Simultaneous determination of simvastatin, lovastatin and niacin in human plasma by LC-MS/MS and its application to a human pharmacokinetic study.

A simple, sensitive and specific LC-MS/MS method for simultaneous determination of simvastatin (SV), lovastatin (LV) and niacin (NIA) in human plasma was developed and validated on API-4000 in positive ion mode. Nevirapine was used as internal standard (IS). The assay procedure involved a simple one-step liquid-liquid extraction of SV, LV, NIA and the IS from plasma into ethyl acetate. Separation of SV, LV, NIA and the IS was achieved on an Alltima C18 column with a mobile phase consisting of 5 mm ammonium acetate (pH 4.5) and acetonitrile (20:80, v/v) pumped at a flow rate of 1 mL/min. Nominal retention times obtained for SV, LV, NIA and IS were 2.12, 1.67, 0.50 and 0.65 min, respectively. The lower limits of quantification (LLOQ) for SV, LV and NIA were 0.10, 0.10 and 25.2 ng/mL, respectively. The response function was established for the range of concentrations 0.10-101 ng/mL for SV and LV, and 25.2-5020 ng/mL for NIA, with a coefficient of correlation of >0.99 for all the compounds. Method validation was performed as per FDA guidelines and the results met the acceptance criteria. The proposed method was found to be applicable to clinical studies.

Medical ablation of endobronchial mucormycosis with Amphotericin-B.

A 56 years male diabetic patient presented with recurrent left upper lobe pneumonia. Fiberoptic bronchoscopy revealed extraluminal compression of left main bronchus with an endobronchial mass obstructing the left upper lobe orifice. The lesion resembled bronchial adenoma. However histological examination revealed mucormycosis. Timely diagnosis followed by medical intervention with intravenous Amphotericin B, coupled with proper management of diabetes, ablated the tumor. Relevant literature on the subject is reviewed.

Morphology and release kinetics of technetium-99m(V) dimercaptosuccinic acid loaded, poly(lactic-co-glycolic)acid microspheric delivery system. An experimental approach that may be used for targeted radiation treatment.

The aim of our studies was to formulate a system that delivers the required radiation dose to the tumor site and minimize the harm to other organs or tissues. The poly (lactic-co-glycolic acid, 75:25; 50:50) microspheric radiation delivery system was fabricated using double emulsion solvent evaporation technique for the encapsulation of technetium-99m(V)dimercaptosuccinic acid ((99m)Tc(V)DMSA). Microspheres of different sizes (0.2-20.0 mum) were prepared. The initial burst in microspheres with 10% and 1% poly vinyl alcohol (PVA) in the presence of poly ethylene glucol (PEG) was as 30% and 16% respectively, however the initial burst in microspheres without the PEG was 9% and 1.2% respectively. The results indicated that smaller microspheres had higher encapsulation (68%) of (99m)Tc(V)DMSA than larger microspheres (15%). The stirring rate changed the surface of the microspheres from smooth spherical, to spherical, porous. The ratio of co-polymers (75:25/50:50) affected the release kinetics. In conclusion, our studies with varied surfactant concentrations, co-polymer concentrations and speed of solvent evaporation, on the morphology and release kinetics of (99m)Tc(V)DMSA from the microspheres, may be applied for the fabrication of targeted radiotherapeutic microspheres by substituting (99m)Tc(V)DMSA with rhenium-188 (V) DMSA ((188)Re(V)DMSA). (188)Re(V)DMSA is a therapeutic analogue of (99m)Tc(V)DMSA and both share similar radiopharmaceutical properties.

Insights into RpoB clinical mutants in mediating rifampicin resistance in Mycobacterium tuberculosis.

Rifampicin (RIF) an essential first-line anti-tuberculosis (TB) drug, resistance to RIF is a potential threat to TB control program and widely considered as surrogate marker for detection of multi-drug resistant-TB (MDR-TB), molecular understanding of which is the utmost need of the hour. Mutations at RIF resistance-determining region (RRDR) of 81-bp in the rpoB gene coding for ß subunit or RpoB protein is the major cause of RIF resistance in Mycobacterium tuberculosis (MTB). Mutation at positions 526 and 531 are generally associated with high-level RIF resistance and at codons 516, 521 and 533 with low-level resistance. Thus, in order to understand the interactions between the clinical mutants (MTs) of RpoB and RIF which are responsible for mediating both levels of RIF resistance from MTB. In the present study, models of wild type (WT) and seven MTs (D516V, L521M, H526D, H526R, H526Y, S531L and L533P) of RpoB from MTB were generated using crystal structure of 2A68 and 4KBM as templates, for deducing 3 domains structure. Molecular docking between RpoB proteins and RIF was carried out, which showed higher values for WT compared to MTs. The high score in WT may be due to the presence of favorable interactions with RIF and MT-L521M which lacks in other MTs. Molecular dynamics (MD) simulation was performed for over 10 nanoseconds, which suggest the root mean square deviation (RMSD) was more and root mean square fluctuation (RMSF) was less in WT compared to MTs. The ligand RMSD exhibited very unique deviation with the MT-D516V compared to other MTs and WT. The RMSF for MTs such as H526R-H526D, L521M and D516V were higher for residues such as 152, 265, 352, 402, 513, 552, and 577 compared to WT. Hydrogen bond interactions at RIF binding site after MD simulations were found comparatively lower in WT than MTs. Similarly, the binding energy of WT was observed to be lesser in comparison to MTs. All MTs demonstrated certain (2Å) degree of structural deviation from the WT. Overall, these results suggest that RIF binding ability shows differences between WT and MTs, which could be because of different substitutions affecting the conformation of the MT proteins, leading to changes in binding interactions with RIF, eventually to the cause of RIF resistance.

Tamoxifen-2-hydroxylpropyl-beta-cyclodextrin-aggregated nanoassembly for nonbreast estrogen-receptor-positive cancer therapy.

BACKGROUND: Tamoxifen (Tam) is used for the treatment and prevention of estrogen-receptor-positive human breast and other cancers. Its use in ovarian cancer has not been well studied. METHOD: We formulated and characterized a water-soluble Tam-2-hydroxylpropyl-beta-cyclodextrin (HPbetaCD; 1:2 M) complex. RESULTS: The differential scanning calorimetery of Tam-HPbetaCD indicated the transition of Tam from crystalline to amorphous form on addition of HPbetaCD. (1)H-nuclear magnetic resonance nuclear overhauser effect cross-peaks between phenyl moieties of Tam and HPbetaCD, and downfield shifts in H-3 (0.26) and H-5 (0.29) protons of HPbetaCD suggested the inclusion of Tam in HPbetaCD cavity. Transmission-electron microscopy studies of HPbetaCD and the Tam-HPbetaCD complex revealed the formation of aggregated nanoassembly at 60-180 nm. Dimethyl thiazol diphenyltetrazolium bromide assay demonstrated 7.37 +/- 2.32% cell survival of OAW-42 cells with 3 microg/ml Tam concentration. CONCLUSION: The Tam-HPbetaCD nanoassembly entered the cell owing to enhanced permeability and retention property of tumor cell and antiestrogenic Tam and, therefore, resulted in excellent anticancer efficacy in the ovarian cancer cell line.