle formation was found to be reversible depending on the existence of water during the grinding process.