Effect of Humidity on The Formation and Stability of Acetaminophen-β-Cyclodextrin Inclusion Complexes

Abstract

The effect of humidities (75% RH and 100% RH) on the inclusion complex formation and crystallizing behavior of physical mixture and ground mixture of acetaminophen with α-cyclodextrin, β-cyclodextrin or microcrystalline cellulose at 30 °C were studied by DSC thermal analysis, X-ray diffractometer, IR spectrophotometer. The change of water content in the physical mixture and ground mixture when stored at 30 °C, 75% RH or 100% RH was determined. The results indicate that the inclusion complex formation and crystallizing behavior of these mixtures were dependent on the relative humidity and types of cyclodextrins. The physical mixture of acetaminophen and β-cyclodextrin stored at 30 °C and 100% RH was transformed to crystalline inclusion complex, but stored at 75% RH still exhibited a behavior of physical mixture. The ground mixture of acetaminophen and β-cyclodextrin was converted amorphous inclusion complex to crystalline inclusion complex whether stored at 75% RH or 100% RH. However, physical mixture and ground mixture of acetaminophen and α-cyclodextrin or microcrysatlline cellulose when stored at 75% RH or 100% RH belonged to a crystalline physical mixture.