PLGA/PEG-derivative polymeric matrix for drug delivery system applications: Characterization and cell viability studies.

The incorporation of additives such as polyoxyethylated oleic acid glycerides (PEG-derivative) can modify the release of drugs from microparticles. PEG-derivative decreases the release rate of drugs that are dissolved in PLGA matrices but if un-dissolved the initial release rate slightly increases. To clarify this behaviour the influence of adding PEG-derivative in the preparation of microspheres was investigated by scanning electron microscopy, differential scanning calorimetry, gel permeation chromatography, nuclear magnetic resonance and infrared spectroscopy. Cytotoxicity of this resulting PLGA/PEG-derivative matrix was evaluated in cell lines (fibroblasts) which are more reproducible but less specific and in primary cell cultures (splenocytes and human leucocytes) which have the advantage of their specificity. Scanning electron microscopy revealed that PLGA/PEG-derivative microspheres exhibited small surface concavities with a highly porous polymeric matrix. The incorporation of PEG-derivative caused a slight reduction in the T(g) values of PLGA. In vitro degradation studies showed that PEG-derivative remains within the microspheres as long as the matrix does. This PLGA/PEG-derivative matrix was well tolerated exhibiting cell viabilities similar to PLGA microspheres and can be used to modulate the release of drugs from microparticulate systems destined for parenteral administration.

Morphine, haloperidol and hyoscine N-butyl bromide combined in s.c. infusion solutions: compatibility and stability. Evaluation in terminal oncology patients.

The administration of drugs by subcutaneous infusion is routinely practiced in palliative medicine for the management of patients who are no longer able to take oral medication. It is common for two or more drugs to be combined in subcutaneous solutions. The combination of an opioid with other drugs (haloperiol lactate and hyoscine N-butyl bromide) can be very valuable. Unfortunately, the compatibility and stability of morphine hydrochloride, haloperidol lactate and hyoscine N-butyl bromide combined in the same solution has not yet been determined. Therefore, this study examined the stability of ternary solutions containing morphine HCl, haloperidol lactate and hyoscine N-butyl bromide at different dose ranges. Twelve different solutions were assessed for 15 days after preparation in polypropylene syringes using 0.9% saline as diluent. Triplicate syringes were stored at 25 degrees C. HPLC was the analytical technique used to measure morphine HCl, haloperidol lactate and hyoscine N-butyl bromide. Initial concentration ranges were 1.67-10.0 mg/ml for morphine HCl, 0.417-0.625 mg/ml for haloperidol lactate and, 5.0-6.67 mg/ml for hyoscine N-butyl bromide. All three drugs were very stable (>92.5%) when stored at 25 degrees C. The clinical performance of the admixture was retrospectively assessed in 21 terminal oncology patients. Total symptom control was achieved in 17 out of 21 patients with very good local tolerance.

HPLC-UV method development and validation for the quantification of ropinirole in new PLGA multiparticulate systems: Microspheres and nanoparticles.

A simple HPLC-UV method was developed and validated for the quantitation of RP free base encapsulated into two new multiparticulate systems (microparticles and nanoparticles), as well as for the quantification of RP hydrochloride when given as a loading dose together with the new delivery system developed. HPLC separation was achieved using a C18 Kromasil column (250 mm × 4 mm) with a mobile phase composed of acetonitrile-phosphate buffer solution (55:45, v/v) adjusted at pH 6.0 and containing 0.3% triethanolamine. Flow rate was set at 1.0 mL min(-1). The UV detector was operated at 245 nm. The method allowed for the simultaneous determination of both RP and RP-HCl. The method was linear within the range 2.5-50 µg mL(-1) for both RP and RP-HCl. The limits of detection (LOD) and quantitation (LOQ) found were 0.8 µg mL(-1) and 2.4 µg mL(-1) for RP, and 0.3 µg mL(-1) and 0.9 µg mL(-1) for RP-HCl. The method was found to be simple, rapid, specific, precise, accurate, and reproducible. The method was successfully applied to the determination of the encapsulation efficiency of RP in the multiparticulate systems developed, being 85.03 ± 3.77% and 51.12 ± 3.50%, for RP-loaded PLGA microspheres and RP-loaded PLGA nanoparticles, respectively.

Estimation of the rate constants in a data-sparse environment: comparison of a mathematical method and least squares analysis.

A new method is presented for estimating the rate constants for the one-compartment open model with first-order absorption in a data-sparse environment. It is based on the principles of matrix algebra and system theory and requires only three to four plasma samples drawn at equal time intervals (a minimum of at least one sample in the absorption phase and one sample in the elimination phase). The utility of the technique is illustrated by comparing the parameter estimates from the matrix method with the estimates from a nonlinear computer parameter estimation program. In the preliminary evaluation of the method with both perfect data and data with randomly distributed error, the parameter estimates from the matrix method proved to be as good as the computer estimation for data-sparse systems. In a more realistic comparison with published patient data, the matrix method resulted in 0 to 456% better estimates of kel and ka than the computer estimation. Since the matrix method is mathematically simple and requires only three to four blood samples, it should prove very useful in data-sparse systems (e.g., clinical or small animal situations) where a minimum amount of blood samples can be drawn.

Comparative study of the dissolution profiles of a commercial theophylline product after storage.

The purpose of this work was to study the effect of storage time and temperature on the in vitro release kinetics of a commercial sustained-release dosage form of theophylline, at different pHs of the dissolution medium. The formulation was stored at 35 degrees C for 16 months and at 45 degrees C for 8 months, with a relative humidity of 60%. The in vitro release tests were performed at pHs 2, 4, 6 and 7.4. The mean values of the transport coefficient n, were close to 0.5 in all the conditions tested, which indicates that the transport system is not modified after storage of the formulation at 35 degrees C and 45 degrees C. The mean values of the dissolution rate constant ranged from 0.036 to 0.043 min(-n), under all the conditions tested. Significant differences (alpha = 0.05) were found between pHs 2, 4 and 6, 7.4 for all the model-independent parameters studied. When the formulation was kept at 35 degrees C for 16 months, the mean percentage of drug dissolved at 8 hours was 25.61% (pHs 2, 4) and, 36.12% (pHs 6, 7.4), representing a 26% and 24% reduction, respectively. Similar results were obtained after storing the formulation at 45 degrees C for 8 months, corresponding to 33.3% (pHs 2, 4) and, 22.5% (pHs 6, 7.4) diminution, respectively. The values of the similarity factor, f2, obtained were lower than 50, which indicates the lack of similarity among the dissolution profiles, after storing the formulation under the experimental conditions tested.

Pharmacokinetic study of etodolac after rectal administration; "in vitro" release kinetics.

The present study describes the pharmacokinetic behaviour of a new dosage form of etodolac not available in the Spanish market: suppositories. Rectal administration was chosen as an alternative for the oral route. The dose used was 200 mg. The pharmacokinetic parameters of the drug are estimated by means of two possible methods i.e., model-independent and model-dependent. The results obtained are compared and discussed. At the same time, an "in vitro" study of the release kinetics of etodolac from the suppository was performed using a continuous flow system without fluid recirculation or accumulating reservoir. The dissolution media used were buffered aqueous solutions at pH 6.5 and 7.4. The results obtained show that the release of the drug from the supposity could be a limiting factor for its absorption.

Dissolution rate and in situ intestinal absorption kinetics of guanyl-cysteine.

The study of the dissolution behaviour of guanyl-cysteine is presented. The drug was assayed as a pure non-formulated product and formulated in hard gelatine capsules. Aqueous solutions buffered at different pH were used as dissolution fluids. The dissolution rate constant of the drug in this formulation was estimated. Our results show that dissolution of guanyl-cysteine occurs very rapidly. As pH of the dissolution fluid increases, the rate constant slightly decreases. The study of the absorption kinetics of guanyl-cysteine from small intestine of rats was performed with the experimental technique proposed by Doluisio. Six different concentrations of the drug were assayed for the estimation of the absorption rate constant of guanyl-cysteine under our experimental conditions. Our results show that intestinal absorption of the drug occurs as a first-order process.

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.

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.

Protective effects of clioquinol on human neuronal-like cells: a new formulation of clioquinol-loaded PLGA microspheres for Alzheimer's disease.

BACKGROUND: Clioquinol (CQ), a metal chelator, has gained renewed attention due to its ability to modulate metal homeostasis in neurodegenerative disorders such as Alzheimer's disease. PURPOSE: To investigate the protective effects of a wide range of concentrations of CQ on two human neuroblastoma cell lines (IMR-32 and SKN-AS) and to develop and characterize a new controlled release system of CQ consisting of biodegradable microspheres. RESULTS: H(2)O(2) (400 µM) adequately induced death cell in IMR-32 and SKN-AS cell lines thereby resulting in a useful model for neuroprotective studies. CQ (20-50 µM) induced a potent and robust protective effect against peroxide-mediated oxidative stress in human neuronal-like cells (SKN-AS) determined by both MTT and flow cytometry (cell viability). These results were also confirmed by means of reactive oxygen species (ROS) production. Biodegradable poly(dl-lactic-co-glycolic acid) (PLGA) resomers assayed for microspheres preparation were PLGA-502 and PLGA-502H. Optimization by using an experimental design resulted in a formulation prepared with CQ (112 mg) and PLGA-502H (400 mg). With this formulation, mean encapsulation efficiency of 82.37% ± 6.67% and, zero-order release rate of 58 ± 3µg CQ/day/10 mg microspheres between Days 10 and 35 were obtained. CONCLUSION: We have developed a promising formulation for the treatment of Alzheimer's disease.

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. OBJECTIVE: To study the compatibility and stability of tramadol hydrochloride and dexamethasone sodium phosphate combined in solution and to report on its use in terminally ill patients. METHOD: Twelve different solutions containing tramadol hydrochloride (8.33-33.33 mg/mL) and dexamethasone sodium phosphate (0.33-3.33 mg/mL) were prepared in saline and stored in polypropylene syringes for 5 days (25 degrees C). Analysis was performed on days 1, 3 and 5 days with simultaneous determination by HPLC. pH was measured at 0 and 5 days. Clinical performance was assessed retrospectively in six terminal-ill oncology patients. RESULTS: Maximum losses of 7% and 6% were observed for tramadol and dexamethasone. Pain was completely controlled in four patients. Local tolerance resulted in haematoma in three patients, which resolved by switching to a butterfly insertion site. CONCLUSION: Tramadol hydrochloride (100-400 mg/day) and dexamethasone sodium phosphate (4-40 mg/day) are stable for at least 5 days when combined in saline and stored at 25 degrees C. These results are only valid for the type of syringes and the specific commercial preparations tested.

Interactions of anti-infectives: a review.

Drug interactions can be beneficial and valuable, but their consequences are usually adverse/undesirable, thus compromising the efficacy of drugs and enhancing their toxicity. Interactions can be divided into pharmaceutical incompatibilities, and pharmacokinetic and pharmacodynamic interactions. Unexpected drug responses can result from drug-excipient incompatibilities or erroneous technological processes. Pharmacokinetic interactions can affect the processes of drug absorption, distribution, metabolization and excretion. Pharmacodynamic interactions occur when the effects of one drug are changed by the presence of another drug at its site of action; such interactions are classified as synergistic and antagonistic. The clinically most relevant drug interactions following this classification and regarding the use of anti-infectives are reviewed. Knowledge, research and discussion of drug interactions will assist in giving the patient optimal care.

[Radio-anatomic study of the median artery]. / Etude radio-anatomique de l'artère médiane.

A study of the median artery has been done on 40 forearms, using anatomical and radiological methods. Of the points studied, the following are of particular interest: the mode of origin and the systematization of the various types.

[Interkinetic nuclear migration in nasal placode of chick embryo]. / Migration intercinétique dans la placode olfactive chez l'embryon de poulet.

Cells of nasal placode of chick embryos were studied with thymidine H3 and autoradiography. Our results shown, that the nuclei in the nasal placode synthesize DNA in the outer zone, then migrate toward the inner zone to undergo division and subsequently return to the outer zone.

[Interkinetic migration of the auditory placode in the chick embryo]. / Migration intercinétique dans la placode otique chez l'embryon de poulet.

Interkinetic nuclear migration was studied in cells forming the auditory placode of chick embryos with thymidine H3 and autoradiography. Our results show, that the nuclei in the auditory placode, synthesize D.N.A. in the outer zone, then migrate toward the inner zone to undergo division and subsequently return to the outer zone.

[Ultrastructural study of the olfactory placode in the chick embryo]. / Etude ultrastructurale de la placode olfactive chez l'embryon de poulet.

An ultrastructural study of the nasal placode of chick embryos between the stages 16 to 24 of Hamburger-Hamilton was made. The study describes the disposition of the constituent elements as well as their characteristics.