Screening, isolation, taxonomy and fermentation of an antibiotic producer Streptomyces xinghaiensis from soil capable of acting against linezolid resistant strains.

Linezolid resistant cultures are emerging in hospitals. In the present study 3 soil actinomycetes were isolated in a screening programme having potential to produce antibiotic against linezolid resistant cases. One culture was coded as RK-46 and further studied. The micromorphology, biochemical tests and 16S ribosomal DNA gene sequence analysis were conducted to know the identity of the culture and was found as a strain of Streptomyces xinghaiensis. The culture produced antibiotic active against five clinical resistant strains. The antibiotic production was tested by cultivating in eleven different media. The fermentation profile was studied in YEME medium supplemented with calcium carbonate. The maximum activity was noticed at 72 h. Antibiotic activity was extracted into ethyl acetate and was subjected to activity guided purification by column chromatography, TLC and HPLC methods. The pure compound was eluted with retention time of 6.8 min and subjected to 1H, 13C NMR and Mass spectral analysis. The acquired data was compared with that in natural products data base, and was found to be a known antibiotic, reductiomycin. The purified compound showed activity against 5 linezolid resistant cultures and on Mycobacterium tuberculosis. This compound is also showing mild anti cancer activity and is biologically permeable as per Lipinksi's rule.

Preparation, characterization, and in vivo pharmacodynamic evaluation of parenteral diclofenac submicron lipid emulsions.

The aim of the present study was to develop stable parenteral submicron lipid emulsions (SLEs) for sustained delivery of diclofenac acid, used to treat arthritic conditions, to minimize dosing frequency. The SLEs of diclofenac acid were prepared using soybean oil, egg lecithin, and cholesterol. They were heated and processed by homogenization and ultrasonication. The influence of formulation variables, such as the change in proportion of oil and cholesterol, were studied, and optimized formulations were developed. The stability of the optimized formulations SM-A (no cholesterol), SM-I (0.05% cholesterol), and SM-II (0.1% cholesterol) was studied during autoclaving, centrifugal stress, desorption stress (dilution effect), and on storage. The creaming volume percentage was found during the storage and centrifugal stress studies. The effect of dilution on zeta potential and size was noted in the desorption studies. The total drug content and entrapment efficiency was determined using high-performance liquid chromatography. In vitro release studies were performed in phosphate buffer using dialysis method for 12 h. The in vivo anti-inflammatory activity (reduction in paw volume of optimized SLEs) was tested in a 1% carrageenan-induced rat paw oedema model and compared with a diclofenac injection (Voveran). Stable SLEs of diclofenac were developed with a mean size ranging from 200-250 nm and a zeta potential of -31 +/- 1 mV. The cholesterol concentration did not significantly affect the prepared SLEs' size and zeta potential. The optimized formulations, SM-A, SM-I, and SM-II, were relatively stable during centrifugal stress, dilution stress, and storage. The drug content was found to be 2.45 +/- 0.26 mg/mL for SM-A, 2.46 +/- 0.34 mg/mL for SM-I, and 2.42 +/- 0.01 mg/mL for SM-II. The entrapment efficiency was 98.91 +/- 0.13%, 99.01 +/- 0.12%, and 99.27 +/- 0.1% for SM-A, SM-I and SM-II, respectively. The in vitro drug release was zero-order and the cumulative amount of drug released within 12 h was 80% (SM-A), 57% (SM-I), and 42% (SM-II. During in vivo studies, the optimized formulations initially revealed a sustained anti-inflammatory activity occurring up to 12 h, with a maximum activity occurring after 2 h. In the case of the diclofenac injection, the maximum activity persisted up to 5 h and then gradually decreased. No such decrease was noticed regarding the optimized formulations for a period extending up to 12 h. Beyond 12 h, activity persisted up to 24 h with a slight reduction in effect.

Improvement of Anti-Hyperlipidemic Activity and Oral Bioavailability of Fluvastatin Via Solid Self-Microemulsifying Systems and Comparative with Liquisolid Formulation.

BACKGROUND: FR&D scientists continuously try to increase the in vivo performance of low soluble and bioavailable drugs. Solid SMEDDS and liquisolid formulations are relatively simple to develop and fall within the novel drug delivery approaches. Here, a comparison is made to know relative superiority. OBJECTIVE: The study aimed to conduct comparative pharmacokinetic (PK) and pharmacodynamic (PD) studies of developed Fluvastatin (FLU) solid SMEDDS (SSMED) and liquisolid formulation (LS) for their relative in vivo efficacy. METHOD: FLU liquid SMEDDS were optimized by central composite design (CCD). Components, oil, surfactant and co-surfactant were selected as variables; particle size, self-emulsifying time and % drug release in 15min were selected as responses. L-SMEDDS with positive charge inducer were adsorbed on to porous carriers and characterized. Liquisolid formulations were prepared with Avicel PH-102 and Neusilin US2 as carriers. RESULTS: Optimized L-SMEDDS contained 24.92 mg of oil, 45.18 mg of surfactant and 34.28 mg of cosurfactant. SSMEDs containing Syloid XDP (SSMED-XDP) as carrier was selected based on flow properties and liquid retention potential. The average particle size of SSMED-XDP was 154.30±1.10 nm, PDI was 0.311±0.03 and ZP was +19.57±1.34 mV after dilution. The drug release from SSMEDXDP and LS formulations was higher than FLU powder. The bioavailability of SSMEDs was increased by 3.00 fold and that of LS by 1.49 fold more than FLU-suspension. SSMEDs showed 12 h, while LS and suspension showed only 6 h lipid-lowering effect. CONCLUSION: The development of solid SMEDDS resulted in superior performance in both PK and PD effects over the LS formulation.

Development and evaluation of nitrendipine loaded solid lipid nanoparticles: influence of wax and glyceride lipids on plasma pharmacokinetics.

Nitrendipine is an antihypertensive drug with poor oral bioavailability ranging from 10 to 20% due to the first pass metabolism. For improving the oral bioavailability of nitrendipine, nitrendipine loaded solid lipid nanoparticles have been developed using triglyceride (tripalmitin), monoglyceride (glyceryl monostearate) and wax (cetyl palmitate). Poloxamer 188 was used as surfactant. Hot homogenization of melted lipids and aqueous phase followed by ultrasonication at temperature above the melting point of lipid was used to prepare SLN dispersions. SLN were characterized for particle size, zeta potential, entrapment efficiency and crystallinity of lipid and drug. In vitro release studies were performed in phosphate buffer of pH 6.8 using Franz diffusion cell. Pharmacokinetics of nitrendipine loaded solid lipid nanoparticles after intraduodenal administration to conscious male Wistar rats was studied. Bioavailability of nitrendipine was increased three- to four-fold after intraduodenal administration compared to that of nitrendipine suspension. The obtained results are indicative of solid lipid nanoparticles as carriers for improving the bioavailability of lipophilic drugs such as nitrendipine by minimizing first pass metabolism.

Folate-PEG-decorated docetaxel lipid nanoemulsion for improved antitumor activity.

AIM: To develop a folate-based docetaxel lipid nanoemulsion (FLNE) for tumor-targeted treatment. MATERIALS & METHODS: The docetaxel LNEs were prepared and characterized. In vitro cytotoxic and cell uptake studies were performed. The tissue distribution and targeting of drug were studied by fluorescence imaging and tumor regression in mice. RESULTS: The IC50 values of FLNE on cancer cells were significant. The cell uptake studies showed an increase in fluorescence with time. Imaging studies found that FLNE was superior in tumor targeting by 4.81- and 2.08-fold over controls. The tumor regression proved the superiority of FLNEs. CONCLUSION: The folate strategy was superior over PEGylation, albumin and transferrin strategies. The study demonstrated great potential of FLNE as a prospective targeted delivery system.

Albumin anchored docetaxel lipid nanoemulsion for improved targeting efficiency - preparation, characterization, cytotoxic, antitumor and in vivo imaging studies.

The aim was to develop albumin anchored docetaxel lipid nanoemulsion (ALNE) for improving tumor targeted delivery. The O/W lipid nanoemulsion, LNEs were prepared by homogenization and ultrasonication processes. The size of globules and zeta potential were measured by Malvern Zetasizer. Albumin was coupled to stearylamine containing lipid nanoemulsion (SALNE) globules using water soluble EDC reaction. The drug content and entrapment efficiencies for the LNEs were determined by the high-performance liquid chromatography. The in vitro cytotoxic studies of the delivery systems were performed on MCF-7 and Hela cells. The IC 50 values of ALNE on both the cell lines were statistically significant. The in vivo antitumor activity was tested on solid tumors induced in C57BL/6 mice. This study revealed that the percentage tumor inhibition for the groups treated with DLNE, SALNE and ALNE when compared with untreated control was found to be 55.62 ± 5.41%, 54.27 ± 4.85% and 80.01 ± 2.74%, respectively. Furthermore, in vivo distribution studies were carried out in breast cancer MDA-MB231 xenografted Balb/c mice. The LNEs were loaded with fluorescent DiD oil and the distribution in different organs after 6 h was tracked using Caliper life sciences in vivo imaging system. The studies revealed that ALNE was superior in tumor targeting activity when compared with DLNE and SALNE by 3.04 and 2.26 folds, respectively. The average radiance values of ALNE on the tumor tissue were statistically significant when compared with DLNE, SALNE at p < 0.01. In addition, this strategy can become a platform technology for other lipophilic drugs to target tumors.

Brain delivery of transferrin coupled indinavir submicron lipid emulsions--pharmacokinetics and tissue distribution.

Indinavir, an antiretroviral protease inhibitor used in treatment of HIV infection has limited penetration into brain due to efflux of P-glycoprotein. The aim of this work was to develop transferrin coupled submicron lipid emulsions (SLEs) containing indinavir for delivery to brain. Stearylamine containing SLEs were prepared, characterized, tested for stability and optimized formulation (SLE-4) was developed. Transferrin was coupled to get SLE-6 by water soluble EDC method and purified by gel filtration. The coupled transferrin was quantified by modified Bradford dye assay method. The fluorescent dye (DiD oil) incorporated SLEs were used to check the brain specific delivery of SLEs. The in vivo pharmacokinetic and tissue distribution were conducted in mice. During pharmacokinetic studies, there was no significant difference in the serum levels of indinavir from SLE-1, SLE-4 and SLE-6 formulations at all time points. In tissue distribution studies the therapeutic availability (TA) of indinavir in brain from SLE-6 was 4.69, 3.1 and 1.7 times higher than drug solution, SLE-1 and SLE-4 respectively whereas, the TA of indinavir from SLE-4 was 2.76 and 1.82 times the drug solution and SLE-1. The brain to serum ratios with SLE-6 were above one indicates the brain specific delivery. The brain delivery of indinavir was improved with transferrin ligand attachment to SLEs by receptor mediated transcytosis.

Development and in vitro cytotoxic evaluation of parenteral docetaxel lipid nanoemulsions for application in cancer treatment.

The aim of the present study was to develop stable lipid nanoemulsions (LNEs) for delivery of docetaxel for treatment of cancer. The LNEs of docetaxel were prepared by using olive oil and egg lecithin by hot homogenization followed by ultrasonication. The influence of formulation variables such as change in proportion of charge inducers, that is, oleic acid (negative) and stearyl amine (positive), was studied. Stable LNEs of docetaxel having the mean size range of 190-230 nm and zeta potential of -19.2 to -31 mV in the case of oleic acid emulsions and 49.5 to 50.5 mV in the case of stearyl amine emulsions were developed. There was considerable increase in zeta potential value on increasing concentration of oleic acid, whereas no such effect was observed on increasing stearyl amine concentration. During in vitro studies the cumulative amount of docetaxel released from LNE (control emulsion), LNE-O1, LNE-O2, LNE-O3, LNE-S1, LNE-S2, and LNE-S3 was determined. The results indicated that there was no significant effect in varying the concentration of charge inducers on size and in vitro cumulative release of prepared LNEs at 12 h. The optimized formulations were identified as LNE-O3 and LNE-S3 based on relative stabilities during centrifugal stress, dilution stress, and in storage at room temperature. The total drug content and entrapment efficiency of LNE-O3 were found to be 0.96 ± 0.02 mg/mL and 96.35 ± 1.21%, respectively, whereas for LNE-S3 the total drug content and entrapment efficiency were 0.97 ± 0.01 mg/mL and 97.07 ± 0.82%, respectively. During in vitro studies on cancer cell lines both of the optimized formulations, LNE-O3 and LNE-S3, showed similar values of IC50 (half maximal inhibitory concentration) in comparison to docetaxel solution. Based on this, it was concluded that the optimized LNEs were efficacious for the delivery of docetaxel and could act as alternative delivery systems to overcome the poor solubility, hydrolytic instability, and drug-induced and vehicle-related side effects of docetaxel.

Rapid and simple liquid chromatography tandem mass spectrometry method for the quantification of zidovudine in rat plasma.

A high-performance liquid chromatography/electrospray ionization tandem mass spectrometry method was developed and validated for the quantification of zidovudine in rat plasma. Following solid-phase extraction, the analytes were separated using an isocratic mobile phase on a reverse phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M+H]+ ions, m/z 268/127 for zidovudine and m/z 230/112 for the internal standard. The method exhibited a linear dynamic range of 5-500 ng/mL for zidovudine in rat plasma. The lower limit of quantification was 5 ng/mL with a relative standard deviation of less than 8%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 1.5 min for each sample made it possible to analyze more than 400 plasma samples per day. The validated method was applied for pharmacokinetic studies of the novel drug delivery systems of zidovudine in rats.