Evaluation of enzyme stability during preparation of polylactide-co-glycolide microspheres

This work was aimed at studying enzyme prolidase stability and its interactions with the reagents and the process conditions involved in preparation, by an emulsi®cation process, of prolidase loaded poly(lactide-co-glycolide) (PLGA) microparticulate systems. Enzyme stability was tested with respect to contact with methylene chloride, ethyl acetate, PLGA polymers, and several agents used as emulsi®ers such as polyvinyl alcohol (PVA), polyvinyl pyrolidone (PVP), carboxymethyl cellulose (CMC) and sodium oleate (NaOl). Enzyme stability to temperature and mechanical stirring was also evaluated. Prolidaseloaded PLGA microspheres were prepared and evaluated in terms of protein activity. The results obtained showed that the prolidase-loaded PLGA microspheres can be prepared only upon eyzyme stabilization by addition of both BSA and MnCl2 into its TRIS solution. Methylene chloride was the suitable organic solvent to be used in the double emulsion process, together with PVA as dispersing agent in the outer aqueous phase. Low temperatures during the emulsi®cation step and very short process times are recommended, in order to maintain enzyme activity at its maximum. In these conditions spherical microspheres were obtained, releasing active prolidase for up to 15 days

Enzyme loaded biodegradable microspheres in vitro ex vivo evaluation.

Prolidase is a naturally occurring enzyme involved in the final stage of protein catabolism. Deficient enzyme activity causes prolidase deficiency (PD), a rare autosomal recessive inherited disorder whose main manifestations are chronic, intractable ulcerations of the skin, particularly of lower limbs. Although several attempts have been made towards the treatment of this pathology, a cure for this disease has yet to be found. The purpose of this work is to evaluate the possibility of enzyme replacement therapy through prolidase microencapsulation in biodegradable microspheres. The poly(D,L-lactideco- glycolide) (PLGA) prolidase loaded microparticulate systems have been prepared utilizing the w–o–w double emulsion solvent evaporation method. They have been characterized ‘‘in vitro’’ by morphological analysis, total protein content and an in vitro dissolution test of active protein. ‘‘Ex vivo’’ evaluation of prolidase activity from the microspheres has been performed on cellular extracts of cultured skin fibroblasts from healthy subjects (controls) and from patients affected by PD. The results reported in this work on prolidase from pig kidney (available on the market) demonstrate the positive role of microencapsulation as a process of enzymatic activity stabilization inside PLGA microspheres achieving both in vitro and ex vivo active enzyme release. This formulation can be proposed as a parenteral depot drug delivery system

Enzyme loaded biodegradable microspheres in vitro ex vivo evaluation

Prolidase is a naturally occurring enzyme involved in the final stage of protein catabolism. Deficient enzyme activity causes prolidase deficiency (PD), a rare autosomal recessive inherited disorder whose main manifestations are chronic, intractable ulcerations of the skin, particularly of lower limbs. Although several attempts have been made towards the treatment of this pathology, a cure for this disease has yet to be found. The purpose of this work is to evaluate the possibility of enzyme replacement therapy through prolidase microencapsulation in biodegradable microspheres. The poly(D,L-lactideco- glycolide) (PLGA) prolidase loaded microparticulate systems have been prepared utilizing the w–o–w double emulsion solvent evaporation method. They have been characterized ‘‘in vitro’’ by morphological analysis, total protein content and an in vitro dissolution test of active protein. ‘‘Ex vivo’’ evaluation of prolidase activity from the microspheres has been performed on cellular extracts of cultured skin fibroblasts from healthy subjects (controls) and from patients affected by PD. The results reported in this work on prolidase from pig kidney (available on the market) demonstrate the positive role of microencapsulation as a process of enzymatic activity stabilization inside PLGA microspheres achieving both in vitro and ex vivo active enzyme release. This formulation can be proposed as a parenteral depot drug delivery system

Dual-functionalized PAMAM dendrimers with improved P-glycoprotein inhibition and tight junction modulating effect

10.1021/bm401057cBiomacromolecules14124226-4235BOMA

Mucoadhesive Microspheres for Gastroretentive Delivery of Acyclovir: In Vitro and In Vivo Evaluation

The aim of the present investigation was to evaluate the potential use of mucoadhesive microspheres for gastroretentive delivery of acyclovir. Chitosan, thiolated chitosan, Carbopol 71G and Methocel K15M were used as mucoadhesive polymers. Microsphere formulations were prepared using emulsion-chemical crosslinking technique and evaluated in vitro, ex-vivo and in-vivo. Gelatin capsules containing drug powder showed complete dissolution (90.5 ± 3.6%) in 1 h. The release of drug was prolonged to 12 h (78.8 ± 3.9) when incorporated into mucoadhesive microspheres. The poor bioavailability of acyclovir is attributed to short retention of its dosage form at the absorption sites (in upper gastrointestinal tract to duodenum and jejunum). The results of mucoadhesion study showed better retention of thiolated chitosan microspheres (8.0 ± 0.8 h) in duodenal and jejunum regions of intestine. The results of qualitative and quantitative GI distribution study also showed significant higher retention of mucoadhesive microspheres in upper GI tract. Pharmacokinetic study revealed that administration of mucoadhesive microspheres could maintain measurable plasma concentration of acyclovir through 24 h, as compared to 5 h after its administration in solution form. Thiolated chitosan microsphere showed superiority over the other formulations as observed with nearly 4.0-fold higher AUC0–24 value (1,090 ± 51 ng h/ml) in comparison to drug solution (281 ± 28 ng h/ml). Overall, the result indicated prolonged delivery with significant improvement in oral bioavailability of acyclovir from mucoadhesive microspheres due to enhanced retention in the upper GI tract