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XEDS-mapping for explaining release patterns from single pellets

In English

Författare

Summary, in English

A common way to formulate controlled-release (CR) pharmaceuticals is to coat pellets of active substance with a polymer film, decrease the size of the pellets and distribute them as multiple-unit dosages in capsules. To increase the understanding of the release mechanism, the pellet shape and surface structure of pellets, before and after release in microtitre plates, have been studied by scanning electron microscope and X-ray energy-dispersive spectrometry. By performing these studies we associate release profiles during the first few hours to the microscopic structure. Pellets were divided into three classes (spherical pellets, dumbbell shaped pellets and twin-pellets) according to pellet form. Cases of burst release occurred for all three shape classes due to "open-window-defects" at the surface. Areas of thinner polymer film in the neck-region of dumbbell shaped pellets broaden the range of intermediate release rates for this pellet shape. The surface of twin pellets and dumbbell shaped pellets showed more defects, which increases the release rates in comparison to spherical pellets. All pellets with high release rates revealed ruptures in the polymer film, whereas only small cracks could be traced for pellets with slow release rates. The information gained is necessary for the development of future formulations and mathematical modelling of release patterns. The pharmaceutical used as model was remoxipride coated with a polymer film of ethyl cellulose and 10 wt.% triethyl citrate. (C) 2004 Elsevier B.V. All rights reserved.

Publiceringsår

2005

Språk

Engelska

Sidor

109-120

Publikation/Tidskrift/Serie

International Journal of Pharmaceutics

Volym

290

Issue

1-2

Dokumenttyp

Artikel i tidskrift

Förlag

Elsevier

Ämne

  • Chemical Engineering
  • Chemical Sciences

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 1873-3476