Preparation, in vitro release, in vivo absorption and biocompatibility studies of insulin-loaded microspheres in rabbits

Abstract

The purpose of this study was to develop a single-dose insulin delivery system based on poly (lactide-co-glycolide) (PLGA) microspheres to provide basal insulin level for a prolonged period. Insulin-loaded PLGA microspheres were prepared by water-in-oil-in-water double emulsion (batch A) and solid-in-oil-in-water emulsion (batch B) methods. Microspheres were characterized for physical characteristics and in vitro release. In vivo absorption of insulin and biocompatibility of insulin-loaded PLGA microspheres were performed in diabetic New Zealand white rabbits. Light and transmission electron microscopy were performed on the skin tissues excised from microspheres injected sites in order to study the biocompatibility. The burst release of insulin was high (47%) from batch B and low (5%) from batch A. Therefore, we mixed microspheres of batch A and B in ratio of 3:1 w/w, which produced desirable in vitro release profile. In vivo absorption study showed that insulin-loaded microspheres provided a serum insulin level of 20-40 μU/ml up to 40 days. Biocompatibility study provided evidence of normal inflammatory and foreign body reactions, which were characterized by the presence of macrophages, fibroblasts and foreign body giant cells. Neither necrosis nor tissue damage was identified. At the end of 12 weeks, no distinct histological differences were observed in comparison to the control tissue samples. In conclusion, insulin-loaded PLGA microspheres controlled the in vivo absorption of insulin to maintain the basal insulin level for longer period and the delivery system was biocompatible.

Liraglutide-loaded poly(lactic-co-glycolic acid) microspheres: Preparation and in vivo evaluation

“…Our results offer a significant addition to the extant studies using drug-loaded PLGA microspheres to treat diabetes, and add additional depth to these because often detailed studies of hypoglycemic effect are not reported (Jiang et al, 2003;Kang and Singh, 2005). There are many papers concerned with the toxicological and safety profiles of PLGA, and our data concur with these in demonstrating the safety of the materials (Semete et al, 2010;He et al, 2006;Hara et al, 2008).…”

“…The literature reports that using PLGAencapsulated insulin can give a hypoglycemic effect lasting from 5 to 15 days (Jiang et al, 2003;Kang and Singh, 2005). Our research indicates that the hypoglycemic effect of liraglutide-loaded PLGA microspheres can be maintained for around 30 days.…”

Solid-in-oil dispersion: A novel core technology for drug delivery systems

“…Moreover, the effects of addition or covalent modification by PEG or cyclodextrins were investigated using ␣ or ␥-chymotrypsin as model proteins (Castellanos et al, , 2005a(Castellanos et al, , 2005b(Castellanos et al, , 2006Castellanos and Griebenow, 2003;Perez et al, 2002). A similar method has been used to prepare a PLGA microsphere containing vascular endothelial growth factor (Kim and Burgess, 2002), human growth hormone (hGH) (Takada et al, 2003), insulin (Kang and Singh, 2005;Andreas et al, 2011), immunoglobulin G (Wang et al, 2004), glial cell linederived neurotrophic factor (Checa-Casalengua et al, 2011), typical model proteins such as lysozyme, ␣-chymotrypsin, peroxidase and ␤-galactosidase (Giteau et al, 2008), BSA-loaded calcium phosphate nanoparticles (Pitukmanorom et al, 2008), BSA-loaded dextran glassy particles (Yuan et al, 2010), recombinant human granulocyte colony-stimulating factor-loaded glassy sodium hyaluronate particles (Wu et al, 2011), recombinant human erythropoietin and human serum albumin mixture microparticles (He et al, 2011), BSA-or ␤-galactosidasen-loaded dextran nanoparticles , BSA-loaded porous silicon microparticles (Fan et al, 2011) and zinc-BSA nanoparticles (Ma et al, 2012). In these procedures, proteins or protein-loaded particles were directly dispersed into the oil phase to form S/O suspensions.…”

Biocompatibility of polyhydroxybutyrate microspheres: in vitro and in vivo evaluation

“…The reason for this is that macrophages and foreign body giant cells phagocytize and resorb biodegradable materials. (Kang and Singh, 2005), and poly(methylidene malonate 2.1.2 (Fournier, et al, 2006).…”