The role of the kneading paddle and the effects of screw revolution speed and water content on the preparation of solid dispersions using a twin-screw extruder.

The twin-screw hot-melt extrusion process is useful for preparing solid dispersions which can improve the dissolution and absorption of drugs. The kneading paddle elements of the screws play an important role in changing the crystallinity and dissolution properties of a solid dispersion of kneaded nifedipine-hydroxypropylmethylcellulose phthalate (NP-HPMCP). After operating the machine, a small amount of kneaded material adhering to the screws was collected and its physicochemical properties examined. Samples from the kneading paddle with a twist angle of 60 degrees were transparent and exhibited super-saturation on dissolution testing. When the kneading paddle elements were detached from the screws and only the feed screw elements were operated, the physicochemical properties of the extruded material were significantly influenced by the operating conditions of the machine e.g. revolution rate of screws, and the amount of water added to the feed materials. Slow revolution of the screws and the addition of a suitable amount of water to the mixture increased the rate of drug dissolution, although no super-saturation occurred. As the kneading paddle elements can retain the mixture in the machine for a longer period under intense shear, desired solid dispersions can be prepared routinely irrespective of the operating conditions. Moreover, a capillary rheometer can be useful to predetermine the amount of water added and the temperature for the preparation of solid dispersions using a twin-screw extruder.

[1]  S. Riegelman,et al.  Oral absorption of griseofulvin in dogs: increased absorption via solid dispersion in polyethylene glycol 6000. , 1970, Journal of pharmaceutical sciences.

[2]  K. Funatsu,et al.  Mixing mechanism of three‐tip kneading block in twin screw extruders , 2000 .

[3]  H. Fukui,et al.  Preparation of nifedipine-hydroxypropylmethylcellulose phthalate solid dispersion by twin screw extruder and its evaluation , 1996 .

[4]  Keiji Sekiguchi,et al.  Studies on Absorption of Eutectic Mixture. I. A Comparison of the Behavior of Eutectic Mixture of Sulfathiazole and that of Ordinary Sulfathiazole in Man. , 1961 .

[5]  Bruno C. Hancock,et al.  The Relationship Between the Glass Transition Temperature and the Water Content of Amorphous Pharmaceutical Solids , 1994, Pharmaceutical Research.

[6]  T. Ozeki,et al.  Controlled release from solid dispersion composed of poly(ethylene oxide)-Carbopol interpolymer complex with various cross-linking degrees of Carbopol. , 2000, Journal of controlled release : official journal of the Controlled Release Society.

[7]  T. Arita,et al.  Dissolution mechanisms of drug-polyvinylpyrrolidone coprecipitates in aqueous solution. , 1979, Chemical & pharmaceutical bulletin.

[8]  I. Sugimoto,et al.  Dissolution and Absorption of Nipedipine from Nifedipine-Polyvinylpyrrolidone Coprecipitate , 1980 .

[9]  I. Sugimoto,et al.  Application of solid dispersions of nifedipine with enteric coating agent to prepare a sustained-release dosage form. , 1985, Chemical & pharmaceutical bulletin.

[10]  Y. Kawashima,et al.  Spherical solid dispersion containing amorphous tolbutamide embedded in enteric coating polymers or colloidal silica prepared by spray-drying technique. , 1987, Chemical & pharmaceutical bulletin.

[11]  R. Skwierczynski Interaction between water and poly(vinylpyrrolidone) containing polyethylene glycol , 1999 .