Improved method to construct an anterior deprogramming device.

Bioadhesive latices of water-swollen poly(acrylic acid) nano-and microparticles were synthesized using an inverse (W/O) emulsion polymerization method. They are stabilized by a co-emulsifier system consisting of SpanTM 80 and TweenTM 80 dispersed in aliphatic hydrocarbons. The initial polymerization medium contains emulsion droplets and inverse micelles which solubilize a part of the monomer solution. The polymerization is initiated by free radicals, and particle dispersions with a narrow size distribution are obtained. The particle size is dependent on the type of radical initiator used. With water-soluble initiators, for example ammonium persulfate, microparticles were obtained in the size range of 1 to 10 micrometer indicating that these microparticles originate from the emulsion droplets since the droplet sizes of the W/O emulsion show similar distribution. When lipophilic radical initiators, such as azobis-isobutyronitrile, are used, almost exclusively nanoparticles are generated with diameters in the range of 80 to 150 nm, due to the limited solubility of oligomeric poly(acrylic acid) chains in the lipophilic continuous phase. These poly(acrylic acid) micro- and nanoparticles yielded excellent bioadhesive properties in an in-vitro assay and may, therefore, be suitable for the encapsulation of peptides and other hydrophilic drugs.

Acrylic Resins↗

PubMed1998

Penetration enhancing effect of tetrahydrogeraniol on the percutaneous absorption of 5-fluorouracil from gels in excised rat skin.

Poly(acrylic acid) gels containing 5-fluorouracil (5-FU) and tetrahydrogeraniol (THG) were prepared and the effects of THG on 5-FU permeation across the excised rat skin were studied by in vitro methods. Experiments on in vitro permeation of 5-FU across the skin with vertical diffusion cells showed that addition of THG to the gels markedly enhanced the 5-FU permeability. Increasing the THG concentration in the gels to 8% proportionally increased the permeability of 5-FU. More than 12 h was required to reach a steady-state level of 5-FU after administration of 5-FU-THG gel topically. The permeability parameters such as flux, permeability coefficient and enhancement ratio were determined. The results indicated a maximum flux of 252.91+/-9.61 microgram/cm2 per h, and the enhancement ratio of 31.22+/-1.18 when the THG concentration was 8%. Synergistic effects of propylene glycol (PG) with THG were also investigated and a maximum flux of 256.81+/-9.15 microgram/cm2 per h, was obtained when the PG concentration was 5% and THG was 8%. The corresponding enhancement ratio was 31.71+/-1.13. These results suggest not only that THG would be very useful for increasing the skin permeability of 5-FU, but also that THG being a natural product might be useful for developing transdermal therapeutic systems for the delivery of practically unabsorbable drugs.

Acrylic Resins↗

PubMed1998

pH of preparations affecting the on-off drug penetration behavior through the thermo-responsive liquid crystal-embedded membrane.

A liquid crystal (cholesteryl oleyl carbonate, COC)-embedded membrane with a controlled rate and higher reversibly thermo-responsive function was successfully fabricated by the vacuum filtration method. The aim of this study was to investigate the effect of the pH of aqueous solutions and gel preparations on the penetration of salbutamol sulfate through this thermo-responsive COC-embedded membrane. The results indicate that the on-off switching penetration behavior of salbutamol sulfate through the COC-embedded membrane in response to a repeatedly exchanging temperature cycle (10 <=> 25 degreesC) is not influenced by the pH of the medium. However, the pH-dependent ionization of salbutamol and the viscosity of the gel base, as well as the interaction between salbutamol and carbopol, might change the amount and the rate of salbutamol sulfate that penetrates across this COC-embedded membrane.

Acrylic Resins↗