Microencapsulation by Spray Coagulation of Diltiazem HCl in Calcium Alginate-Coated Chitosan

Abstract

Abstract. The aim of this work was to develop a procedure for encapsulation of diltiazem HCl by spray coagulation. Factors affecting the formulations such as the effect of NaCl on the solubility of diltiazem in alginate solution, surface tension, pH, viscosity of the coagulation medium, and the effect of drug load on drug release were studied. The drug load was increased substantially from 10 up to 320 mg/mL by adding 1.2% w/v NaCl in 1% w/v alginate solution. More stable microcapsules were obtained at pH 4.6 (acetate buffer) than at a pH 2.8 (lactic acid), and the microencapsulation process was favored by the type of chitosan that produced low turbidity and viscosity in the coagulation medium. A dose of 50 mg/mL of diltiazem HCl, 1.2% w/v NaCl, and chitosan CS allowed higher amount of drug to be encapsulated. The high water solubility of diltiazem HCl leads to fast release from the microcapsules.

Chitosan-based polyelectrolyte complexes as pharmaceutical excipients

“…In this case, the active agent, mostly depending on its solubility, is dissolved either in the polyanion solution (Sahasathian et al, 2010;Tapia et al, 2008) or in the chitosan solution (Dutta and Sahu, 2012;Kaur and Kaur, 2012). In this case, the active agent, mostly depending on its solubility, is dissolved either in the polyanion solution (Sahasathian et al, 2010;Tapia et al, 2008) or in the chitosan solution (Dutta and Sahu, 2012;Kaur and Kaur, 2012).…”

“…The loading of small molecules in chitosan-alginate microcapsules and the release rate may depend on the ionic force (Tapia et al, 2008) and the pH (Lee et al, 1997) of the solutions where the reactions and microencapsulation occur. Loading of the antihypertensive agent diltiazem.HCl in chitosan-alginate microcapsules prepared by the spray coagulation method increased from 10 to 320 mg/mL by adding an appropriate quantity of NaCl to the alginate solution (Tapia et al, 2008).…”

The Effect of Chitosan as Internal or External Coating on the 5-ASA Release from Calcium Alginate Microparticles

“…Each assay was done in triplicate. The dissolution data were analyzed according to Dobashi's model for fast release in acid and phosphate (14) and Weibull's model for prolonged release in water (16). From these models, the mean dissolution time, T 50 , was estimated.…”

“…The smaller individual size of CaAlCS in acid medium has been described previously. It was found that the presence of chitosan restricts the penetration of the solvent into the core of calcium alginate and thus maintains a smaller size (14). In acid medium, the fast release of 5-ASA from the CaAl would be favored by the high solubility of the drug and because the alginate is in its unionized form so that the matrix would not suffer a swelling-erosion process.…”

“…It has been reported that the mean size of the rehydrated calcium alginate microcapsules at pH 8.0 is significantly much larger than in acid medium (pH 1.2). However, when the microcapsules were coated with chitosan, no significant difference in the mean sizes was observed between both media (14). The aim of this work was to evaluate the effect of chitosan as coating agent for mesalamine (5-ASA) prior to encapsulation and as external coating in calcium alginate microparticles on drug release and to develop a delayed release of 5-ASA system intended for colonic drug delivery.…”