Controlled release of active as a consequence of the die diameter in solid lipid extrusion

The aim of the study was the investigation of dependency of the release profile on the original diameters of milled extrudates manufactured by solid lipid extrusion. Different die diameters in the range of 0.3 mm to 5.0 mm were used. The extrudates were milled and sieved. The fractions between 315 mu m and 400 mu m were investigated within their shape, surface area and dissolution profiles by using the dissolution tester and the disintegration tester for short-time dissolution tests. Different pH-media were used for the release tests: pH 1.2 to imitate release conditions in the stomach and pH 7.4 to imitate conditions in the mouth. The chosen active enrofloxacin, a derivate of 3-quinolinecarboxylic acid, offers different solubilities in these release media. Two conclusions of this study were obtained: In the case of slightly solubility of active in the medium there was no dependency of the released active on the die diameter. If the active was very slightly soluble in the release medium a dependency between the two parameters was found. Having bad tasting actives like enrofloxacin, this achievement has an enormous impact on the manufacturing processes: a reduction of die diameters and therefore reduction of released amount of active will lead to taste masking. (C) 2008 Elsevier B.V. All rights reserved.