A novel approach for the manufacturing of extended release pellets / Juan Carlos Menéndez; committee chair: Adel Sakr, Ph.D.

Title from electronic thesis title page (viewed Oct. 14, 2003)

Includes abstract

Thesis (Ph.D.)--University of Cincinnati, 2003

Includes bibliographical references

Metronidazole pellets with a concentration of 88 % were prepared in the rotary fluid-bed spray granulator GPCG-1 using Kollidon 30ʼ. The effect of Eudragit L 30 D-55ʼ (enteric-coating) and/or Eudragit NE 30 Dʼ was, individually and as consecutive layers, evaluated on the release of metronidazole up to 30 % of weight gain of dry polymer.These pellets were tested in the USP XXVI apparatus 1 (baskets) at 100 rpm for 2 hours in acidic medium (0.1 N hydrochloric acid) followed by pH 6.8 phosphate buffer up to 24 hours. More than 10 % of weight gain of enteric-coating is required to effectively block drug release in acidic medium. Pellets coated with Eudragit NE 30 D showed bi-phase dissolution with the higher release rate in acidic medium and sustained release for the remaining 22 hours in phosphate buffer pH 6.8. The pellets prepared by the layering of the two film-coatings showed intermediate properties between delayed release in the acidic stage and sustained release thereafter. In a second stage of this study, the effect of three different filler-binders (microcrystalline cellulose, lactose and dicalcium phosphate) was evaluated on the protection of coated (30 % of weight gain) metronidazole pellets during compression. Enteric-coated pellets manufactured with Eudragit L 30 D-55 formed hard tablets; but the integrity of the coating was lost as determined by the in-vitro release test. Sustained-release pellets manufactured with Eudragit NE 30D, formed tablets with lower overall release after 24 hours than the uncompressed pellets; the decrease was especially evident for the tablets compressed without filler-binder, however these tablets did not bind. A third group of pellets was manufactured having both enteric and sustained release characteristics by coating with Eudragit NE 30D: Eudragit L 30 D-55 (15 % weight gain for each layer). The tablets from these pellets compressed with dicalcium phosphate, as well as the uncompressed pellets, meet the XXVI USP specifications for delayed release. Hardness of tablets depends, mainly, on the type of compressed pellets. Those prepared from uncoated and enteric-coated pellets yielded the hardest tablets. Tablets from dicalcium phosphate showed the lowest hardness and the lowest in-vitro drug release rates; therefore, it is hypothesized that the decreased release rate is related to the long disintegration time of the tablets

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