Certain rheologycal behaviour of paracetamol solid dispersion powders

Paracetamol powder (PAR) has poor compressibility, high cohesivity and is difficult to compress. We have prepared dispersions of PAR and 3-cyclodextrin (β-CD) in physical mixture form, kneaded solid dispersion and spray dried solid dispersion (the ratio 1:1 w/w), and spray dried solid dispersion of PAR-Ethocel-Macogol 6000 (95:2:3), as well. The Theological characteristics of this dispersions were observed. The crystalline structure, size and shape of PAR dispersion powders differed from PAR alone. Consequently, they showed improvement in packing density; reductions in cohesivity (Kawakita's cohesivity constant was the lowest with kneaded solid dispersion PAR-β-CD); good flowability and angle of repose (especially with kneded solid dispersion PAR-β-CD). We also examined the rheological behaviour of tablet formulations prepared from those dispersions and found some correlation between the weight variation of tablets and the mixture flow properties