Effect Of Hydrophilic Polymers Research Articles

Effect of hydrophilic polymers on the release of diltiazem hydrochloride from elementary osmotic pumps

Diltiazem hydrochloride (DLTZ) is a freely water-soluble drug, because of its higher aqueous solubility, the suitability of the drug with elementary osmotic pumps is restricted. Plain DLTZ elementary osmotic pump had shown higher release rate. Drug entrapment in polymer matrix or addition of release retardant materials (various polymers) can reduce the release rate of drug. In present study, effect of appropriate hydrophilic polymers (HP) on the release pattern was investigated. Ingredients of the system were optimized for parameters like drug:polymer ratio and amount of osmogent, for the desired release pattern. Two optimized formulations were selected for further characterization. Theoretical release rate of the formulations were also determined and compared. Different dissolution models were applied to drug release data in order to establish release mechanism and kinetics. Criteria for selecting the most appropriate model were based on best goodness of fit and smallest sum of squared residuals.

Effect of Hydrophilic Polymers on Physical Stability of Liposome Dispersions

Interactions between various hydrophilic polymers and liposomes composed of hydrogenated soybean lecithin were investigated by means of isothermal titration calorimetry (ITC), FT-IR, and dynamic light scattering (DLS) measurements. Their effect on the dispersity of liposomes was investigated by turbidity measurement. Sodium alginate was found to bind to lipid bilayers via electrostatic interaction and to stabilize dispersity over a wide concentration range despite its high hydrophilicity. This was elucidated in terms of the irreversible adsorption of sodium alginate onto the liposome surfaces. Carboxymethyl cellulose sodium salt and poly(vinyl alcohol) gave similar results, but the stabilization effect was reduced. Other polymers, which were adsorbed onto the liposome surfaces very weakly or not adsorbed at all, destabilized the dispersity significantly, just below the overlap concentration of polymers. This was interpreted in terms of depletion flocculation. The adsorption of the polymers onto the liposome surfaces was detected by ITC and DLS measurements, although the adsorbed fraction seemed to be very small. Notably, ITC enabled us to quantitatively estimate the heat flow accompanied by the adsorption. The sign of the heat flow due to the adsorption enabled us to detect the perturbation of the lipid membrane, which was also proved by FT-IR measurements. The relationship between the interaction strength and the stabilization effect is discussed.

Effect of several hydrophilic polymers on the permeation of morphine and salicylic acid through excised hairless rat skin.

Several hydrophilic polymers changed the cumulative amount of morphine (MOR) permeated through excised hairless rat skin from 1% MOR hydrochloride solution containing ethanol and l-menthol at concentrations of 40% and 5%, respectively, as permeation enhancers. Anionic polymers (carboxyvinylpolymer and methylvinylether-maleic anhydride copolymer) in the test solutions decreased the skin permeation of MOR, whereas cationic polymers (polyethyleneimine and chitosan) increased it, compared with that without polymers. Little change, however, was observed by the addition of nonionic polymers (hydroxypropylcellulose and polyethyleneoxide). On the other hand, the cationic and anionic polymers in the test solutions decreased and increased, respectively, the skin permeation of salicylic acid (SA) from the same enhancing system containing sodium salicylate. These opposite results were probably caused by the change in escaping tendency of the drugs from the vehicles, which was due to the drug-polymer interaction. (The escaping tendency has a great effect on the drug partition from the polymer solution to the skin barrier). The effect of hydrophilic polymers on the partition was then evaluated by Donnan membrane theory. The partition of MOR was increased and decreased by the presence of polymers having identical and opposite charge to MOR. The low partition of the drugs to skin may also be caused by low diffusion of the drugs in the polymer solutions. The drug release from the hydrophilic polymer solutions was then measured, and the release rate was found to have decreased in the presence of polymers having opposite charge to MOR and SA. It is suggested that these drug-polymer interactions changed the drug partition to skin thus changing the skin permeation of the drug.

THE EFFECT OF HYDROPHILIC POLYACRYLAMIDE GELS ON ESTABLISHMENT OF WOODY PLANTS UNDER DROUGHTED AND SALINE CONDITIONS

Summary The effect of hydrophilic polymers on newly planted trees and shrubs is one of the most confused areas of establishment research, with many papers reporting benefits where others show no effect or even suggest that the polymers may be harmful. Trials were carried out to try to identify the potential causes of such variation. To minimise genetic variation two cultivars of shrubs were compared Deutzia scabra Thunb. ‘Pride of Rochester’ and Ligustrum ovalifolium Hassk. ‘Aureum’. These were planted as liners either in containers or directly into sandy loam soil. Both growing media were amended with the rates of 0, 1, 1.5, 1.75 g l−1 dry polymer. The container plants underwent a controlled watering regime in a polythene tunnel and were only watered when wilting became apparent. Watering frequency, pot weight at field capacity, total water demand and also leaf numbers and plant heights were recorded over the time of the experiment. The leaf area, root dry weights and shoot dry weights were recorded at t...

The Effect of Hydrophilic Polymer on Media Water Retention and Nutrient Availability to Ligustrum lucidum

Abstract Ligustrum lucidum Ait. ‘Compaction’ grown in hydrophilic polymer-amended medium required irrigation less frequently than plants in nonamended medium. Plants contained higher levels of N and K and lower levels of Ca, Mg, and other divalent cations when grown in polymer-amended medium, as compared to controls. Polymer was associated with maintenance of higher pH. With an osmocote rate increase from 15 to 45 g, a polymer × fertilizer interaction was observed. Dry weights of polymer-treated plants decreased and controls increased with increasing fertility.

The effect of hydrophilic polymers and surface active agents on the solubility of indomethacin

This work examines the effect of two surfactants: sodium lauryl sulphate (SLS) and polysorbate 80, and two hydrophilic polymers: polyethylene glycol (PEG 6000) and polyvinylpyrrolidone (PVP) on the aqueous solubility of indomethacin. It is found that all the above solubilizing agents increase the solubility of the drug in the following order: SLS > polysorbate 80 > PEG 6000 > PVP. The work also includes calculation of some thermodynamic functions such as the heat of solution (ΔH) and the free energy change (itΔG). In addition the solvent power of the PEG 400/water system is determined. The number of indomethacin molecules bound to a molecule of PEG is calculated and an equation describing this binding process is proposed.

The effect of hydrophilic polymers on the electrophoretc mobility of suspended particles

The effects of various grades of polyvinylpyrrolidone (PVP), sodium carboxymethyl-cellulose (SCMC), acid and alkaline gelatins and hydroxypropylmethylcellulose (HPMC) on the electrophoretic mobility of polystyrene latex, and particles of the drugs, nystatin and sulphadimidine, have been examined. In all cases, particle mobility was influenced by the adsorbed polymer molecules with the observed effect being dependent on polymer type, grade and concentration. The non-ionic polymer, PVP, resulted in an appreciable decrease in particle mobility, the effect being greater for the higher molecular weight fractions. However, with the anionic polymer, SCMC, the mobility of particles was controlled by the ionization of the polymer carboxylic groups. The effect of adsorbed gelatin on particle mobility was dependent upon the ionization of the amino acid groups and thus enabled the isoelectric point of the gelatins to be determined from pH-particle mobility plots. HPMC adsorption resulted in a low negative mobility which was independent of PH.

Effects of hydrophilic polymers on the viability and growth of soybean cells in culture: The use of polymers as cryoflxatives for plant tissue

Effects of hydrophilic polymers on the viability and growth of soybean cells in culture: The use of polymers as cryoflxatives for plant tissue