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Gonadotropin-releasing hormone (GnRH) agonists are peptides consisting of nine or ten amino acid residues. GnRH agonists have been applied in the therapy of sexual hormone disorders like prostate cancer, endometriosis, uterine myoma, central precious puberty, and in-vitro fertility. Treatment is achieved by continuous hormone intake and long-term agonists administration, which is usually associated with poor patient compliance. Because GnRH agonists that are administered with the parenteral route are broken down by peptidase, their half-life is short. As a result, developing sustained release for the drug delivery system is significant. Even though some drugs have been successfully delivered with long-acting release microspheres and approved by the Food and Drug Administration (FDA), some challenges remain. This review highlighted current approaches to encapsulate GnRH agonists into delivery systems and strategies encountered during the loading process. Moreover, the following sections provide strategies to improve the release profile, and animal and human studies were summarised. [ABSTRACT FROM AUTHOR]

Background: Lavender oil consists of around 100 components and is susceptible to volatilisation and degradation reactions. Aim: Microencapsulate lavender oil by spray drying using a biocompatible polymeric blend of gum acacia and maltodextrin to protect the oil components. Effect of total polymer content, oil loading, gum acacia, and maltodextrin proportions on the size, yield, loading, and encapsulation efficiency of the microparticles was investigated. Methods: Morphology and oil localisation within microparticles were assessed by confocal laser scanning electron microscope. Structural preservation and compatibility were assessed using Fourier transform infra-red spectroscopy, differential scanning calorimetry, and gas chromatography–mass spectrometry. Results: Lavender microparticles of size 12.42 ± 1.79 µm prepared at 30 w/w% polymer concentration, 16.67 w/w% oil loading, and 25w/w% gum acacia showed maximum oil protection at high loading (12 mg w/w%), and encapsulation efficiency (77.89 w/w%). Conclusion: Lavender oil was successfully microencapsulated into stable microparticles by spray drying using gum acacia/maltodextrin polymeric blend. [ABSTRACT FROM AUTHOR]

The aim of this work was to study the use of different prebiotic biopolymers in lime essential oil microencapsulation. Whey protein isolate, inulin and oligofructose biopolymers were used. The addition of prebiotic biopolymers reduced emulsion viscosity, although it produced larger droplet sizes (0.31–0.32 µm). Moisture values (2.94–3.13 g/100 g dry solids) and water activity (0.152–0.185) were satisfactory, being within the appropriate range for powdered food quality. Total oil content, limonene retention values and antioxidant activity of the microparticles containing essential oil decreased in the presence of the carbohydrates. The addition of prebiotic biopolymers reduced the microparticle thermal stability. X-ray diffraction confirmed the amorphous characteristic of the microparticles and the interaction of the essential oil with the wall material. The presence of prebiotic biopolymers can be a good alternative for lime essential oil microparticles, mainly using fibre that has a functional food appeal and can improve consumer health. [ABSTRACT FROM PUBLISHER]

Encapsulation is an established technique to protect sensitive materials from environmental stress. In order to understand the physical protection mechanism against oxidation, knowledge about the powder microstructure is required. Time domain-nuclear magnetic resonance (TD-NMR) has the potential to determine the surface oil (SO) and droplet size distribution by relaxation and restricted self-diffusion, respectively. The amount of SO, the retention and encapsulation efficiency are determined based on a lipid balance. The oil load of the initial powder and after SO removal is measured by TD-NMR. The results correlate with gravimetric and photometric references. The oil droplet size obtained by TD-NMR correlates well with static light scattering. The diameter of droplets in emulsions and dried powder both measured by TD-NMR, correlates (r = 0.998), implying that oil droplets embedded in a solid matrix can be measured. Summarising, TD-NMR allows analysis of the microstructure of encapsulated lipid powders, in a rapid, simple and non-destructive way. [ABSTRACT FROM PUBLISHER]

Context: Vitamins have been shown to reduce chemotherapy-related fatigue (CRF) by conserving energy loss both during and after cancer treatment. However, it remains unknown whether this reduction of fatigue interferes with the cancer drugs or alters the effectiveness of these agents.Objectives: The objective was to synthesize vitamin–cisplatin-loaded chitosan nano-particles for chemoprevention and cancer fatigue.Materials and methods: Multi-vitamin (C, D3, and B12)–cisplatin composite nano-formulation called NanoCisVital (NCV) to overcome CRF. The interactions between vitamins and NCV were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and a particle size analyser. The chemo-preventive activity was performed byin vitrobio assays.Results: SEM analysis showed spherical shape and the size is < 225 nm. NCV inhibited the proliferating yeast cells as well as denaturation of bovine serum albumin, and it also reduced the sprouting of new blood vessels in dose-dependent manner.Conclusion: Collectively, these results demonstrate that the NCV particles can be used to reduce CRF without much affecting the anti-cancer properties of cisplatin. [ABSTRACT FROM PUBLISHER]

This study investigates encapsulation efficiency of model drug, encapsulated by magnetic poly d,l-lactic-co-glycolic acid (PLGA) nanoparticles (NPs). This is the following part of our preceding paper, which is referred in this paper as Part I. Magnetic nanoparticles and model drug human serum albumin (HSA)-loaded PLGA NPs were prepared by the double emulsion solvent evaporation method. Among five important process variables, concentration of PLGA and concentration of HSA in the inner aqueous phase along with their cross-effect had the strongest influence on the encapsulation efficiency. Encapsulation efficiency of nanoparticles ranged from 18% to 97% depending on the process conditions. Higher encapsulation efficiencies can be achieved by using low HSA and high PLGA concentrations. The optimization process, carried out by exactmathematical tools using GAMSTM/MINOS software makes it easier to find out optimum process conditions to achieve comparatively high encapsulation efficiency (e.g. 92.3%) for relatively small-sized PLGA NPs (e.g. 155 nm). [ABSTRACT FROM AUTHOR]

A robust experimental design method was developed using a response surface methodology and models to facilitate the development process of retinol solid lipid nanoparticles (SLNs). The SLNs were evaluated to determine how different parameters including lipid and surfactant affect size and encapsulation efficiency. This was conducted using factorial analysis and a robust design (RD) method was used to achieve optimal formulations. Two models were developed based on the RD principle and both mean and variance of the response characteristics were estimated functionally using the least squares method. They proved useful in formulation studies aiming to develop optimum by allowing a systematic and reliable design method. A model for maximizing the overall desirability represented by the geometric mean of all objectives was found to provide a better solution. The newly designed method provides useful information to characterize significant factors and obtain optimum formulations, thereby allowing a systematic and reliable design method. [ABSTRACT FROM AUTHOR]

An integrated approach through coupling response surface method (RSM) and genetic algorithm (GA) was applied to optimize the spray dryer operational condition for production of fish oil microcapsules. The inlet drying air temperature, aspirator rate, and peristaltic pump rate were independent and encapsulation efficiency (EE) and exergy efficiency were dependent variables. RSM was applied to establish the relationship between the independent and dependent variables followed by integrating the developed models using three mathematical approaches and measure the fitness value of GA. Consequently, the optimal drying condition for microencapsulation of fish oil was: inlet drying air temperature = 177.23°C, aspirator rate = 63.93%, and peristaltic pump rate = 14.04% yielding exergy efficiency of 8.10% and EE of 79.14%. The results of confirmation experiments for selected drying condition proved the capability of utilized approach for determination of sustainable and qualified process in fish oil microencapsulation by spray drying. [ABSTRACT FROM AUTHOR]

Microencapsulation is one of the quality preservation techniques of sensitive substances and a method for production of materials with new valuable properties. Microencapsulation is a process of enclosing micron-sized particles in a polymeric shell. There are different techniques available for the encapsulation of drug entities. The encapsulation efficiency of the microparticle or microsphere or microcapsule depends upon different factors like concentration of the polymer, solubility of polymer in solvent, rate of solvent removal, solubility of organic solvent in water, etc. The present article provides a literature review of different microencapsulation techniques and different factors influencing the encapsulation efficiency of the microencapsulation technique. [ABSTRACT FROM AUTHOR]

This work was to compare the encapsulation efficiency and ultrasound-triggered release for protein between microbubbles and liposomes. Bovine serum albumin (BSA) was used as a model. Final ratios between BSA and HPC in microbubbles and liposomes were 1 : 5, 1 : 7 and 1 : 10, respectively. Morphologic characteristics and contrast enhancement of loaded microbubbles and liposomes were measured. Encapsulation efficiency and ultrasound-stimulated release profile were detected. The mean size of loaded microbubbles and liposomes was 3.4 µm and 1.7 µm, respectively. Encapsulation efficiency of microbubbles had an inverse relationship with the ratio between BSA and HPC, while loaded liposomes remained nearly unchanged in the designed range of the ratio between BSA and HPC. Microbubbles resulted in significant enhancement of CnTi images. After ultrasound, more than 90% of the entrapped BSA was released from microbubbles, but less than 5% of BSA released from liposomes. Microbubbles are a promising delivery system for proteins. [ABSTRACT FROM AUTHOR]

Two manufacturing methods and numerous formulative approaches have been evaluated to obtain a stable oral pharmaceutical form of Vitamin A palmitate (VAP), a substance very sensitive to light, temperature, humidity and metal ions. The best results were obtained by formulating VAP, stabilized with butylated hydroxytoluene (BHT), in double layer microcapsules constituted by a core of chitosan, Tween 20, CaCl2 and EDTA surrounded by a first chitosan-alginate membrane and an outer membrane of calcium-alginate. This formulation design enabled the production of beads with high drug loading (42% w/w) and high encapsulation efficiency (94%). The stability of VAP-loaded microcapsules was assessed according to EMEA guidelines. This formulation design showed the best performance in terms of VAP recovery ( t50% > 360 days) after 1 year of storage at room conditions. This is a very important result considering the poor shelf-life (45 days) of pure VAP stabilized with BHT stored at the same conditions. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop and characterize diclofenac sodium loaded-cellulose acetate butyrate microparticles in order to obtain a controlled-release system. The influence of the type of polymer, the volume and composition of the internal phase, drug loading, surfactant concentration and additive added on microparticles characteristics (particle size, encapsulation efficiency, surface morphology and in vitro release profiles) was studied to optimize the microparticles system. The resultant microparticles were evaluated for the recovery, average particle size, drug loading and incorporation efficiency. The microparticles exhibited good flowing nature and compressibility index when compared to pure drug. Dissolution rate of diclofenac sodium in phosphate buffer (pH 6.8) increased with increases in initial drug loading, surfactant concentration and addition of alcohol as co-solvent but decreased with increases in the concentration of additives such as Gantrez® AN or Eudragit S100 in the internal phase. The dissolution data showed a Higuchi diffusion pattern for most of the formulations. About 56-81% reduction in ulcerogenic activity was observed with microparticles containing Eudragit S100 17-25%, based on total polymer concentration, when compared with pure diclofenac sodium. [ABSTRACT FROM AUTHOR]

A recombinant aminopeptidase (90 kDa) of Lactobacillus rhamnosus S93 produced by E. coli was encapsulated in alginate or chitosan-treated alginate beads prepared by an extrusion method. This study investigated the effects of alginate, CaCl2, chitosan concentrations, hardening time, pH and alginate/enzyme ratios on the encapsulation efficiency (EE) and the enzyme release (ER). Chitosan in the gelling solution significantly increased the EE from 30.2% (control) to 88.6% (coated). This polycationic polymer retarded the ER from beads during their dissolution in release buffer. An increase in alginate and chitosan concentrations led to greater EE and lesser ER from the beads. The greatest EE was observed in a pH 5.4 solution (chitosan-CaCl2) during bead formation. Increasing the CaCl2 concentration over 0.1 M neither affected the EE nor the ER. Increasing hardening time beyond 10 min led to a decrease in EE and the alginate:enzyme ratio (3 : 1) was optimal to prevent the ER. [ABSTRACT FROM AUTHOR]

The development of solid lipid nanoparticles (SLN) containing all-trans retinoic acid (RA) is an interesting approach to topical treatment of acne. SLN has potential for controlled release and follicular penetration, which can reduce adverse effects in comparison with conventional formulations. However, the encapsulation efficiency (EE) of RA in SLN is usually low, unless a high surfactant/lipid ratio is used. The aim of this work was to develop SLN with high EE using a low surfactant/lipid ratio. Different formulations of RA-loaded SLN were prepared using glyceryl behenate as lipid matrix. The particle size, EE, zeta potential and differential scanning calorimetry (DSC) were investigated. High EE in SLN was obtained with addition of amines. These results indicate that the utilization of amines is an interesting approach to improve the EE of RA in SLN using a low surfactant/lipid ratio. [ABSTRACT FROM AUTHOR]

To develop a long-acting injectable huperzine A-PLGA microsphere for the chronic therapy of Alzheimer's disease, the microsphere was prepared by using an o/w emulsion solvent extraction evaporation method based on a series of formulation design of the emulsion. The dialysis method was used for release analysis. The encapsulation efficiency and release amount of the microspheres were determined by a UV/VIS spectrophotometer. The morphology of the microspheres was observed by scanning electron microscopy. The distribution of the drug within microspheres was observed by a confocal laser scanning microscope. The results indicated that the PLGA 15?000 microspheres possessed a smooth and round appearance with average particle size of 50?µm or so. The encapsulation percentages of microspheres prepared from PLGA 15?000, 20?000 and 30?000 were 62.75%, 27.52% and 16.63%, respectively. The drug release percentage during the first day decreased from 22.52% of PLGA 30?000 microspheres to 3.97% of PLGA 15?000 microspheres, the complete release could be prolonged to 3 weeks. The initial burst release of microspheres with higher molecular weight PLGA could be explained by the inhomogeneous distribution of drug within microspheres. The encapsulation efficiency of the microspheres improved as the polymer concentration increased in the oil phase and PVA concentration decreased in the aqueous phase. The burst release could be controlled by reducing the polymer concentration. Evaporation temperature had a large effect on the drug release profiles. It had better be controlled under 30°C. Within a certain range of particle size, encapsulation efficiency decreased and drug release rate increased with the reducing of the particle size. [ABSTRACT FROM AUTHOR]

Low encapsulation efficiency, incomplete and erratic release profiles are the most common features of controlled released protein delivery systems employing biodegradable polymers. In the present study, lysozyme as a model protein was encapsulated in biodegradable microspheres using solvent evaporation method and the effect of amphiphilic stabilizer, a basic salt and a lyoprotectant on microparticle formulation was evaluated. Incorporation rat serum albumin (RSA) in the internal aqueous phase during emulsion increased the encapsulation efficiency of lysozyme and maintained the bioactivity. Use of NaHCO3 improved the encapsulation efficiency of lysozyme from 15–94%, but at the cost of reduced in vitro release characteristics. Incorporation of both RSA and NaHCO3 improved the bioactivity of lysozyme and decreased burst release of the protein from the polymer particle, but reduced the encapsulation efficiency from 90–70%. Addition of sucrose in the internal aqueous phase lowered the encapsulation efficiency which was restored by its addition in the external aqueous phase. Maintenance of internal aqueous phase pH close to the iso-electric point of the protein and osmotic balance between the internal aqueous phase and the external aqueous phase during solvent evaporation method helped in better encapsulation of the protein drug. In vitro release of the lysozyme correlated with the effect of different excipients on entrapment in polymer matrix. Entrapment efficiency as high as 76%, low burst effect and high bioactivity of the entrapped lysozyme was observed from the polymer particles. Use of RSA, sucrose and NaHCO3 helped in a co-operative way towards the formulation of particles entrapping bioactive lysozyme. [ABSTRACT FROM AUTHOR]

In this study, betamethasone disodium phosphate-loaded microparticles were fabricated for sustained release using poly(lactide-co-glycolide) (PLGA) by spray drying and emulsion solvent evaporation/extraction techniques. Encapsulation efficiencies ranged from 59-80% using a water-in-oil-in-oil (W/O/O) double emulsion technique and more than 90% for a spray-drying method were obtained. This was a significant improvement compared to fabrication by a water-in-oil-in-water (W/O/W) double emulsion process, which had an encapsulation efficiency of less than 15%. Multiple-phase and biphasic release profiles were observed for microparticles of PLGA 50/50 and PLGA of higher lactide contents, respectively. The PLGA 50/50 hollow microparticles fabricated using the W/O/O double emulsion technique provided a sustained release of betamethasone disodium phosphate over 3 weeks. [ABSTRACT FROM AUTHOR]

Microcapsules containing fragrant oil (Foral oil) were synthesized via the in situ polymerization method using melamine-formaldehyde (M-F) as a wall material. The encapsulation efficiency and other physical properties were analysed with varying formaldehyde/melamine (F/M) mole ratio and pH of emulsion medium. The pH of the reaction medium was varied from 5.0-6.0 and the F/M molar ratio, 2.3 ~ 5.5. Microcapsules containing fragrant oil were synthesized successfully and their particle sizes ranged from 12-15 µm. Encapsulation efficiency of fragrant oil varied from 67-81%. It was found that both pH and F/M molar ratio have an effect on the separation of M-F prepolymer, consequently the morphology of the surface of the microcapsule was changed as well as encapsulation efficiency. The encapsulation mechanism, focusing on the liquid-liquid phase separation of methylolmelamines and formation of M-F precursor particle, was described to explain the surface morphology and encapsulation efficiency. [ABSTRACT FROM AUTHOR]

Linoleic acid was emulsified with gum arabic or maltodextrin at various weight ratios of the acid to the polysaccharide in the presence or absence of a small-molecule emulsifier. The emulsions were spray-dried to produce microcapsules. Emulsions prepared with gum arabic were smaller in droplet size and more stable than those prepared with maltodextrin, and linoleic acid in a gum arabic-based microcapsule was also most resistant to oxidation than that in a maltodextrin-based microcapsule. Although the oil droplet size in the emulsion with maltodextrin decreased and the emulsion stability was improved by addition of a small-molecule emulsifier to linoleic acid, the oxidative stability of the encapsulated linoleic acid was not significantly improved. Encapsulated linoleic acid of small droplet size oxidized more slowly than that of large droplet size. [ABSTRACT FROM AUTHOR]

Water-in-oil-in-water (w/o/w) emulsions encapsulating tryptophan or theophylline were prepared where these compounds are regarded as model drugs. The effects of sodium chloride on the drug entrapment into the w/o/w emulsions and on the separation of aqueous phases were studied. The degree of encapsulation of tryptophan in the w/o/w emulsion increased with the concentration of sodium chloride added in the inner aqueous phase, while it decreased with that in the outer aqueous phase. As for theophylline, although the degree increased with a concentration of sodium chloride in the inner phase, the effect was smaller than that on tryptophan. The difference in the effects between on tryptophan and on theophylline was attributed to their partition coefficients. Theophylline was easily leaked out from the inner phase to the outer aqueous phase after its dissolution and diffusion in the oil phase due to a higher partition coefficient. More than 55%of the aqueous phase was separated from the w/o/w emulsion within 24h, when sodium chloride was not added in the inner aqueous phase. However, the separation was not observed when more than 0.2M sodium chloride was added. To the contrary, sodium chloride added in the outer aqueous phase accelerated the separation. It was, therefore, concluded that sodium chloride in the inner aqueous phase plays an important role in suppression of the separation and in encapsulation of the drug which does not penetrate into the oil membrane. [ABSTRACT FROM AUTHOR]

This workdescribes anovel method toprepare liposomal amikacin composed of soyabean lecithin and cholesterol; these were also prepared using two other methods (cast film method and proliposome method). Encapsulation efficiency was evaluated. Liposomes prepared by the new method, which combines the method of preparing proliposomes with freeze-drying, had the highest encapsulation efficiency. The influence of drug to lipid ratio on the encapsulation efficiency was investigated. The in vitro efflux of amikacin from liposomes with different lecithin: cholesterol ratios was also investigated. [ABSTRACT FROM AUTHOR]