Poly(n-vinylpyrrolidone) hydrogels: 2.Hydrogel composites as wound dressing for tropical environment

POLY(N-VINYLPYRROLIDONE) HYDROGELS: 2. HYDROGEL COMPOSITES AS WOUND DRESSING FOR TROPICAL ENVIRONMENT. The effects of irradiation on hydration and other properties of poly(vinylpyrrolidone) (PVP) hydrogel composites have been investigated. The aqueous solution of vinylpyrrolidone (VP) 10 wt % was mixed with several additives such as agar and polyethylen glycol (PEG). The solution was then irradiated with gamma rays from Cobalt-60 source at room temperature. Several parameters such as elongation at break (EB), tensile strength (TS), degree of swelling (DS), water vapor transmission rate (WVTR), equilibrium water content (EWC), microbial growth and penetration test, and water activity (Aw) were analysed at room temperature of 29 ±2°C humidity of 80 ± 10%. Results show that elongation at break of hydrogel membranes with initial composition of VP with agar, VP with agar and PEG were 240 % and 250 % kGy, the equilibrium water content of membranes were 96 to 90%, whereas degree of swelling were 55 to 10. The WVTR of hydrogel membranes with initial composition of VP with agar and PEG was 70 g m^-2h^-1, while the water activity was 0.9. Such hydrogel membranes exhibits the following properties: They are elastic, transparent, flexible, impermeable for bacteria. They absopt a high capacity of water, attached to healthy skin but not to the wound and they are easy to remove. These properties of the hydrogel membranes allow for applying as a wound dressings in tropical environment.     

Poly(N-vinylpyrrolidone) hydrogels: 1.Radiation polymerization and crosslinking of N-vinylpyrrolidone

POLY(N-VINYLPYRROLIDONE) HYDROGELS: 1 RADIATION POLYMERIZATION AND CROSSLINKING OF N-VINYLPYRROLIDONE). The effects of irradiation dose on the conversion of vinylpyrrolidone (VP) with various concentration and other characteristics such as Gelation Dose (Dg), Degree of Swelling (DS) and Equilibrium Water Content (EWC) have been investigated. Aqueous solution of vinylpyrrolidone with several concentrations such as 5, 10, 20, 40, 60, 80 and 100 Wt % were irradiated by using gamma rays of Cobalt-60 source with a dose rate of 0. 139 Gy/s. After irradiation, parameters such as conversion of vinylpyrrolidone, gelation dose, degree of swelling, and equilibrium water content were analyzed. Results show that the conversion of VP to PVP was almost 100% at a dose of 2 kGy. The gelation dose of PVP depends on initial content of monomer. Degree of swelling of gels with concentration of 10 % was 55 at the dose of 10 kGy and 30 at the dose of 40 kGy. The lowest value of degree of swelling is 15. At the range of irradiation dose of 10 to 40 kGy the EWC of gel was found to be 98 to 94 %.     

Development and Validation of an RP–LC–UV Method for the Determination of Ondansetron: Application to Pharmaceutical Dosage Forms

A new, simple, rapid, sensitive and specific isocratic RP–LC–UV method was developed and validated for the determination of ondansetron in pharmaceutical dosage forms of orally disintegrating tablets, oral solution and injection. The LC separation was achieved on a Hypersil C4 column (250 × 4.6 mm, 5 μm) using a mobile phase of 50 mM potassium dihydrogen phosphate anhydrous adjusted to pH 3.5 with orthophosphoric acid and acetonitrile (30:70, v/v) at a flow rate of 1.0 mL min^?1 and UV detection at 310 nm. The method was validated for specificity, linearity, precision, accuracy, limit of quantification, limit of detection, robustness and solution stability. The calibration curve was linear over a concentration range of 100–1,000 ng mL^?1 (r ²  = 0.9996) with limit of detection and limit of quantification 50 and 100 ng mL^?1, respectively. The intra-day and inter-day precision and accuracy were between 0.79 and 2.37% and ?0.64 and 1.65%, respectively. The method was successfully applied for analysis of ondansetron in the presence of excipients in commercially available pharmaceutical dosage forms.     

Characterization of poly(vinyl alcohol) hydrogel for prosthetic intervertebral disc nucleus

In the recent years, development of intervertebral disc prosthesis has been of great concern to the world of medicine and science. Substitution of the spinal disc or its part being displaced or damaged due to trauma or a disease process for the artificial structure well imitating high tensile properties and elasticity of the real disc would highly improve the existing treatment techniques. In this work, the attempt to develop the PVA-based hydrogel material for artificial spinal disc has been made. The polymer was initially processed with the use of formaldehyde solution as a crosslinking agent and sulfuric acid as a catalyst. Then properties of the material have been altered by saturating the already existing PVA hydrogel with a mixture of hydrophilic and hydrophobic monomers (2-hydroxyethyl methacrylate and methyl methacrylate) and a subsequent exposure to ionizing radiation (⁶⁰Co source). In this way, interpenetrating polymer network has been built on the crosslinked PVA scaffold. Resulting structures were tested for their mechanical behavior at different loads. Series of measurements leading to the determination of the physicochemical properties of created gels including crosslink density and swelling abilities were also performed.     

Crosslinking of poly(-caprolactone) by radiation technique and its biodegradability

Poly(-caprolactone), PCL, (melting temperature, 60°C) was gamma-irradiated in the solid state at 30–55°C, the molten state, and the supercooled state (irradiation at 45–55°C after melting, 80°C) under vacuum to improve its heat resistance. Irradiation of PCL in the supercooled state led to the highest gel content and this polymer has high heat resistance. On the other hand, relatively smaller doses such as 15 and 30 kGy were effective to improve processability of PCL by formation of branch structure during irradiation.     

Development and Validation of an HPLC–UV Method for the Determination of Insulin in Rat Plasma: Application to Pharmacokinetic Study

A simple, sensitive high performance liquid chromatographic method with UV detection was developed and validated for determination of insulin in rat plasma, using methyl paraben as an internal standard. Insulin was extracted from plasma by a liquid–liquid extraction with a mixture of dichloromethane and n-hexane (1:1, v/v) followed by an acidic back extraction. Chromatographic separation was achieved isocratically with a Phenomenex® C₁₈ analytical column (150 × 4.6 mm ID, 5 μm) at ambient room temperature. The calibration curves were linear within a concentration range of 0.7–8.4 μg mL^?1 (r ² = 0.9994). The inter-day and intra-day accuracy and precision were ≤3.33 and ≤5.55%. The limit of detection (LOD) and limit of quantification (LOQ) were 0.35 and 0.7 μg mL^?1. The average recovery was 87.86% for insulin and 83.52% for methyl paraben. Insulin containing plasma samples were stable at ?20 °C for 7 days. Validated HPLC method was successfully applied to a pharmacokinetic study of insulin in streptozotocin induced diabetic rats.     

Formulation and optimization of orally disintegrating tablets of sumatriptan succinate

The aims of the present research were to mask the intensely bitter taste of sumatriptan succinate and to formulate orally disintegrating tablets (ODTs) of the taste masked drug. Taste masking was performed by coating sumatriptan succinate with Eudragit EPO using spray drying technique. The resultant microspheres were evaluated for thermal analysis, yield, particle size, entrapment efficiency and in vitro taste masking. The tablets were formulated by mixing the taste masked microspheres with different types and concentrations of superdisintegrants and compressed using direct compression method followed by sublimation technique. The prepared tablets were evaluated for weight variation, thickness, hardness, friability, drug content, water content, in vitro disintegration time and in vitro drug release. All the tablet formulations disintegrated in vitro within 37-410 s. The optimized formulation containing 5% Kollidon CL-SF released more than 90% of the drug within 15 min and the release was comparable to that of commercial product (Suminat?). In human volunteers, the optimized formulation was found to have a pleasant taste and mouth feel and disintegrated in the oral cavity within 41 s. The optimized formulation was found to be stable and bioequivalent with Suminat?.