title: Sealing liquid-filled pectinate capsules with a shellac coating.
abstract: Liquid-filled pectinate capsules have a large potential for the controlled and site-specific delivery of liquid drugs. Earlier studies have shown that pure pectinate capsules can store drugs only for a few minutes. Here, we show that the retention time can be extended to several hours by coating the capsules with the natural resin shellac. A bilberry extract containing anthocyanins with promising therapeutic properties was used as model drug to characterize the permeability of the capsules by in vitro drug release measurements. Characterizing the structure of the double-layered capsule membranes by NMR microscopy, we optimized the capsule production by adjusting the pH-value in the coating process and the gelation time of the pectinate hydrogel layer. A comparison of the layer thicknesses with drug release measurements reveals that capsules with the thinnest shellac layers provide the best entrapment. Additional squeezing experiments show that the shellac layer makes the capsules also mechanically more stable.
authors: Department of Experimental Physics III, TU Dortmund University, 44227 Dortmund, Otto-Hahn-Strasse 4, Germany. stefan.henning@tu-dortmund.de
authors: Stefan
authors: S
authors: Henning
authors: Sabine
authors: S
authors: Leick
authors: Maureen
authors: M
authors: Kott
authors: Heinz
authors: H
authors: Rehage
authors: Dieter
authors: D
authors: Suter
mesh_terms: D002214:Capsules; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D010368:Pectins / Q000008:administration & dosage*; D012995:Solubility
chemical_list: D002214:Capsules; D010368:Pectins