Hydrocolloid carriers with filler inclusion for diltiazem hydrochloride release

Hydrocolloid beads based on agarose, alginate (both 3%, w/w), or gellan (2%, w/w) were produced to study their potential as drug carriers. The beads included various fillers: talc, kaolin, calcium carbonate, potato, or corn starch (10%, w/w). After gelation, the carriers were subjected to either freeze- or vacuum-drying. The dried carriers were spheroids. The diameters of freeze- and vacuum-dried carriers ranged from 2.4 to 4.1 mm and 1.5 to 2.8 mm, respectively. The porosity values of the freeze-dried carriers were significantly higher than those of their vacuum-dried counterparts. Scanning electron microscopy (SEM) revealed that all dried carriers included internal voids that were partially occupied by the filler particles. Upon their introduction into simulated gastric fluid (3 h), followed by 6 h in intestinal fluid, all carriers were stable and underwent swelling. Release profiles of diltiazem hydrochloride from different carriers were obtained during immersion in dissolution medium. Filler inclusion (but not the type of filler) contributed to the stability of the carriers and prolonged the time of drug release (6.5-8.5 h) relative to the faster drug release from carriers that contained no filler (3.5 h). In summary, alginate, agar, and gellan beads with filler inclusion may be useful for slow drug release. (c) 2006 Wiley-Liss, Inc. and the American Pharmacists Association.