Effects of Microwave on Drug Release Property of Poly(Methyl Vinyl Ether-co-Maleic Acid) Matrix

Development of Poly (Methyl vinyl ether-alt-maleic acid) Microneedles for Transdermal Delivery of Atorvastatin Calcium

AIMS

Biodegradable polymeric microneedles containing atorvastatin calcium were developed in order to improve the percutaneous absorption of the drug, useful for the treatment of hypercholesterolemia.

BACKGROUND

The use of physical enhancers like microneedles have shown good results to increase the delivery of drugs through the skin, the use of microneedles has very important advantages for transdermal drug delivery, for example, they are painless, easy to use and safe, they increase time interval of drug activity, dose, and reductions in adverse reactions, they also offer, the facility to remove the system instantly of the skin.

OBJECTIVE

Develop polymer microneedles loaded with a calcium atorvastatin and evaluate them by Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), bioadhesion, postwetting- bioadhesion, breaking strength, drug release test and in vitro percutaneous absorption studies to demonstrate the use of microneedles atorvastatin is able to cross the skin.

METHODS

The microneedles were made with poly (methyl vinyl ether-alt-maleic acid) as biodegradable polymer using the technique of casting in solution in a mold. After solidification these microneedles were characterized by Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), bioadhesion, post-wetting-bioadhesion, breaking strength, drug release test and in vitro percutaneous absorption studies.

RESULTS

In general, the performances were satisfactory for optimal formulation in terms of DSC with no interactions between drug and excipients, SEM shows microneedles with a conical shape, bioadhesion of 1570 g.f, post wetting-bioadhesion of 1503.4 g.f, breaking strength of 1566.7g.f that is sufficient to disrupt Stratum corneum, good drug release and a flux of 33.4 μg/cm2*h with a tLag of 15.14 h for the in vitro percutaneous absorption.

CONCLUSION

The results indicate that it is possible to generate microneedles to increase the percutaneous absorption of calcium atorvastatin transdermally, with the potential to be used as an alternative to the oral route for the treatment of dyslipidemias.

Synthetic hydrogels formed by thiol-ene crosslinking of vinyl sulfone-functional poly(methyl vinyl ether-alt-maleic acid) with α,ω-dithio-polyethyleneglycol

Polymer hydrogels formed by rapid thiol-ene coupling of macromolecular gel formers can offer access to versatile new matrices. This paper describes the efficient synthesis of cysteamine vinyl sulfone (CVS) trifluoroacetate, and its incorporation into poly(methyl vinyl ether-alt-maleic anhydride) (PMMAn) to form a series of CVS-functionalized poly(methyl vinyl ether-alt-maleic acid) polymers (PMM-CVS_x) containing 10 to 30 mol% pendant vinyl sulfone groups. Aqueous mixtures of these PMM-CVS and a dithiol crosslinker, α,ω-dithio-polyethyleneglycol (HS-PEG-SH, M_n = 1 kDa), gelled through crosslinking by Michael addition within seconds to minutes, depending on pH, degree of functionalization, and polymer loading. Gelation efficiency, Young's modulus, equilibrium swelling and hydrolytic stability are described, and step-wise hydrogel post-functionalization with a small molecule thiol, cysteamine, was demonstrated. Cytocompatibility of these crosslinked hydrogels towards entrapped 3T3 fibroblasts was confirmed using a live/dead fluorescence assay.

Cross-Linked Hydrogels Formed through Diels-Alder Coupling of Furan- and Maleimide-Modified Poly(methyl vinyl ether-alt-maleic acid)

The Diels-Alder [4 + 2] cycloaddition between furan- and maleimide-functional polyanions was used to form cross-linked synthetic polymer hydrogels. Poly(methyl vinyl ether-alt-maleic anhydride) was reacted with furfurylamine or N-(2-aminoethyl)maleimide in acetonitrile to form pairs of furan- and maleimide-functionalized poly(methyl vinyl ether-alt-maleic acid)s. Mixtures of these mutually reactive polyanions in water gelled within 15 min to 18 h, depending on degree of functionalization and polymer concentrations. Solution and magic-angle spinning (1)H NMR were used to confirm the formation of the Diels-Alder adduct, to analyze competing hydrolytic side reactions, and demonstrate postgelation functionalization. The effect of the degree of furan and maleimide functionalization, polymer concentration, pH, and calcium ion concentration, on gelation time, gel mechanical properties, and equilibrium swelling, are described. Release of dextran as a model drug was studied using fluorescence spectroscopy, as a function of gel composition and calcium treatment.

Effects of microwave on drug-release responses of spray-dried alginate microspheres

CONTEXT

Microspheres prepared from rigid guluronic acid- (MG) and flexible mannuronic acid-rich (MC) alginate will undergo different drug release changes with respect to the influence of microwave on the matrix. An in-depth understanding of their differences in drug release changes is attainable through investigating cross-linking agent-free alginate microspheres prepared by spray-drying technique.

OBJECTIVE

The behavior of MG and MC alginate in controlling drug release responses of spray-dried microspheres against microwave was investigated. Sodium diclofenac was used as a model water-soluble drug. The formed microspheres were subjected to drug release, drug content, size, shape, surface morphology, Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffractometry analysis.

RESULTS

MC microspheres required a shorter period of microwave irradiation to reduce drug release extent than MG microspheres. In response to microwave, the drug release profiles of 1:1 MG-MC microspheres resembled MC microspheres.

DISCUSSION

The state of polymer-polymer and drug-polymer interaction via O-H and/or N-H moiety of microspheres was affected by alginate chain flexibility under the influence of microwave. It then governed the drug release responses of microspheres.

CONCLUSION

The drug release property of alginate microspheres can be modified by microwave irradiation, and its changes are a function of alginate conformation.

Design of in situ dispersible and calcium cross-linked alginate pellets as intestinal-specific drug carrier by melt pelletization technique

Conventional alginate pellets underwent rapid drug dissolution and loss of multiparticulate characteristics such as aggregation in acidic medium, thereby promoting oral dose dumping. This study aimed to design sustained-release dispersible alginate pellets through rapid in situ matrix dispersion and cross-linking by calcium salts during dissolution. Pellets made of alginate and calcium salts were prepared using a solvent-free melt pelletization technique that prevented reaction between processing materials during agglomeration and allowed such a reaction to occur only in dissolution phase. Drug release was remarkably retarded in acidic medium when pellets were formulated with water-soluble calcium acetate instead of acid-soluble calcium carbonate. Different from calcium salt-free and calcium carbonate-loaded matrices that aggregated or underwent gradual erosion, rapid in situ solvation of calcium acetate in pellets during dissolution resulted in burst of gas bubbles, fast pellet breakup, and dispersion. The dispersed fragments, though exhibiting a larger specific surface area for drug dissolution than intact matrix, were rapidly cross-linked by Ca(2+) from calcium acetate and had drug release retarded till a change in medium pH from 1.2 to 6.8. Being dispersible and pH-dependent in drug dissolution, these pellets are useful as multiparticulate intestinal-specific drug carrier without exhibiting dose dumping tendency of a "single-unit-like" system via pellet aggregation.