European Journal of Pharmaceutical Sciences 24 (2005) 363–373 Emulsion gel beads of calcium pectinate capable of floating on the gastric fluid: effect of some additives, hardening agent or coating on release behavior of metronidazole Pornsak Sriamornsak a,∗ , Nartaya Thirawong a , Satit Puttipipatkhachorn b a DepartmentofPharmaceuticalTechnology,FacultyofPharmacy,SilpakornUniversity,NakhonPathom73000,Thailand b DepartmentofManufacturingPharmacy,FacultyofPharmacy,MahidolUniversity,Bangkok10400,Thailand Received 5 October 2004; received in revised form 2 December 2004; accepted 10 December 2004 Available online 23 January 2005 Abstract Emulsion gel (EMG) beads of calcium pectinate capable of floating in the gastric condition were developed using an emulsion-gelation method and their release properties were investigated. Attempts to modify the drug release were made by applying some additives into the starting solution prior to bead formation, by hardening with glutaraldehyde, and by coating with polymer. The metronidazole-loaded EMG beads were found to float on simulated gastric fluid. Increasing the drug to pectin ratio in the beads slowed the drug release from the conventional and the EMG beads. However, the drug release from these beads was rapid, i.e., about 80% of drug loading released within 20–80 min. The additives (PEG10000, glyceryl monostearate and Eudragit ® L) had a slight, insignificant, effect on the drug release. Using 2% glutaraldehyde as a hardening agent prolonged the drug release. Coating the beads with Eudragit ® RL significantly sustained the drug release while the beads remained buoyant. The results suggest that EMG beads are suitable as a carrier for intragastric floating drug delivery and that their release behaviour could be modified by hardening with glutaraldehyde or by coating with Eudragit ® RL. © 2004 Elsevier B.V. All rights reserved. Keywords: Calcium pectinate; Pectin; Emulsion gel; Beads; Floating; Additives; Sustained release 1. Introduction Oral administration is always the preferred means of drug delivery to the systemic circulation. Many attempts have been made to develop sustained release preparations with extended clinical effects and reduced dosing frequency. A problem frequently encountered with conventional sustained release dosage forms is the inability to increase their residence time in the stomach and proximal portion of the small intestine. Retention of drug delivery systems in the stomach prolongs the overall gastrointestinal transit time, thereby resulting in improved oral bioavailability of the basic drugs that have poor solubility in higher pH, and of drugs susceptible to circadian ∗ Corresponding author. Tel.: +66 34 253912x2317; fax: +66 34 255801. E-mailaddress: pornsak@email.pharm.su.ac.th (P. Sriamornsak). variations (Moes, 1993). These systems are also appropriate for drugs which are locally active to the gastric mucosa in the stomach, for example, antibiotic administration for He- licobacterpylori eradication in the treatment of peptic ulcer disease (Cooreman et al., 1993). Floating dosage forms can be used to retain the deliv- ery system in the stomach to increase the gastric residence time. Various methods have been used to prepare the float- ing dosage forms (Hwang et al., 1998; Singh and Kim, 2000). The most commonly used excipients are gel-forming or highly swellable cellulose type hydrocolloids, polysaccha- rides, and matrix forming polymers such as polycarbonate, polyacrylate, polymethacrylate and polystyrene (Singh and Kim, 2000). Floating properties of dosage form can also be fabricated using oils, for example, tablets containing mineral oil-entrapped agar (Desai and Bolton, 1993). 0928-0987/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.ejps.2004.12.004