Encapsulation of ketoprofen for controlled drug release.

Ketoprofen particles were encapsulated with polyions and gelatin to control the release of the drug in aqueous solutions. Charged linear polyions and gelatin were alternatively deposited on 6 microm drug microcrystals through layer-by-layer (LbL) assembly. Sequential layers of poly(dimethyldiallyl ammonium chloride) (PDDA) and poly(styrenesulfonate) (PSS) were followed by adsorption of two to six gelatin/PSS bilayers with corresponding capsule wall thicknesses ranging from 41 to 111 nm. The release of Ketoprofen from the coated microparticles was measured in aqueous solutions of pH 1.4, 4.1, and 7.4. The release rate has changed at these different pH values. At pH 7.4 the release rate of Ketoprofen from the encapsulated particles was less by 107 times compared to uncoated Ketoprofen. The results provide a method of achieving prolonged drug release through self-assembly of polymeric shells on drug crystals.

Simultaneous determination of irbesartan and hydrochlorothiazide in human plasma using HPLC coupled with tandem mass spectrometry: Application to bioequivalence studies.

A sensitive, specific and selective liquid chromatography/tandem mass spectrometric method has been developed and validated for the simultaneous determination of irbesartan and hydrochlorothiazide in human plasma. Plasma samples were prepared using protein precipitation with acetonitrile, the two analytes and the internal standard losartan were separated on a reverse phase C(18) column (50mmx4mm, 3microm) using water with 2.5% formic acid, methanol and acetonitrile (40:45:15, v/v/v (%)) as a mobile phase (flow rate of 0.70mL/min). Irbesartan and hydrochlorothiazide were ionized using ESI source in negative ion mode, prior to detection by multiple reaction monitoring (MRM) mode while monitoring at the following transitions: m/z 296-->269 and m/z 296-->205 for hydrochlorothiazide, 427-->175 for irbesartan. Linearity was demonstrated over the concentration range 0.06-6.00microg/mL for irbesartan and 1.00-112.00ng/mL for hydrochlorothiazide. The developed and validated method was successfully applied to a bioequivalence study of irbesartan (300mg) with hydrochlorothiazide (12.5mg) tablet in healthy volunteers (N=36).

Cellactose a co-processed excipient: a comparison study.

This article describes the differences in compaction properties between microcrystalline cellulose (MCC) and alpha-lactose monohydrate physical mixture, and microcrystalline cellulose co-processed with alpha-lactose monohydrate (Cellactose). The different compaction parameters are not only compared for the pure materials but also for the lubricated powders with magnesium stearate. Magnesium stearate does not facilitate the densification of either the physical mixture or Cellactose during compaction. The difference in tablet relaxation of the physical mixture and Cellactose indicates that the negative effect of the lubricant on the interparticle bonding of Cellactose particles is smaller than the physical mixture particles because after compaction, the structure in the Cellactose tablet is completely different from that in the physical mixture tablet. However, a larger increase in tablet relaxation at a high compression speed was found for both Cellactose and the physical mixture at different lubricant concentrations: 1.0% and 0.0%. Accordingly, the decrease in tablet strength was larger for the physical mixture tablets than for the Cellactose tablets when lubrication was applied. The examination of the tablet strengths of tablets compressed from physical mixtures of different ratios of alpha-lactose monohydrate and MCC proved the positive effect of cellulose on the tensile strength of tablets. Co-processing of MCC with alpha-lactose monohydrate showed extra contribution on the tablet strength of a physical mixture with the same mixing ratio. This extra contribution of Cellactose was attributed only to the interfacial attraction of the particles.