Amphotericin-B entrapped lecithin/chitosan nanoparticles for prolonged ocular application.

Fungal keratitis is the major cause of vision loss worldwide. Amphotericin-B is considered as the drug of choice for fungal infections. However, its use in ophthalmic drug delivery is limited by the low precorneal residence at ocular surface as a result of blinking reflex, tear turnover and nasopharyngeal drainage. We report Amphotericin-B loaded lecithin/chitosan nanoparticles for prolonged ocular application. The prepared nanoparticles were in the size range of 161.9-230.5 nm, entrapment efficiency of 70-75%, theoretical drug loading of 5.71% with positive zeta potential of 26.6-38.3 mV. As demonstrated by antifungal susceptibility against Candida albicans and Aspergillus fumigatus, nanoparticles were more effective than marketed formulation. They exhibited pronounced mucoadhesive properties. In-vivo pharmacokinetic studies in New Zealand albino rabbit eyes indicated improved bioavailablity (∼ 2.04 fold) and precorneal residence time (∼ 3.36 fold) by nanoparticles prepared from low molecular weight chitosan as compared with marketed formulation.

Identification of novel PTP1B inhibitors by pharmacophore based virtual screening, scaffold hopping and docking.

Design and synthesis of protein tyrosine phosphatases-1B (PTP1B) inhibitors are important for the drugs targeted to treat diabetes and obesity. The pharmacophore modeling, docking and scaffold hopping techniques have been applied to discover the novel PTP1B inhibitors. The ten prioritized compounds (115-119, 120-121, 127, 130-131) from the library of 86 compounds were synthesized and found positive in the micro molar range for PTP1B in-vitro inhibitory assays as compared to Suramin (IC50 9.5 µM). Among these five active compounds (115-119) were tested in STZ-s induced diabetic rat model and the most active compound 115 in this test, was further tested in C57BL/KsJ-db/db mice where it significantly improved OGTT along with the fasting and random blood glucose level. The treatment by the compound 115 significantly improved the insulin resistance and insulin signaling by restoring the insulin level and normalizing the serum lipid profile. Compound 115 also augmented the insulin action by modulating the expression of genes involved in insulin signaling like IRS 1-2, PI3K, PTPN1, Akt2, AMPK and PPAR-α. Western blot analysis of both skeletal muscle and liver demonstrated that proteins and intermediate enzymes of insulin signaling were also increased as compared to control group. The compound 115 was also investigated for anti-adipogenic effect on 3T3L-1 cells. The compound 115 inhibited MDI induced lipid accumulation in a dose-dependent manner. The oral bioavailability of compound 115 was ∼10.29% after 30 mg/kg oral dosing assessed in rat.

Pharmacokinetic and metabolism studies of rohitukine in rats by high performance liquid-chromatography with tandem mass spectrometry.

A sensitive, selective, and rapid high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the quantification of rohitukine in rat plasma. HPLC was performed using a Symmetry-Shield C18 (5 µ, 4.6 × 150 mm) column, and isocratic elution with ammonium acetate buffer (pH4; 10 mM):methanol (08:92, v/v) at a flow rate of 0.6 mL/min. Sample clean-up involved solid phase extraction (SPE) of analyte and internal standard (phenacetin) from 100 µL plasma. The parent→product ion transitions (MRM) for analyte and IS were 306.1→245.1 m/z and 180.1→138.1 m/z respectively, and were monitored on a triple quadrupole mass spectrometer, operating in positive ion mode. The method was validated across the dynamic concentration range of 5-500 ng/mL for rohitukine, with a fast run time of 4.5 min. The analytical method measured concentrations of rohitukine with accuracy (% bias) of <±10% and precision (% RSD) of <±12%. Rohitukine was stable during the battery of stability studies viz., bench-top, auto-sampler, freeze/thaw cycles and 30 days of storage in a freezer at -70±10°C. Finally, the applicability of this assay has been successfully demonstrated in vivo pharmacokinetic and in vitro metabolism studies in Sprague-Dawley rat. This method will therefore be highly useful for future preclinical and clinical pharmacokinetic studies of rohitukine.