Highly compressible paracetamol: I: crystallization and characterization

It was found that polyvinylpyrrolidone (PVP) is an effective additive during crystallization of paracetamol and significantly influenced the crystallization and crystal habit of paracetamol. These effects were attributed to adsorption of PVP onto the surfaces of growing crystals. It was found that the higher molecular weights of PVP (PVP 10 000 and PVP 50 000) were more effective additives than lower molecular weight PVP (PVP 2000). Paracetamol particles obtained in the presence of 0.5% w/v of PVP 10 000 or PVP 50 000 had near spherical structure and consisted of numerous rod-shaped microcrystals which had agglomerated together. Particles obtained in the presence of PVP 2000 consisted of fewer microcrystals. Differential scanning calorimetry (DSC) and X-ray powder diffraction (XPD) experiments showed that paracetamol particles, crystallized in the presence of PVP, did not undergo structural modifications. By increasing the molecular weight and/or the concentration of PVP in the crystallization medium the amount of PVP incorporated into the paracetamol particles increased. The maximum amount of PVP in the particles was 4.32% w/w. (C) 2000 Elsevier Science B.V. All rights reserved.