Publications in February 2015

After an excellent start in January 2015, the number of chitosan-related articles slightly decreased in February. Scientific journals released 142 publications, which mainly focused on pharmaceutical preparations, nanoparticles and evaluation studies. Again, the three leading nations in chitosan research are China (40 articles), India (19) and USA (13). German scientists are placed among the top 10, as they contributed 5 reports.

Table: Scientific journals, which published the highest number of chitosan-related articles in February 2015. Source:  GoPubMed

The oral administration of drugs is often hampered by poor drug solubility, insufficient adhesion to the intestinal mucosa and low permeability across the intestinal barrier. Numerous studies reported about the advantageous features of chitosan-based drug delivery systems. Two exciting articles are presented below, which examined novel formulations of chitosan suitable for oral drug administration.

Cysteine modified and bile salt based micelles: Preparation and application as an oral delivery system for paclitaxel.

Xu W., Fan X., Zhao Y. et al.; Colloids Surface B Biointerfaces. Vol. 128C:165-171.Februray 2015

The objective of this study was to develop a micelle-based hydrophobic drug delivery system. Micelles were composed of three main components: Pluronic F127 chitosan (PF127-CS), Pluronic F127 cysteine (PF127-cysteine) and sodium cholate (NaC).
Pluronic block copolymers are surface active compounds, which form micelles due to their self-assembly capacity. Each block consists of a hydrophobic propylene oxide, flanked by two hydrophilic ethylene oxide blocks (EOx-POy-EOx). Pluronic micelles are approved pharmaceutical excipients and can be used for drug delivery. However, they display just a low loading capacity for hydrophobic drugs like paclitaxel. To improve the oral bioavailability of paclitaxel, PF127-CS was mixed with the bile salt NaC. PF127 was further modified by cysteine to improve mucoadhesive properties of the micelles and therefore the oral adsorption.

Results for PF127-CS/PF127-cysteine/NaC micelles:

• Spherical micelles with an average size of 60.3 nm
• Drug-loading capacity increased from 3.35% to 12.77% compared to PF127 micelles
• Enhanced micelle stability in aqueous solutions compared to NaC micelles
• Decreased cytotoxicity of empty micelles compared to NaC micelles
• pH-dependent drug release, faster at acidic pH conditions
• Sustained drug release in vitro
• Improved bioavailability of paclitaxel-loaded micelles compared to paclitaxel solution, in vivo

Conclusion: Micelles consisting of PF127-CS/PF127-cysteine/NaC formulations clearly improved the encapsulation efficiency and bioavailability of hydrophobic drugs. These micelles might display a real progress in the development of new oral delivery systems for drugs like paclitaxel.

Source: http://www.ncbi.nlm.nih.gov/pubmed/25747310

Improved oral therapeutic potential of nanoencapsulated cryptdin formulation against Salmonella infection.

Rishi P., Bhogal A., Arora S. et al.; European Journal of Pharmaceutical Sciences. Vol.  24;72:27-33. February 2015

This study introduces a novel strategy of oral drug administration, which shall improve delivery efficiency and bioavailability of antimicrobial drugs. The authors invented a chitosan: tripolyphosphate (5:2) formulation and encapsulate cryptdin-2 as model drug. Cryptdin peptides are also part of the mammalian immune defence and are secreted by cells of the small bowel to antagonise pathogens like salmonella. The antibacterial efficiency of cryptdin-loaded chitosan nanoparticles were analysed in Salmonella Typhimurium-infected mice.

Results:

• Particle size: 105 ±7 nm
• Zeta potential: -22.60 mV
• Polydispersity index: 0.384
• 60% drug entrapment efficiency
• 65% drug release in 4.5 h (in vitro)
• 83% survival rate of infected mice versus 100% mortality of free cryptdin-2-treated mice
• 2 log unit reduction of bacteria load
• Decreased level of oxidants: nitrite: 3.25 fold
• Increased level of antioxidants: catalase: 2 fold

Conclusion: The mortality of salmonella-infected mice was clearly diminished when animals were treated with chitosan-encapsulated cryptdin-2. Untreated or free cryptdin-treated animals displayed a mortality rate of 100 %. The improved survival rate is presumably mediated by a close contact with the gut mucosa, which prolonged the drug release and resorption time.

Source: http://www.ncbi.nlm.nih.gov/pubmed/25724130