Concept: Carnauba wax
Objective: Solventless dry powder coating methods have many advantages compared to solvent-based methods: they are more economical, simpler, safer, more environmentally friendly and easier to scale up. The purpose of this study was to investigate a highly effective dry powder coating method using the mechanofusion system, a mechanochemical treatment equipped with high compressive and shearing force.Materials and methods: Acetaminophen (AAP) and carnauba wax (CW) were selected as core particles of the model drug and coating material, respectively. Mixtures of AAP and CW with and without talc were processed using the mechanofusion system.Results: Sustained AAP release was observed by selecting appropriate processing conditions for the rotation speed and the slit size. The dissolution rate of AAP processed with CW substantially decreased with an increase in talc content up to 40% of the amount of CW loaded. Increasing the coating amount by two-step addition of CW led to more effective coating and extended drug release. Scanning electron micrographs indicated that CW adhered and showed satisfactory coverage of the surface of AAP particles.Conclusion: Effective CW coating onto the AAP surface was successfully achieved by strictly controlling the processing conditions and the composition of core particles, coating material and glidant. Our mechanochemical dry powder coating method using the mechanofusion system is a simple and promising means of solventless pharmaceutical coating.
Physico-chemical properties and efficacy of silk fibroin fabric coated with different waxes as wound dressing
- International journal of biological macromolecules
- Published almost 7 years ago
Silk fibroin (SF) has been widely used as a wound dressing material due to its suitable physical and biological characteristics. In this study, a non-adhesive wound dressing which applies to cover the wound surface as an absorbent pad that would absorb wound fluid while accelerate wound healing was developed. The modification of SF fabrics by wax coating was purposed to prepare the non-adhesive wound dressing that is required in order to minimize pain and risk of repeated injury. SF woven fabrics were coated with different types of waxes including shellac wax, beeswax, or carnauba wax. Physical and mechanical properties of the wax-coated SF fabrics were characterized. It was clearly observed that all waxes could be successfully coated on the SF fabrics, possibly due to the hydrophobic interactions between hydrophobic domains of SF and waxes. The wax coating improved tensile modulus and percentage of elongation of the SF fabrics due to the denser structure and the thicker fibers coated. The in vitro degradation study demonstrated that all wax-coated SF fabrics remained up to 90% of their original weights after 7 weeks of incubation in lysozyme solution under physiological conditions. The wax coating did not affect the degradation behavior of the SF fabrics. A peel test of the wax-coated SF fabrics was carried out in the partial- and full-thickness wounds of porcine skin in comparison to that of the commercial wound dressing. Any wax-coated SF fabrics were less adhesive than the control, as confirmed by less number of cells attached and less adhesive force. This might be that the wax-coated SF fabrics showed the hydrophobic property, allowing the loosely adherence to the hydrophilic wound surface. In addition, the in vivo biocompatibility test of the wax-coated SF fabrics was performed in Sprague-Dawley rats with subcutaneous model. The irritation scores indicated that the carnauba wax-coated SF fabric was not irritant while the shellac wax or beeswax-coated SF fabrics were slightly irritant, comparing with the commercial wound dressing. Therefore, SF fabrics coated with waxes, particularly carnauba wax, would be promising choices of non-adhesive wound dressing.
Carnauba wax is extracted from the leaves of the Copernicia prunífera and contains approximately 80% of esters in its composition. The purpose of the present study was evaluate the hypolipidemic effect of p-methoxycinnamic diesters (PCO-C) extracted from Copernicia prunífera in a model of acute and chronic dyslipidemia in mice. The levels of total cholesterol and triglycerides were significantly reduced plasma levels in PCO-C at the dose of 100mg/kg in a model of acute and chronic dyslipidemia. Histological studies showed that PCO-C has no hepatotoxic effect and reduces hepatic steatosis in animals that consumed hyperlipidemic ration. Thus, it was concluded that PCO-C isolated from Copernicia Prunifera was effective in reducing total cholesterol and triglyceride levels in both dyslipidemia induction models. The finding indicates that PCO-C might be beneficial in treatment of hyperlipidemia and atherosclerosis.
‘Carnauba’ wax is a natural product obtained from the processing of the powder exuded from Copernicia prunifera (Miller) H. E. Moore (Arecaceae). This material is widely used in the Brazilian folk medicine, including the treatment of rheumatism and syphilis.
The bis (1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl)-decandioate (IAC), is an innovative non- radical scavenger used with success in numerous disease models such as inflammation, neurological disorders, hepatitis and diabetes. The pharmacological treatments have been performed by the intraperitoneal route of administration, representing to date, the main limit for the drug use. The aim of this study was to develop a delivery system that allows the oral administration of IAC while maintaining its therapeutic efficacy. Solid Lipid Microparticles (SLMs) containing a theoretical 18% (w/w) of IAC have been produced by the spray congealing technology; three formulations have been tested (A, B and C) using different low melting point carriers (stearic acid, Compritol(®) HD5ATO and carnauba wax) alone or in combination. All IAC loaded SLMs exhibited a spherical shape, encapsulation efficiency higher than 94% and particle size suitable for the oral route. Administered per os at different dosages in an inflammation rat model, all SLMs demonstrated their efficacy in reducing oedema and alleviating pain, compared to the gold standards Indomethacin and Paracetamol. These results suggested that the SLMs are an efficacious delivery system for the oral administration of IAC, potentially useful for the treatment of others diseases related to an over production of free radicals.
The aim of this study was to use a detailed rheological characterization to gain new insights into the gelation behavior of natural waxes. To make a comprehensive case, six natural waxes (differing in the relative proportion of chemical components: hydrocarbons, fatty alcohols, fatty acids and wax esters) were selected as organogelators to gel high oleic sunflower oil. Flow and dynamic rheological properties of organogels prepared at critical gelling concentrations (Cg) of waxes were studied and compared using drag (stress ramp and steady flow) and oscillatory shear (stress and frequency sweeps) tests. Although, none of the organogels satisfied the rheological definition of a ‘strong gel’ (G"/G' (ω) ≤ 0.1), on comparing the samples, the strongest gel (highest critical stress and dynamic, apparent and static yield stresses) was obtained not with wax containing highest proportion of wax esters alone (sunflower wax, SFW) but with wax containing wax esters along with a higher proportion of fatty alcohols (carnauba wax, CRW) although, at a comparatively higher Cg (4 %wt for latter compared to 0.5 %wt for former). As expected, gel formation by waxes containing high proportion of lower melting fatty acids (berry, BW and fruit wax, FW) required a comparatively higher Cg (6 and 7 %wt respectively) and in addition, these gels showed lowest values for plateau elastic modulus (G'LVR) and a prominent crossover point at higher frequency. The gelation temperatures (TG' = G") for all the studied gels were lower than the room temperature except for SFW and CRW. The yielding type behavior of gels was evident with most gels showing strong shear sensitivity and a weak thixotropic recovery. The rheological behavior was combined with the results of thermal analysis and microstructure studies (optical, polarized and cryo-scanning electron microscopy) to explain the gelation properties of these waxes.
The effect of three different coatings; resin wax (Britex Ti), carnauba wax (Xedasol M14), and chitosan (1 and 2 % w/v) on postharvest quality of pomegranate fruits were investigated. Fruits quality characteristics and bioactive compounds were evaluated during 40, 80 and 120 days storage at 4.5 °C and 3 additional days at 20 °C. The results showed that uncoated fruits showed higher respiration rate, weight loss, L* and b* values of arils, total soluble solids (TSS)/titratable acidity (TA), and pH than coated fruits during storage. Coating treatments could delay declining TSS and TA percent, a* value of arils, as well as bioactive compounds such as total phenolics, flavonoids and anthocyanins content and antioxidant activity. The coated fruits with commercial resin and carnauba waxes showed significantly lower respiration rate and weight loss than other treatments, however carnauba wax could maintain considerably higher fruits quality and bioactive compounds than other coating treatments. The results suggested that postharvest application of carnauba wax have a potential to extend storage life of pomegranate fruits by reducing respiration rate, water loss and maintaining fruit quality.
A novel solvent-less dry-polymer coating process employing high-intensity vibrations avoiding the use of liquid plasticizers, solvents, binders, and heat treatments is utilized for the purpose of controlled release. The main hypothesis is that such process having highly controllable processing intensity and time may be effective for coating particularly fine particles, 100 μm and smaller via exploiting particle interactions between polymers and substrates in the dry state, while avoiding breakage yet achieving conformal coating. The method utilizes vibratory mixing to first layer micronized polymer onto active pharmaceutical ingredient (API) particles by virtue of van der Waals forces and to subsequently mechanically deform the polymer into a continuous film. As a practical example, ascorbic acid and ibuprofen microparticles, 50-500 μm, are coated with the polymers polyethylene wax or carnauba wax, a generally recognized as safe material, resulting in controlled release on the order of seconds to hours. As a novelty, models are utilized to describe the coating layer thickness and the controlled-release behavior of the API, which occurs because of a diffusion-based mechanism. Such modeling would allow the design and control of the coating process with application for the controlled release of microparticles, particularly those less than 100 μm, which are difficult to coat by conventional solvent coating methods. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci.
In personalized medicine and patient-centered medical treatment individual dosing of medicines is crucial. The Solid Dosage Pen (SDP) allows for an individual dosing of solid drug carriers by cutting them into tablet-like slices. The aim of the present study was the development of sustained release and dual release formulations with carbamazepine (CBZ) via hot-melt co-extrusion for the use in the SDP. The selection of appropriate coat- and core-formulations was performed by adapting the mechanical properties (like tensile strength and E-modulus) for example. By using different excipients (polyethyleneglycols, poloxamers, white wax, stearic acid, and carnauba wax) and drug loadings (30 - 50%) tailored dissolution kinetics were achieved showing cube root or zero order release mechanisms. Besides a biphasic drug release, the dose-dependent dissolution characteristics of sustained release formulations were minimized by a co-extruded wax-coated formulation. The dissolution profiles of the co-extrudates were confirmed during short term stability study (six months at 21.0±0.2°C, 45%r.H). Due to a good layer adhesion of core and coat and adequate mechanical properties (maximum cutting force of 35.8 ± 2.0 N and 26.4 ± 2.8 N and E-modulus of 118.1 ± 8.4 and 33.9 ± 4.5 MPa for the dual drug release and the wax-coated co-extrudates, respectively) cutting off doses via the SDP was precise. While differences of the process parameters (like the barrel temperature) between the core- and the coat-layer resulted in unsatisfying content uniformities for the wax-coated co-extrudates, the content uniformity of the dual drug release co-extrudates was found to be in compliance with pharmacopoeial specification.
The D-optimal mixture experimental design was employed to optimize the melting point of natural lipstick based on pitaya (Hylocereus polyrhizus) seed oil. The influence of the main lipstick components-pitaya seed oil (10%-25% w/w), virgin coconut oil (25%-45% w/w), beeswax (5%-25% w/w), candelilla wax (1%-5% w/w) and carnauba wax (1%-5% w/w)-were investigated with respect to the melting point properties of the lipstick formulation. The D-optimal mixture experimental design was applied to optimize the properties of lipstick by focusing on the melting point with respect to the above influencing components. The D-optimal mixture design analysis showed that the variation in the response (melting point) could be depicted as a quadratic function of the main components of the lipstick. The best combination of each significant factor determined by the D-optimal mixture design was established to be pitaya seed oil (25% w/w), virgin coconut oil (37% w/w), beeswax (17% w/w), candelilla wax (2% w/w) and carnauba wax (2% w/w). With respect to these factors, the 46.0 °C melting point property was observed experimentally, similar to the theoretical prediction of 46.5 °C. Carnauba wax is the most influential factor on this response (melting point) with its function being with respect to heat endurance. The quadratic polynomial model sufficiently fit the experimental data.