Micronization of atorvastatin calcium by antisolvent precipitation process

Amorphous atorvastatin calcium (AC) ultrafine powder has been successfully prepared by antisolvent precipitation and spray drying process, in which hydroxypropyl methylcellulose (HPMC) was employed to control the particle size and morphology. The effects of experimental parameters, such as stirring time, drug concentration and drying methods, on particle size and morphology were investigated. The average particle size of AC obviously increased from 410 nm to 1200 nm as the stirring time changed from 30 s to 60 min. The enhancement of drug concentration favored to decrease the particle size from 410 nm to 240 nm. After spray drying process, ultrafine AC powder was obtained, which had good dispersibility and narrow particle size distribution of 1–3 μm. The as-prepared ultrafine AC was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermal gravimetric analysis (TG), differential scanning calorimetry (DSC), specific surface area and dissolution test. The XRD analyses indicated that the ultrafine AC was amorphous. In the dissolution tests, the amorphous AC ultrafine powder exhibited enhanced dissolution property when compared to the raw material.