Nano and Microparticulate Chitosan Based System for Formulation of Carvedilol Rapid Melt Tablet

PURPOSE

In the present study rapid melt tablets (RMT's) of carvedilol were prepared by using ionotropic-gelated chitosan nanoparticles using a spray-drying method. Carvedilol is beta-adrenergic antagonist and its oral bioavailability is about 25-35% because of first pass metabolism.

METHODS

The spray-dried microparticles were formulated into RMT's using a wet granulation process. The Formulation and optimization of carvedilol loaded RMTs using nano and microparticulate chitosan based system (NMCS) was done by using 32 factorial designs.

RESULTS

Drug entrapment efficiency of about 64.9 % (w/w) and loading capacity of 14.44% (w/w) were achieved for the microparticles, which were ranged from 1 μm to 4 μm in diameter. RESULTS of disintegration tests showed that the formulated RMTs could be completely dissolved within 40 seconds. Dissolution studies suggested that Carvedilol is released more slowly from tablets made using the microencapsulation process compared with tablets containing Carvedilol that is free or in the form of nanoparticles.

CONCLUSION

RESULTS shown that the development of new RMTs designed with crosslinked microparticle might be a rational way to overcome the unwanted taste of conventional RMTs and the side effects related to Carvedilol intrinsic characteristics. The development of Carvedilol NMCS using ludiflash as RMTs could be used as a promising approach for improving the solubility and oral bioavailability of water insoluble drug.

Tyrosinase-catalyzed site-specific immobilization of engineered C-phycocyanin to surface

Enzymatic crosslinking of proteins is often limited by the steric availability of the target residues, as of tyrosyl side chains in the case of tyrosinase. Carrying an N-terminal peptide-tag containing two tyrosine residues, the fluorescent protein C-phycocyanin HisCPC from Synechocystis sp. PCC6803 was crosslinked to fluorescent high-molecular weight forms with tyrosinase. Crosslinking with tyrosinase in the presence of L-tyrosine produced non fluorescent high-molecular weight products. Incubated in the presence of tyrosinase, HisCPC could also be immobilized to amino-modified polystyrene beads thus conferring a blue fluorescence. Crosslinking and immobilization were site-specific as both processes required the presence of the N-terminal peptide in HisCPC.

Triggering effect of N-acetylglucosamine on retarded drug release from a lectin-anchored chitosan nanoparticles-in-microparticles system

The aim of this study was to investigate the use of N-acetylglucosamine (NAG) to accelerate drug release from a lectin-modified carrier. A wheat germ agglutinin (WGA)-anchored salmeterol xinafoate (SalX)-loaded nanoparticles-in-microparticles system (NiMS) was prepared with an ionotropic gelation technique combined with a spray drying method. The formulated microparticles were spherical, with diameters ranging mainly from 2 to 8 μm; the drug entrapment efficiency was >70% (w/w), and the loading capacity was approximately 8% (w/w). Drug release from WGA-SalX-NiMS, within the first 4h, was approximately 30% less than that from SalX-NiMS, indicating an effect of lectin-modification to retard drug release from the NiMS. Due to "sugar-lectin" interactions, drug release from WGA-SalX-NiMS was substantially increased after the addition of NAG to the release medium. However, no significant influence of NAG was observed on the drug release profile of SalX-NiMS without WGA anchorage. The characteristics of NAG-WGA interaction may provide valuable insights into the "triggering-effects" of specific sugars on drug release from lectin-anchored carriers. These results suggest that it is possible to control drug release from a lectin-anchored drug delivery system using a specific sugar, and that the designed novel WGA-SalX-NiMS may be a suitable formulation for chronotherapy of asthma.

A novel spray-dried nanoparticles-in-microparticles system for formulating scopolamine hydrobromide into orally disintegrating tablets

Scopolamine hydrobromide (SH)-loaded microparticles were prepared from a colloidal fluid containing ionotropic-gelated chitosan nanoparticles using a spray-drying method. The spray-dried microparticles were then formulated into orally disintegrating tablets (ODTs) using a wet granulation tablet formation process. A drug entrapment efficiency of about 90% (w/w) and loading capacity of 20% (w/w) were achieved for the microparticles, which ranged from 2 μm to 8 μm in diameter. Results of disintegration tests showed that the formulated ODTs could be completely dissolved within 45 seconds. Drug dissolution profiles suggested that SH is released more slowly from tablets made using the microencapsulation process compared with tablets containing SH that is free or in the form of nanoparticles. The time it took for 90% of the drug to be released increased significantly from 3 minutes for conventional ODTs to 90 minutes for ODTs with crosslinked microparticles. Compared with ODTs made with noncrosslinked microparticles, it was thus possible to achieve an even lower drug release rate using tablets with appropriate chitosan crosslinking. Results obtained indicate that the development of new ODTs designed with crosslinked microparticles might be a rational way to overcome the unwanted taste of conventional ODTs and the side effects related to SH’s intrinsic characteristics.