Preparation and tabletting of dipyridamole alginate-Eudragit microspheres

Development of Novel EE/Alginate Polyelectrolyte Complex Nanoparticles for Lysozyme Delivery: Physicochemical Properties and In Vitro Safety

The number of biologic drugs has increased in the pharmaceutical industry due to their high therapeutic efficacy and selectivity. As such, safe and biocompatible delivery systems to improve their stability and efficacy are needed. Here, we developed novel cationic polymethacrylate-alginate (EE-alginate) pNPs for the biologic drug model lysozyme (Lys). The impact of variables such as total charge and charge ratios over nanoparticle physicochemical properties as well as their influence over in vitro safety (viability/proliferation and cell morphology) on HeLa cells was investigated. Our results showed that electrostatic interactions between the EE-alginate and lysozyme led to the formation of EE/alginate Lys pNPs with reproducible size, high stability due to their controllable zeta potential, a high association efficiency, and an in vitro sustained Lys release. Selected formulations remained stable for up to one month and Fourier transform-Infrared (FT-IR) showed that the functional groups of different polymers remain identifiable in combined systems, suggesting that Lys secondary structure is retained after pNP synthesis. EE-alginate Lys pNPs at low concentrations are biocompatible, while at high concentrations, they show cytotoxic for HeLa cells, and this effect was found to be dose-dependent. This study highlights the potential of the EE-alginate, a novel polyelectrolyte complex nanoparticle, as an effective and viable nanocarrier for future drug delivery applications.

Multi-unit floating alginate system: effect of additives on ciprofloxacin release

In an attempt to fabricate floating beads of ciprofloxacin, drugloaded alginate beads were prepared by simultaneous external and internal gelation. The effect of blending of alginate with gellan, hydroxypropyl methylcellulose, starch, and chitosan on the bead properties were evaluated. Beads were spherical with incorporation efficiency in the range of 52.81 +/- 2.64 to 78.95 +/- 1.92%. Beads exhibited buoyancy over a period of 7-24 hr based on the formulation variables. In vitro release of ciprofloxacin from the alginate beads in simulated gastric fluid (SGF) (0.1 N HCl, pH 1.2), was influenced significantly (p < 0.001) by the properties and concentration of additives. Among the polymers incorporated into alginate beads. Hydroxy propyl methylcellulose (HPMC) provided an extended release over 7 hr. The drug release predominately followed Higuchi's square root model.

Review and current status of emulsion/dispersion technology using an internal gelation process for the design of alginate particles

Emulsification/internal gelation has been suggested as an alternative to extrusion/external gelation in the encapsulation of several compounds including sensitive biologicals such as protein drugs. Protein-loaded microparticles offer an inert environment within the matrix and encapsulation is conducted at room temperature in a media free of organic solvents. Recently, the concept of internal gelation has been applied to formulating nanoparticles as drug delivery systems. Emulsification/internal gelation technologies available for microparticles preparation, particularly that involving alginate polymer, are described as well as recent advances towards applications in nanotechnology. Those methods show great promise as a tool for the development of encapsulation processes, especially for the new field of nanotechnology using natural polymers.

Polyionic hydrocolloids for the intestinal delivery of protein drugs: alginate and chitosan--a review

The protein pharmaceutical market is rapidly growing, since it is gaining support from the recombinant DNA technology. To deliver these drugs via the oral route, the most preferred route, is the toughest challenge. In the design of oral delivery of peptide or protein drugs, pH sensitive hydrogels like alginate and chitosan have attracted increasing attention, since most of the synthetic polymers are immunogenic and the incorporation of proteins in to these polymers require harsh environment which may denature and inactivate the desired protein. Alginate is a water-soluble linear polysaccharide composed of alternating blocks of 1-4 linked alpha-L-guluronic and beta-D-mannuronic acid residues where as chitosan is a co polymer of D-glucosamine and N-acetyl glucosamine. The incorporation of protein into these two matrices can be done under relatively mild environment and hence the chances of protein denaturation are minimal. The limitations of these polymers, like drug leaching during preparation can be overcome by different techniques which increase their encapsulation efficiency. Alginate, being an anionic polymer with carboxyl end groups, is a good mucoadhesive agent. The pore size of alginate gel microbeads has been shown to be between 5 and 200 nm and coated beads and microspheres are found to be better oral delivery vehicles. Cross-linked alginate has more capacity to retain the entrapped drugs and mixing of alginate with other polymers such as neutral gums, pectin, chitosan, and eudragit have been found to solve the problem of drug leaching. Chitosan has only limited ability for controlling the release of encapsulated compound due to its hydrophilic nature and easy solubility in acidic medium. By simple covalent modifications of the polymer, its physicochemical properties can be changed and can be made suitable for the peroral drug delivery purpose. Ionic interactions between positively charged amino groups in chitosan and the negatively charged mucus gel layer make it mucoadhesive. The favourable properties like biocompatibility, biodegradability, pH sensitiveness, mucoadhesiveness, etc. has enabled these polymers to become the choice of the pharmacologists as oral delivery matrices for proteins.

Cross-linked alginate–gelatine beads: a new matrix for controlled release of pindolol

This work is focused on the development of a new particulate drug delivery system using a sodium alginate matrix containing pindolol as a model drug molecule for intestinal drug prolonged release. Calcium alginate beads are known to be unable to control the release of most insoluble drugs. Pindolol-loaded alginate-gelatine beads have been developed using a solvent-free technique that involves a cross-linking reaction. Modifications in matrix structure and physicochemical behaviour caused by the cross-linking reaction were assessed during particle formation and drug release. Several parameters, such as matrix gelling rate, encapsulation efficiency, drug release profile and matrix erosion rate, were investigated. Physicochemical characterisation indicates the formation of a new alginate-gelatine matrix and shows that pindolol does not interfere with the matrix formation process. Matrix swelling of calcium alginate beads induced by phosphate buffer ends up in erosion and destruction. However, for cross-linked beads swelling does not lead to complete erosion, which may be the main cause of pindolol retention within the matrix. The modifications introduced in the initial calcium alginate formulation by means of an appropriate method such as the use of a cross-linking agent successfully changed the matrix performance, allowing the controlled release of pindolol.

Development of hollow microspheres as floating controlled-release systems for cardiovascular drugs: preparation and release characteristics

Hollow microspheres of cellulose acetate loaded with four cardiovascular drugs (nifedipine [NFD], nicardapine hydrochloride [NCD], verapamil hydrochloride [VRP], and dipyridamole [DIP]) were prepared by a novel solvent diffusion-evaporation method. The oil-in-water emulsion prepared in an aqueous solution of 0.05% poly(vinyl alcohol) medium with ethyl acetate, a water-soluble and less toxic solvent, was used as the dispersing solvent. The yield of the microspheres was up to 80%. The microspheres had smooth surfaces, with free-flowing and good-packing properties. Scanning electron microscopy (SEM) confirmed their hollow structures, with sizes in the range 489-350 microm. The microspheres tended to float over the gastric media for more than 12 h. The drug loaded in hollow microspheres was in an amorphous state, as confirmed by differential scanning microscopy (DSC). The release of the drugs was controlled for more than 8 h. The release kinetics followed different transport mechanisms depending on the nature of the drug molecules.

Effect of tabletting compaction pressure on alginate microspheres

Alginate and alginate-hydroxypropylmethylcellulose (HPMC) microspheres were prepared by the emulsification method. The compaction of microspheres for producing tablet dosage forms raises concerns about possible damage to microsphere walls with subsequent unpredictable dissolution rates. The effect of different compaction pressures on the integrity of the microspheres was investigated. The addition of a diluent, microcrystalline cellulose (MCC), was required to make compacts containing alginate and alginate-HPMC microspheres. Compacts containing alginate-HPMC (7:3) microspheres had the highest crushing strength followed by compacts containing alginate-HPMC (9:1) microspheres and alginate microspheres. However, compact crushing strength did not vary significantly with increased compaction pressures over the range of compaction pressures investigated. Differences in the drug release profiles of the original non-compacted and compacted alginate and alginate-HPMC microspheres were slight and not marked. Although dentation and distortion of the microspheres were observed with increasing compaction pressures, the microspheres generally remained intact, with minimal rupture/fracture.

Sustained release properties of alginate microspheres and tabletted microspheres of diclofenac sodium

This study focused on the properties of diclofenac sodium (DNa) alginate (alg) microspheres and tabletted DNa alg microspheres using different polymers as additives. DNa alginate microspheres were prepared by the emulsification method and different polymers such as Eudragit (Eud) NE 30 D, Eudragit (Eud) RS 30 D and Aquacoat, which were incorporated into alg gel to control the release rate of drug. The release properties of DNa alg microspheres (1:1) were affected by the size, drug load of microspheres and also by the incorporated polymers, pH and ionic strength of dissolution medium. Tabletting of alg microspheres using carrageenan (carr), alg, pectin, NaCMC, tragacanth (trgh) and HPMC as additives in a (50:50) ratio produced tablets with good physical properties and also better controlled release of DNa. Dissolution studies were carried out in pH 7.2 phosphate buffer and phosphate buffers whose pH values were gradually changed from pH 3 to 7.4. The rank order of DNa release from tablets was carr < alg < pectin < NaCMC < trgh < HPMC which relates to the viscosity and swelling properties of polymers. The drug release was very slow from trgh and HPMC based tablets, but addition of carr or alg in different ratios could adjust the release rate of drug.

Polymers for sustained release formulations of dipyridamole-alginate microspheres and tabletted microspheres

The preparation of dipyridamole (DIP) alginate (alg) microspheres by different methods or the incorporation of tragacanth (trgh), pectin or Eudragit L-100 55 (Eud) in alg microsphere formulations did not provide a prolonged release of DIP at pH 1.2. Tabletted microsphere formulations containing alg, trgh, pectin, sodium carboxymethyl cellulose (CMC), sodium starch glycolate (SSG), carrageenan (carrg) or Eud as diluents in different ratios, produced tablets with good physical properties which did prolong DIP release. The type, viscosity and the ratio of the diluent polymer, microsphere size and the compression pressure were found to be important factors to produce tablets with desired properties. No advantage of the tablets containing alg microspheres and granulated diluents was observed over the tablets containing powdered diluents.