Physicochemical characterization of a pectin/calcium matrix containing a large fraction of calcium chloride: Implications for sigmoidal release characteristics

Abstract

The physicochemical properties of pectin/ calcium matrix tablets were studied with an emphasis on the effect of over 50% of calcium chloride to better understand the fundamentals of the drug-release mechanisms. The absence of the adsorption of methylene blue onto the calciumcontaining pectin matrix served as evidence of the calciumion-induced in situ crosslinking of pectin chains. Visual and scanning electron microscopy observation showed the reinforced robustness of the pectin/calcium matrix, whereas cryo-SEM revealed the formation of a pectin aggregate network as a result of calcium-induced crosslinking. The aggregate network underwent gradual erosion to a lower density, which indicated the erosion of the matrix. However, little change in the texture of the pectin/calcium matrix was observed at earlier times, which was interpreted as the initial stages of drug-release retardation. The apparent viscosity of the pectin aqueous dispersion increased biphasically as the calcium amount increased. The initial sharp increase was interpreted as calcium-induced crosslinking, whereas the following gradual increase was ascribed to a possible salt effect. We concluded that the salt effect and calcium-induced crosslinking contributed to a series of physical changes of the pectin matrix, which correlated to the sigmoidal release of indomethacin from the pectin/calcium matrix tablet.

Anin situcrosslinked compression coat comprised of pectin and calcium chloride for colon-specific delivery of indomethacin

“…In previous study, we reported that fortification of pectin gels could be achieved via calcium cation-induced in situ crosslinking (Wei et al, 2006(Wei et al, , 2009Wu et al, 2007a;Wu et al, 2008). Consequently, significant slowing of the initial drug release and a sigmoid release pattern were observed with use of these pectin/calcium chloride (P/Ca) matrix systems.…”

Effect of a commercial pectinmethylesterase on tomato paste consistency

“…Consistency is highly dependent on crosslinking of pectin with divalent cations such as calcium (Slavov et al 2009;Wei et al 2009;Yoo et al 2009). However, the fact that the treatments with 0.5% w/w and 1% w/w of NovoShape™ increased tomato paste consistency throughout 3 hrs of assay (P < 0.05) without addition of divalent cations suggests that consistency is not limited by these elements in tomato paste, which can be observed in Figure 1a and c.…”

Theophylline-Loaded Pectin/Chitosan Hydrochloride Submicron Particles Prepared by Spray Drying with a Continuous Feeding Ultrasonic Atomizer

“…Furthermore, pectin can be used in the pharmaceutical field owing to its good biocompatibility [ 1 , 2 , 3 ]. For example, pectin can be crosslinked with calcium ions, which is a suitable delivery system to escort drugs from the mouth to the colon [ 4 , 5 ]. On the other hand, chitosan and chitosan hydrochloride chitosan ( Scheme 2 ) are cationic polysaccharide polymer derived from chitin, which can be found in the shells of shrimp, crabs, lobsters, etc.…”