Bipul Nath* and Tushar Kanti Roy
In the present investigation, the compatibility of Atorvastatin calcium was evaluated with various superdisintegrants and other solid excipients by means of FT-IR and DSC. Several batches of tablets with varying proportion of superdisintegrants were prepared by direct compression techniques. Tablets were also evaluated for different physical properties and in-vitro drug release characteristics and optimized its release comparable to marketed innovator product. Various excipients used were sodium starch glycollate, Cross carmellose sodium, Cross-povidone, lactose, Micro crystalline cellulose, mannitol, sodium alurayl sulfate, magnesium stearate, and stearic acid. From the DSC studies, the excipients such as microcrystalline cellulose (Avicel 101), magnesium stearate, mannitol, Sodium lauryl sulfate were found to have physical interactions with Atovastatin. Immediate release tablet was prepared by direct compression method and its release profile was compared with the marketed IR tablet. The prepared tablet have conform the pharmacopoeial limit for hardness, thickness, friability, weight variation and content uniformity. Formulation F11 containing two super disintegrants have shown the disintegration time less than 25 sec and better dissolution than all other formulations releasing more than 80% of the drug after 20 minutes. Kinetic data reveals that the drug release follows best order by Higuchi model, followed by korsemeyer peppas, zero order and first order mechanisms. The results of accelerated stability studies as per ICH guidelines indicated that the tablet was stable as there were no any significant physical changes after the study.
Hao Gu, Katherine Ji, Rongji Dai, Yen Wei, and Hai-Feng Ji*
Traditional molecularly imprinted polymer (MIP) prepared from bulky samples may lose its selectivity during the crushing procedure. In this work, we report a one-step approach to prepare MIP materials in the shape of mesoporous silica particles. The mesoporous silica particles were prepared in the presence of template molecules in order to gain selectivity for the template molecules. After thorough rinsing, re-absorption experiments showed that L-tyrosine templated silica particles PL-t absorbed more L-tyrosine than its enantiomer D-tyrosine, and serotonin-templated silica particles Ps absorbed more serotonin than its analogue, tryptophan. These results demonstrated that templated silica particles have the capability of selective absorption of the template molecules.
Arteaga-Jimenez A1, Martinez-Balbuena L*, Hernandez-Zapata E, and Lopez-Esparza R
DOPS liposome formation experiments using the rehydration technique in ionic solutions are reported. We present observations on the ionic strength dependence of the liposome morphology and size. Shape changes from spheres to coiled cylindrical vesicles as the salt concentration increases. From optical microscopy observations and a Winterhalter-Helfrich theoretical model we infer that the counter ion presence leads to an increase in the liposome curvature elasticity, in such a way that small mechanical perturbations are able to radically transform the liposome morphology.
Mehrdad Tajkarimi, Kristen Rhinehardt, Misty Thomas, Jude Akamu Ewunkem, Adero Campbell, Sada Boyd, Devana Turner, Scott H. Harrison, and Joseph L. Graves Jr*
Escherichia coli can rapidly evolve resistance to silver nanoparticles (AgNP). Here we utilize experimental evolution to demonstrate that selection for Ag+ resistance confers resistance to AgNPs. By generation 200, the minimum inhibitory concentration of Ag-selected increased by ~9.5-fold compared to control replicates. Ag-selected replicates also showed superior resistance to AgNPs. Genomic analysis identified candidate mutations in the silver-resistant lines including several in the gene cusS, which encodes a histidine kinase that senses copper and silver ions, as well as ompR, outer membrane protein R, and in the RNA polymerase subunits (rpoA, rpoB, rpoC). Molecular simulations of the common cusS mutations showed that they imputed greater silver ion affinity compared to that of the ancestral cusS sequence. This study supports the contention that the primary action of AgNPs against bacteria is the release of Ag+ ion. Furthermore it validates that bacterial resistance to silver can occur rapidly by simple genomic changes.