PEGylated rosin derivatives: novel microencapsulating materials for sustained drug delivery

Advances in Rosin-Based Chemicals: The Latest Recipes, Applications and Future Trends

A comprehensive review of the publications about rosin-based chemicals has been compiled. Rosin, or colophony, is a natural, abundant, cheap and non-toxic raw material which can be easily modified to obtain numerous useful products, which makes it an excellent subject of innovative research, attracting growing interest in recent years. The last extensive review in this research area was published in 2008, so the current article contains the most promising, repeatable achievements in synthesis of rosin-derived chemicals, published in scientific literature from 2008 to 2018. The first part of the review includes low/medium molecule weight compounds: Especially intermediates, resins, monomers, curing agents, surfactants, medications and biocides. The second part is about macromolecules: mainly elastomers, polymers for biomedical applications, coatings, adhesives, surfactants, sorbents, organosilicons and polysaccharides. In conclusion, a critical evaluation of the publications in terms of data completeness has been carried out with an indication of the most promising directions of rosin-based chemicals development.

Design and evaluation of dental films of PEGylated rosin derivatives containing sparfloxacin for periodontitis

OBJECTIVE

In this study, PEGylated rosin derivatives (PRDs) namely D1 and D2 were synthesized and evaluated for their application to produce sustained-release antibacterial films containing sparfloxacin for periodontitis.

SIGNIFICANCE

PRDs are biodegradable and biocompatible, and therefore sustained-release dental implant of PRD-sparfloxacin can provide an effectual treatment for periodontitis.

METHODS

Films were produced by solvent casting technique and characterized for morphology, swelling-index, in vitro degradation and drug release kinetics. The impact of type of PRD, concentration of PRDs, and addition of plasticizer (dibutyl phthalate) on various film properties was evaluated. The films were also subjected to stability study at 30 °C and 40 °C for 90 days.

RESULTS

Both D1 and D2 produced smooth and non-porous films with sparfloxacin. The D1 films, due to lower amount of polyethylene glycol 400 in D1, exhibited lower swelling-index, slower degradation, and slower drug release compared to D2 films. An increase in PRDs concentration decreased swelling-index, prolonged degradation time, and decreased drug release rate of films; addition of plasticizer showed the similar effect. At pH 7.6, D1 and D2 films showed complete degradation at the end of 58 and 51 days, respectively. At the end of 21 days, D1 and D2 films released 41.85% and 61.53% sparfloxacin, respectively. The drug release from D1 films followed Higuchi square-root kinetics, while D2 films released drug by the zero order kinetics. The stability conditions did not significantly alter PRDs-film properties.

CONCLUSION

Results revealed that PRDs can be used successfully to produce sustained-release antibacterial films containing sparfloxacin for the treatment of periodontitis.

Surface Properties and Structural Transformation Behaviors of mPEG-Maleic Rosin Copolymer in Water

mPEG (monomethoxy poly(ethylene glycol))-maleic rosin copolymer was successfully prepared. The surface properties of the copolymer were investigated by surface tension and resonance scattering techniques. The critical micelle concentration (CMC) was obtained. The adsorption behaviors and the conformational changes of the surfactant molecules at the air-water interface were described. The adsorption amount of state 1 presented a sinusoid shape and that of state 2 presented a sigmoid with the growth of П. The free energy of adsorption is more negative than that of micellization, thus, the surfactant molecules adsorb on the surface firstly, and then form micelles after saturation adsorption. Accordingly, structural transformation and aggregation behaviors of various concentration mPEG-maleic rosin copolymers with changing temperature were explored in water. The mPEG-maleic rosin chains experienced transformation from unimers to aggregates, to contracted aggregates, to cohesive aggregates with increasing temperature when the concentration is lower than CMC. This process is almost reversible with decreasing temperature. Transformation from micelle to aggregate with increasing temperature happened when the concentration is higher than CMC. The phenomena were assessed by DLS (dynamic light scattering) and SEM (scanning electron microscopy) techniques.

Evaluation of gum mastic (Pistacia lentiscus) as a microencapsulating and matrix forming material for sustained drug release

In this study, a natural gum mastic was evaluated as a microencapsulating and matrix-forming material for sustained drug release. Mastic was characterized for its physicochemical properties. Microparticles were prepared by oil-in-oil solvent evaporation method. Matrix tablets were prepared by wet and melt granulation techniques. Diclofenac sodium (DFS) and diltiazem hydrochloride (DLTZ) were used as model drugs. Mastic produced discrete and spherical microspheres with DLTZ and microcapsules with DFS. Particle size and drug loading of microparticles was in the range of 22–62 µm and 50–87%, respectively. Increase in mastic: drug ratio increased microparticle size, improved drug loading and decreased the drug release rate. Microparticles with gum: drug ratio of 2:1 could sustain DLTZ release up to 12 h and released 57% DFS in 12 h. Mastic produced tablets with acceptable pharmacotechnical properties. A 30% w/w of mastic in tablet could sustain DLTZ release for 5 h from wet granulation, and DFS release for 8 h and 11 h from wet and melt granulation, respectively. Results revealed that a natural gum mastic can be used successfully to formulate matrix tablets and microparticles for sustained drug release.

Study of biodegradation and biocompatibility of PEGylated rosin derivatives

PEGylated rosin derivatives are improved in series ester-adduct derivatives of rosin. The aim of this study was to assess biodegradation and biocompatibility of PEGylated rosin derivatives. Study employed two different PEGylated rosin derivatives, namely, D1 and D2, with constant weight of rosin and increasing amounts of polyethylene glycol 400. PEGylated rosin derivatives were synthesized and tailored into spherical beads and disks with smooth surface for use. In vitro degradation was studied at pH 4.0, 7.4, and 10 for 60 days. In vivo study was performed in Wistar rats using poly(d,l-lactide- co-glycolide) (50:50) as a control. Post 3, 7, 14, and 21 days of implantation, PEGylated rosin derivatives disks were retrieved and evaluated for weight loss, molecular weight decline, morphology, and tissue response. D1 and D2 beads showed 21.68% and 32.37% weight loss, respectively, at pH 7.4 post 60 days. Degradation was increased substantially with increase in pH of medium. Degradation of disks was markedly slower than that of beads. In vivo degradation of PEGylated rosin derivative disks was faster than in vitro. Post 60 days of implantation, weight loss of D1 and D2 disk was 7.57% and 11.84%, whereas molecular weight was declined by about 19% and 26%, respectively. Owing to higher amounts of polyethylene glycol 400, in vitro and in vivo degradation of D2 was faster than D1. Poly(d,l-lactide- co-glycolide) as well as PEGylated rosin derivative implants evoked mild inflammatory responses characterized by few macrophages and absence of exudation at tissue–disk interface. The cellular density in tissue surrounding PEGylated rosin derivative disks increased initially with time up to 7 days and decreased eventually at the end of 21 days. The trend was similar for poly(d,l-lactide- co-glycolide) implants. Increase in polyethylene glycol 400 improved biodegradation and biocompatibility of PEGylated rosin derivatives. Results revealed that PEGylated rosin derivatives degrade slowly in vivo over a period of time, possess fair biocompatibility, and thus are promising biomaterial for drug delivery applications.

Rosin: Recent advances and potential applications in novel drug delivery system

Gum exudates are among the oldest natural polymer. Natural gums have remained one of the major areas of interest for the researchers for their applicability in the drug delivery system because of their wide availability, inexpensiveness and availability in a variety of structures with varied properties. They can be easily modified chemically, biochemically and are highly stable, safe, non-toxic, gel forming and in addition are biodegradable. Rosin is one of the natural gums obtained as resinous constituent of the oleoresin exuded by various species of pine, mostly conifers. Rosin consists primarily of abietic- and pimaric-type resin acids (or rosin acids) with characteristic hydrophobic hydrophenanthrene rings which impart them excellent film-forming properties. Rosin and its derivatives are biopolymers that are increasingly used for their pharmaceutical applications. In the pharmaceutical field, it has been investigated for film-forming and coating properties, microencapsulation and as a matrix material in the tablets for sustained and controlled drug release. This article reviews the literature on rosin and its derivative and describes the varied applications of the rosin and their future exploitation in novel drug delivery systems.

Preparation of pH-sensitive beads for NSAID using three-component gel systems

The aim of this study is to prepare novel pH-sensitive beads to obtain a gastric mucosa protective formulation and to ensure drug delivery into the intestine. Diclofenac sodium was used as a model drug. Bead formation was achieved by ionotropic gelation method using three-component gel system containing sodium alginate (Na-Alg), hydroxyethylcellulose (HEC) and hydroxypropylmethylcellulose (HPMC). Factors influencing the characteristics of beads (exposure time, cross-linking agent concentration, polymer ratio) were investigated by swelling and erosion tests based on gravimetric method. Drug release was tested in distilled water and/or artificial digestive fluids and evaluated with Korsmeyer-Peppas equation and Baker-Lonsdale model. The encapsulation behaviour was qualitatively indicated by differential scanning calorimetry (DSC) method. In vivo experiments were conducted to test ulcerogenicity and intestinal absorption in rats. HPMC increased the encapsulation efficiency (EE) and HEC improved the drug release in the intestinal fluids. The equilibrium water uptake (EWU) was correlated with exposure time, calcium chloride concentration and HEC amounts. Bead erosion increased proportionately to exposure time, while it reduced when calcium chloride concentrations were increased. Higher amounts of HEC increased, while higher pH values reduced the encapsulation efficacy. The in vivo experiments demonstrated that the studied encapsulation technology markedly reduced the ulcerogenic effect of diclofenac.