Emilia Barcia

Downregulation of endotoxin-induced uveitis by intravitreal injection of polylactic-glycolic acid (PLGA) microspheres loaded with dexamethasone.

We tested the short- and long-term ability of polylactic-glycolic acid (PLGA) microspheres loaded with dexamethasone to reduce ocular inflammation in rabbits elicited by intravitreal lipopolysaccharide (LPS) injection. PLGA microspheres loaded with dexamethasone were prepared by the solvent evaporation technique from an oil/water emulsion and sterilized by gamma irradiation (25 kGy). The microsphere fraction selected was 2:10 (dexamethasone:PLGA) and contained 141 +/- 0.38 microg dexamethasone/mg PLGA. Microsphere diameters were 20-53 microm, and the mean encapsulation efficiency was 92.97 +/- 0.75%. Seven days prior to the induction of panuveitis, 10 mg of dexamethasone-free or dexamethasone-loaded microspheres were injected into the vitreous. Control animals received no injection. Panuveitis was induced in male New Zealand rabbits (2.5-3.0 kg) by intravitreal injection of Escherichia coli LPS. Clinical evaluation, electroretinography and histopathologic studies were performed in short-term studies of 15 days and in long-term studies of 33 days. Efficacy in reducing inflammation was also studied in vitrectomized eyes. In short-term studies eyes injected with dexamethasone-loaded microspheres had less inflammation than control eyes and eyes injected with blank microspheres. Inflammation reverted in all groups by 15 days after LPS injection. A second LPS dose given on Day 30 provoked a high peak of inflammation in control eyes and in those injected with blank microspheres. In contrast, only slight inflammation occurred in eyes injected with dexamethasone-loaded microspheres. Histopathology and electroretinography supported these results. Dexamethasone-loaded microspheres effectively reduced intraocular inflammation caused by LPS in both short- and long-term studies.

An effective novel delivery strategy of rasagiline for Parkinson's disease.

This is the first report on the efficacy of a new controlled release system developed for rasagiline mesylate (RM) in a rotenone-induced rat model of Parkinsons disease (PD). PLGA microspheres in vitro released RM at a constant rate of 62.3 μg/day for two weeks. Intraperitoneal injection of rotenone (2 mg/kg/day) to Wistar rats produced typical PD symptoms. Catalepsy, akinesia and swim tests outcomes in animals receiving RM either in solution or within microspheres showed a reversal in descent latency when compared to rotenone-treated animals, being this reversal specially pronounced in animals receiving RM microspheres (dose equivalent to 1 mg/kg/day RM injected i.p. every 15 days). Nissl-staining of brain sections showed selective degeneration of the substantia nigra (SNc) dopaminergic neurons in rotenone-treated animals which was markedly reverted by RM microspheres. PET/CT with (18)F-DG resulted in mean increases of accumulation of radiotracer in striatum and SNc of around 40% in animals treated with RM microspheres which also had significant beneficial effects on Bcl-2, Bax, TNF-α mRNA and SOD2 levels as detected by real-time RT-PCR. Our results confirm the robust effect achieved by the new controlled release system developed for RM which exhibited better in vivo efficacy than RM given in solution.

Development and validation of a reverse phase liquid chromatography method for the quantification of rasagiline mesylate in biodegradable PLGA microspheres

In the present study, a reverse phase high performance liquid chromatographic method was developed and validated for the determination of rasagiline mesylate in biodegradable microspheres. Chromatographic separation was carried out on a RP-18 column using a mobile phase consisting of acetonitrile:water (5:95, v/v) adjusted at pH 3.1. Flow rate was 1.0 ml min(-1) and UV detection at 290 nm. Acyclovir was used as the internal standard. The calibration curve was linear over the range 0.5-20.0 microg ml(-1). R.S.D. for precision was <1.8%. Accuracy ranged between 99.01% and 102.55% with a R.S.D. lower than 1.3%. LOD and LOQ were 0.07 microg ml(-1) and 0.23 microg ml(-1), respectively. The method was simple, rapid, and easy to apply, making it very suitable for routine analysis of rasagiline mesylate in biodegradable PLGA microspheres. It could be also used with reliability for the determination of the drug in other pharmaceutical dosage forms.

PEG-derivative effectively modifies the characteristics of indomethacin-PLGA microspheres destined to intra-articular administration.

The aim of this study was to obtain biodegradable indomethacin microspheres for intra-articular administration in rheumatoid arthritis, where angiogenic processes are involved. Indomethacin concentrations to achieve an anti-angiogenic effect would be five-times higher than an anti-inflammatory. Microspheres were prepared by solvent evaporation using PLGA. Indomethacin is a poor water-soluble drug with it being possible that dissolved and non-dissolved drug co-exist within the polymeric matrix resulting in rapid release. To control this release, an oil-PEG-derivative was incorporated, producing changes in morphology, crystallinity and indomethacin release. To minimize the amount of microspheres administered, a two-factor five-level central rotable composite 22 + star design was employed with two independent variables: indomethacin percentage and PEG-derivative percentage. The optimum formulation showed mean encapsulation efficiency of 94.3 ± 2.2% and released 7.99 ± 0.25 µg indomethacin/day/mg microspheres for 21 days. A dose of 20–50 mg of this formulation could be appropriate to achieve both anti-angiogenic and anti-inflammatory effects. Preliminary cytotoxicity studies performed in rat splenocytes showed an adequate cell viability.

Controlled release of rasagiline mesylate promotes neuroprotection in a rotenone-induced advanced model of Parkinson's disease

Microencapsulation of rasagiline mesylate (RM) into PLGA microspheres was performed by method A (O/W emulsion) and method B (W/O/W double emulsion). The best formulation regarding process yield, encapsulation efficiency and in vitro drug release was that prepared with method A, which exhibited constant drug release for two weeks (K(0)=62.3 μg/day/20mg microspheres). Exposure of SKN-AS cells to peroxide-induced oxidative stress (1 mM) resulted in cell apoptosis which was significantly reduced by RM (40.7-102.5 μM) as determined by cell viability, ROS production and DNA fragmentation. Daily doses of rotenone (2 mg/kg) given i.p. to rats for 45 days induced neuronal and behavioral changes similar to those occurring in PD. Once an advanced stage of PD was achieved, animals received RM in saline (1 mg/kg/day) or encapsulated within PLGA microspheres (amount of microspheres equivalent to 15 mg/kg RM given on days 15 and 30). After 45 days RM showed a robust effect on all analytical outcomes evaluated with non-statistically significant differences found between its administration in solution or within microparticles however; with this controlled release system administration of RM could be performed every two weeks thereby making this new therapeutic system an interesting approach for the treatment of PD.

Effective antiproliferative effect of meloxicam on prostate cancer cells: Development of a new controlled release system

Recent studies have shown that COX-2 inhibitors, such as meloxicam, have demonstrated promising results when used with chemotherapy. Based on these findings, this is the first study in which the antiproliferative effect of meloxicam is investigated on two prostate cancer cell lines (PC3 and DU-145). We have also evaluated if this antiproliferative effect is dose- and/or time-dependent. Meloxicam is assayed at a concentration range of 10-800 microM for 24, 48 and 72 h. Our results reveal that meloxicam has a selective dose- and time-dependent antiproliferative effect against PC3 but not against DU-145 cells. In PC3 cells the IC(50) decreased from 740 microM at 24 h to 515 microM at 72 h after meloxicam treatment. Chemoembolization based on microspheres has been emerged as a novel and promising way for antitumoural therapy; therefore, in our study we have developed and characterized a new controlled release system consisting of biodegradable PLGA/PEG-derivative meloxicam microspheres. The optimized formulation has a mean particle size of 13.06+/-0.09 microm, mean encapsulation efficiency of 58.44+/-4.53% and releases 0.45+/-0.05 microg meloxicam/day/mg microspheres between days 3 and 28 of the in vitro release assay. In conclusion, we should consider meloxicam as a possible adjuvant agent in the treatment of prostate cancer.

Compatibility and stability of tramadol and dexamethasone in solution and its use in terminally ill patients.

Background:  Delivery of drug admixtures by continuous subcutaneous infusion is common practice in palliative medicine, but analytical confirmation of their compatibility and stability is not always available.

Cytotoxicity and biocompatibility evaluation of a poly(magnesium acrylate) hydrogel synthesized for drug delivery.

We report the synthesis and characterization as well as cytotoxicity and biocompatibility studies of a poly(magnesium acrylate) hydrogel (PAMgA) developed for drug delivery applications. Two hydrogels with different mesh sizes, large and short, were synthesized (L-C PAMgA and S-C PAMgA). The hydrogels were characterized through swelling, FT-IR and DSC. Cytotoxicity in vitro was evaluated on cell line NIH-3T3 fibroblasts via direct contact and two indirect contact methods (MTT and flow citometry). Both PAMgA hydrogels exhibited low cytotoxicity with survival rates higher than 90%. To select their administration route, biocompatibility was evaluated after intraperitoneal, subcutaneous, and oral administration to mice of both hydrogels at different dose ranges. Swelling percentages obtained were 33.3 ± 4.2% and 166.7 ± 8.3% for L-C PAMgA and S-C PAMgA respectively, showing a great difference in both hydrogels. Among the administration routes assayed, the hydrogels were well tolerated after oral administration of a wide dose range (10-500 mg/kg), thereby indicating that both PAMgA hydrogels are excellent candidates for oral administration due to their in vitro biocompatibility and oral non-toxicity. These results together with the fact that their synthesis is simple and inexpensive make them good candidates for the design of oral drug delivery devices.

Pharmacokinetics of vancomycin and dosing recommendations for trauma patients

OBJECTIVES The objectives of this study were to characterize the population pharmacokinetics of vancomycin in trauma patients and to propose dosing schemes to optimize therapy. PATIENTS AND METHODS Trauma patients from Hospital Universitario Severo Ochoa (Spain) receiving intravenous vancomycin and routine therapeutic drug monitoring were included. Concentrations and time data were retrospectively collected, and population modelling was performed with NONMEM 7.2; internal and external validations were performed to probe the final model. Finally, several simulations were executed to propose dosing guidelines to reach expected vancomycin concentrations. RESULTS A total of 118 trauma patients were included; the population was 45% males, with a mean age of 77 years (range 37-100 years) and a mean total body weight (TBW) of 72 kg (range 38-110 kg). The pharmacokinetics of vancomycin was best described by a two-compartment open model; creatinine clearance (CLCR) was related to vancomycin clearance (0.49 ± 0.04 L/h), being diminished by the presence of furosemide (0.34 ± 0.05 L/h). TBW influenced both the central volume of distribution (V1 = 0.74 ± 0.1 L/kg) and peripheral volume of distribution (V2 = 5.9 ± 2 L/kg), but patients with age >65 years showed a larger V1 (1.07 ± 0.1 L/kg). Bootstrapping was performed to internally validate the stability of the final model. External validation was developed using an alternate population of 40 patients with the same characteristics. The validated model was compared with population pharmacokinetic models previously published and showed better predictive performance for trauma patients than the current one. This final model allowed us to propose a new practical dose guideline to reach higher trough concentrations (15-20 mg/L) and AUC0-24/MIC ratios of more than 400 after 4 days of vancomycin treatment. CONCLUSIONS A new population model was described for trauma patients to optimize vancomycin therapy, showing precise predictive performance to be applied for therapeutic drug monitoring and providing a new practical dose guideline that considers CLCR and concomitant administration of furosemide for these patients.

New celecoxib multiparticulate systems to improve glioblastoma treatment.

Treatment of malignant gliomas consists of resection followed by radiotherapy and chemotherapy. Celecoxib (CXB), a selective COX-2 inhibitor, is able to control inflammation and pain, to improve the efficacy of radiotherapy, and to inhibit at high doses the growth of cancer cells. Two new delivery systems for CXB are developed: microspheres (MPs) for implantation in the brain after partial/complete removal of the tumor, and nanoparticles (NPs) for their potential to cross the blood brain barrier and deliver CXB into the CNS. Cell culture assays performed in PC12, SKN-AS and U373-MG cells demonstrate the antiproliferative affects of CXB, with EC50 values of 99.81 μM and 82.4 μM in U373-MG and SKN-AS cells. Encapsulation efficacy of CXB in formulation MP2 (20% CXB) was 74.6 ± 2.2% with a zero-order release rate of 47.8 μg/day/20mg microspheres for 34 days. Uncoated and polysorbate 80-coated CXB-NPs are prepared by nanoprecipitation. Mean sizes of uncoated and coated CXB-NPs were 173.6 ± 44.9 nm and 100.6 ± 62.1 nm. Cerebral cortex images showed a marked increase of fluorescence when the surfactant-coated NPs were administered to rats. These results suggest that both CXB formulations (MPs and NPs) are adequate systems to enhance the effects of chemotherapy in the treatment of malignant brain tumor.