Surface modification of poly (l-lactic acid) microspheres for site-specific delivery of ketoprofen for chronic inflammatory disease

The purpose of this research was to investigate the potential of surface modified Poly (l-lactic acid) (PLA) microspheres as a carrier for site-specific delivery of anti-inflammatory drug, ketoprofen, for the treatment of rheumatoid arthritis. Microspheres were prepared by solvent evaporation method using 20% w/w PLA in methylene chloride and 100 mL of a 2.5% poly vinyl alcohol (PVA) solution. Formulations were optimized for several processing parameters like drug to polymer ratio, stirring rate and volume of preparation medium etc. The surface of PLA microspheres was modified with gelatin to impart fibronectin recognition. The microspheres were characterized by surface morphology, size distribution, encapsulation efficiency, and by in vitro drug release studies. The prepared microspheres were light yellow, discrete, and spherical. Formulation with optimum drug to polymer ratio exhibited smallest vesicle size (43.02), high drug encapsulation efficiency (81.11) and better process yield (83.45). The release of drug was extended up to 24 h with Higuchi pattern of drug release. The in vivo results showed that the gelatin modified formulation reduced paw edema at greater extent than pure drug and PLA microspheres and it could be a promising carrier system for controlled and site-specific delivery of ketoprofen with possible clinical applications.     

Ibuprofen-loaded ethylcellulose/polystyrene microspheres: An approach to get prolonged drug release with reduced burst effect and low ethylcellulose content

The aim of this study was to develop ethylcellulose microspheres for prolonged drug delivery with reduced burst effect. Ethylcellulose microspheres loaded with ibuprofen were prepared with and without polystyrene, which was used to retard drug release from ethylcellulose microspheres. Ibuprofen-loaded ethylcellulose microspheres with a polystyrene content of 0–25% were prepared by the solvent evaporation technique and characterized by drug loading, infrared spectroscopy, differential scanning calorimetry and scanning electron microscopy. The in vitro release studies were performed to study the influence of polystyrene on ibuprofen release from ethylcellulose microspheres. The microspheres showed 28–46% of drug loading and 80–92% of entrapment, depending on polymer/drug ratio. The infrared spectrum and thermogram showed stable character of ibuprofen in the microspheres and revealed an absence of drug polymer interaction. The prepared microspheres were spherical in shape and had a size range of 0.1–4μm. Ethylcellulose/polystyrene micro-spheres showed prolonged drug release and less burst effect when compared to microspheres prepared with ethylcellulose alone. Microspheres prepared with an ethylcellulose/polystyrene ratio of 80:20 gave a required release pattern for oral drug delivery. The presence of polystyrene above this ratio gave release over 24 h. To find out the mechanism of drug release from ethylcellulose/polystyrene microspheres, the data obtained from in vitro release were fitted in various kinetic models. High correlation was obtained in Higuchi and Korsmeyer-Peppas models. The drug release from ethylcellulose/polystyrene microspheres was found to be diffusion controlled.     

5-Fluorouracil-loaded microspheres prepared by spray-drying poly(D,L-lactide) and poly(lactide-co-glycolide) polymers: Characterization and drug release

5-Fluorouracil (5-FU), a hydrosoluble anti-neoplastic drug, was encapsulated in microspheres of poly(D,L-lactide) (PLA) and poly(lactide-co-glycolide) (PLGA) polymers using the spray-drying technique, in order to obtain small size microspheres with a significant drug entrapment efficiency. Drug-loaded microspheres included between 47?±?11 and 67?±?12?µg 5-FU?mg^?1 microspheres and the percentage of entrapment efficiency was between 52?±?12 and 74?±?13. Microspheres were of small size (average diameter: 0.9?±?0.4–1.4?±?0.8?µm microspheres without drug; 1.1?±?0.5–1.7?±?0.9?µm 5-FU-loaded microspheres) and their surface was smooth and slightly porous, some hollows or deformations were observed in microspheres prepared from polymers with larger T_g. A fractionation process of the raw polymer during the formation of microspheres was observed as an increase of the average molecular weight and also of T_g of the polymer of the microspheres. The presence of 5-FU did not modify the T_g values of the microspheres. Significant interactions between the drug and each one of the polymers did not take place and total release of the included drug was observed in all cases. The time needed for the total drug release (28–129?h) was in the order PLA?>?PLGA 75/25?>?PLGA 50/50. A burst effect (17–20%) was observed during the first hour and then a period of constant release rate (3.52?±?0.82–1.46?±?0.26?µg 5-FU?h^?1 per milligram of microspheres) up to 8 or 13?h, depending on the polymer, was obtained.     

Controlled release of nifedipine from gelatin microspheres and microcapsules: in vitro kinetics and pharmacokinetics in man

Abstract

Nifedipine was embedded in a gelatin matrix to develop a prolonged release dosage form. The effects of polymer/drug ratio, size of the beads, cross-linking with formaldehyde and ethylcellulose coating of the gelatin microspheres on the in vitro release rate of the drug were investigated. The data were analysed according to different laws that can govern the release mechanism: first-order, Higuchi square root of time, spherical matrix and zero-order. The in vitro release kinetics of nifedipine from gelatin microspheres were mainly first-order; from formaldehyde hardened gelatin microspheres, complied with the diffusion model for a spherical matrix, and from ethylcellulose-coated gelatin microspheres, obeyed zero-order kinetics. These findings suggest the possibility of modifying the formulation in order to obtain the desired controlled release of the drug for a convenient oral sustained delivery system. The pharmacokinetic parameters of nifedipine, after adminstration of a single oral dose of nifedipine-loaded hardened gelatin microspheres to volunteers, suggest that the preparation can be considered as a sustained release delivery system for nifedipine.     

Targeted delivery of diclofenac sodium via gelatin magnetic microspheres formulated for intra-arterial administration

In the present work, we have attempted to deliver diclofenac sodium to a target site by intra-arterial injection of gelatin magnetic microspheres and subsequent localization using an external magnet. Drug-loaded magnetic microspheres were prepared by emulsification/cross-linking method, characterized by drug loading, magnetite content, size distribution, optical microscopy, scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) analysis, differential scanning calorimetry (DSC), X-ray diffraction (XRD), absence of glutaraldehyde by gas chromatography, and in vitro release studies. The targeting efficiency and the therapeutic efficacy of microspheres were studied in vivo in rabbits. The microspheres showed drug loading of 9.1, 18.7, 24.9% w/w, magnetite content of 27.8–28.9% w/w with an average size range of 25–30.6 μm, depending upon the drug–polymer ratio. They were spherical in nature as evidenced by optical microscopy and SEM. FT-IR, DSC, and XRD studies revealed the absence of drug–polymer interaction. Gas chromatography confirmed the absence of residual glutaraldehyde. The microspheres were able to prolong the drug release over 24–30 days and the application of sonication during in vitro release study has slightly increased the release rate. After intra-arterial administration of microspheres, 77.7% of injected dose was recovered at the target site which revealed good targeting efficiency. The microspheres effectively reduced joint swelling, but lesser extent than the oral diclofenac sodium in high dose, in antigen induced arthritic rabbits without producing gastric ulceration which was observed in rabbits treated with oral diclofenac sodium.     

Preparation,characterization and in vitro release properties of ibuprofen-loaded microspheres based on polylactide,poly(϶-caprolactone) and their copolymers

In this paper, ibuprofen was encapsulated into microspheres by oil-in-water (o/w) emulsion solvent evaporation method. Biodegradable polymers with certain compositions and characteristics such as polylactide (PLA), poly(?-caprolactone) (PCL) and their block copolymer were used to prepare the microspheres. The results indicate that, under the same processing conditions, the drug entrapment efficiency was similar (～80%) for microspheres prepared with PLA and P(LA-b-CL) (78.7/21.3 by mole), but it was only 25.4% for PCL microspheres. The in vitro drug release rate decreased in the order of PCL, P(LA-b-CL) (78.7/21.3 by mole) and PLA microspheres. PCL microspheres showed more serious burst release during the first day (almost 80%) than P(LA-b-CL) (50%) and PLA microspheres (18%). The complete ibuprofen release duration from the last two kinds of microspheres exceeded 1 month. Characterization of the microspheres by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and polarized optical microscope (POM) revealed that ibuprofen was amorphous in PCL microspheres and partially crystalline in P(LA-b-CL) and PLA microspheres. The different release behaviour of ibuprofen from the three kinds of microspheres could be attributed to the different crystallinity of the studied polymers and drug dispersion state in polymer matrices. All the above results suggest that the copolymer with a certain ratio of lactide to ?-caprolactone could have potential applications for long-term ibuprofen release.     

Development of gelatin microspheres loaded with diclofenac sodium for intra-articular administration

We have previously reported on the targeting of diclofenac sodium in joint inflammation using gelatin magnetic microspheres. To overcome complications in the administration of magnetic microspheres and achieve higher targeting efficiency, the present work focuses on the formulation of gelatin microspheres for intra-articular administration. Drug-loaded microspheres were prepared by the emulsification/cross-linking method, characterized by drug loading, size distribution, scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), X-ray diffraction (XRD), gas chromatography, and in vitro release studies. The targeting efficiency of microspheres was studied in vivo in rabbits. The microspheres showed drug loading of 9.8, 18.3, and 26.7% w/w with an average size range of 37–46 µm, depending upon the drug–polymer ratio. They were spherical in nature and free from surface drug as evidenced by the SEM photographs. FT-IR, DSC, and XRD revealed the absence of drug–polymer interaction and amorphous nature of entrapped drug. Gas chromatography confirms the absences of residual glutaraldehyde. The formulated microspheres could prolong the drug release up to 30 days in vitro. About 81.2 and 43.7% of administered drug in the microspheres were recovered from the target joint after 1 and 7 days of postintra-articular injection, respectively, revealing good targeting efficiency.     

Characterization of Poly(glycolide-co-D,L-lactide)/Poly(D,L-lactide) Microspheres for Controlled Release of GM-CSF

Purpose. This study describes the preparation and characterization of a controlled release formulation of granulocyte-macrophage colony-stimulating factor (GM-CSF) encapsulated in poly(glycolide-co-D,L-lactide) (PLGA) and poly(D,L-lactide) (PLA) microspheres. Methods. GM-CSF was encapsulated in PLGA/PLA microspheres by a novel silicone oil based phase separation process. Several different blends of PLGA and low molecular weight PLA were used to prepare the microspheres. The microspheres and the encapsulated GM-CSF were extensively characterized both in vitroand in vivo. Results. Steady release of GM-CSF was achieved over a period of about one week without significant 'burst' of protein from the microspheres. Analysis of microsphere degradation kinetics by gel permeation chromatography (GPC) indicated that low molecular weight PLA enhanced the degradation of the PLGA and thereby affected release kinetics. GM-CSF released from the microspheres was found to be biologically active and physically intact by bioassay and chromato-graphic analysis. Analysis of serum from mice receiving huGM-CSF indicated that the GM-CSF was biologically active and that a concentration of greater than 10 ng/mL was maintained for a period lasting at least nine days. MuGM-CSF was not detected followingin vivo administration of muGM-CSF microspheres. The tissues of mice receiving muGM-CSF microspheres were characterized by infiltration of neutrophils, and macrophages which were in significant excess of those found in mice administered with placebo controls (i.e. microspheres without GM-CSF). Conclusions. This study demonstrates the influence of formulation parameters on the encapsulation of GM-CSF in PLGA/PLA microspheres and its controlled release in biologically active form. The intense local tissue reaction in mice to muGM-CSF microspheres demonstrates the importance of the mode of delivery on the pharmacologic activity of GM-CSF.     

Ondansetron-loaded biodegradable microspheres as a nasal sustained delivery system: In vitro/in vivo studies

The aim of this study was to prepare ondansetron-loaded biodegradable microspheres as a nasal delivery system. Microspheres were prepared with emulsification/spray-drying technique using poly(d,l-lactide) (PLA) and two different types of poly(d,l-lactide-co-glycolide) (PLGA). The effect of the type of organic solvent (dichloromethane (DCM) or a mixture of DCM and ethyl acetate) on the microsphere characteristics was also examined. The prepared microspheres were evaluated with respect to the morphological properties, particle size, zeta potential, drug loading efficiency, and in vitro drug release. The mean particle size (d₅₀) of microsphere formulations was ranged from 11.67–25.54 μm, indicating suitable particle size for nasal administration. All microspheres had low drug loading efficiency in the range of 12.28–21.04%. The results indicated that particle size of microspheres were affected by both type of polymer and organic solvent, however drug loading efficiency of microspheres were affected by only the type of organic solvent used. All microspheres were negatively charged due to the polymers (PLA or PLGA) used. A prolonged in vitro drug release profile was observed for 96?h. Based on in vitro data, the selected microsphere formulation has been applied via nasal route to rats in vivo. Following nasal administration of ondansetron-loaded microsphere to rats, ondansetron plasma levels were within a range of 30–48?ng/mL during 96?h, indicating a sustained drug delivery pattern and relatively a constant plasma drug concentration level. The results suggested that biodegradable microspheres prepared with emulsification/spray-drying technique could be considered to deliver ondansetron via nasal route to obtain a prolonged release.     

Utilization of an Amorphous Form of a Water-Soluble GPIIb/IIIa Antagonist for Controlled Release from Biodegradable Microspheres

Purpose. We prepared injectable microspheres for controlled release of TAK-029, a water-soluble GPIIb/IIIa antagonist and discussed the characteristics of controlled release from microspheres. Methods. Copoly(dl-lactic/glycolic)acid (PLGA) microspheres were used for controlled release of TAK-029 [4-(4-amidinobenzoylglycyl)-3-methoxycarbonyl-2-oxopiperazine-l-acetic acid]. They were prepared with a solid-in-oil-in-water (S/O/W) emulsion solvent evaporation technique using either a crystalline form or an amorphous form of the drug. Results. An amorphous form of TAK-029 gave more homogeneous S/O dispersion and higher viscosity than its crystalline form when added to dichloromethane solution of PLGA, resulting in a high drug entrapment into microspheres and a well-controlled release of the drug. Additions of sodium chloride into an external aqueous phase and L-arginine into an oil phase also increased entrapment of the drug, and reduced initial burst of the drug from the microspheres. The micro-spheres demonstrated a desirable plasma level profile in therapeutic range (20–100 ng/ml) for 3 weeks in rats after single subcutaneous injection. Conclusions. A well-controlled release of TAK-029, a water-soluble neutral drug, with small initial burst was achieved by utilizing its amorphous form as a result of possible interaction with PLGA and L-arginine.     

Preparation and characterization of ethylcellulose microspheres containing 5-fluorouracil

Abstract

Ethylcellulose microspheres containing 5-fluorouracil (5-FU) were prepared by a solvent evaporation technique using light mineral oil as the continuous phase. The drug was suspended in the acetone solution of the polymer. Three drug/polymer ratios (1/1, 1/2 and 1/3) were utilized. The microspheres were studied with respect to size, drug content and surface characteristics; the higher the polymer content, the smoother the microspheres. The drug was suspended in the polymer and the drug loading was important (more than 90%) with the three types of microspheres. In vitro dissolution studies in phosphate buffer showed that the 5-FU release was dependent on the drug/polymer ratio for the 400–500 üm granulometric fraction.     

Formulation and evaluation of flurbiprofen-loaded genipin cross-linked gelatin microspheres for intra-articular delivery

Oral and parenteral formulations are challenging to produce therapeutic concentration of flurbiprofen in the joints. This encourages for the development of formulation for long term drug retention in the joint through intra-articular (i. a.) administration. In this study, genipin cross-linked gelatin microspheres of flurbiprofen were prepared for i. a. delivery. The microspheres were prepared using emulsification-homogenization-cross-linking method by changing the experimental variables such as concentration of cross-linker, cross-linking time and cross-linking temperature. The microspheres showed drug entrapment up to 76.19% with a mean particle size range of 5.91–8.19 µm. The degree of cross-linking and water-soluble fraction were 8.27–59.33% and 12.29–81.23%, respectively. SEM confirmed smooth surface and spherical shape of the microspheres. FTIR and ¹³C-NMR confirmed cross-linking of gelatin by genipin. No chemical change in encapsulated drug was observed by FTIR and TGA. DSC and XRD indicated the molecular dispersion of drug within microspheres. Optimized microspheres could prolong the drug release for more than 108?h with anomalous transport. Histopathology confirmed the biocompatibility of microspheres in the rat (Wistar) knee joint. After 96?h of i. a. injection, significant higher amount (42.56%) of administered drug in cross-linked microspheres was recovered than uncross-linked microspheres (8.27%) confirming better drug retention efficiency (p < 0.01).     

Preparation and Characterization of Oxybenzone-Loaded Gelatin Microspheres for Enhancement of Sunscreening Efficacy

The objective of our present study was to prepare and evaluate gelatin microspheres of oxybenzone to enhance its sunscreening efficacy. The gelatin microspheres of oxybenzone were prepared by emulsion method. Process parameters were analyzed to optimize the formulation. The in vitro drug release study was performed in pH 7.4 using cellulose acetate membrane. Microspheres prepared using oxybenzone:gelatin ratio of 1:6 showed slowest drug release and those prepared with oxybenzone:gelatin ratio of 1:2 showed fastest drug release. The gelatin microspheres of oxybenzone were incorporated in aloe vera gel. Sun exposure method using sodium nitroprusside solution was used for in vitro sunscreen efficacy testing. The formulation C₅ containing oxybenzone-bearing gelatin microspheres in aloe vera gel showed best sunscreen efficacy. The formulations were evaluated for skin irritation test in human volunteers, sun protection factor, and minimum erythema dose in albino rats. These studies revealed that the incorporation of sunscreening agent–loaded microspheres into aloe vera gel greatly increased the efficacy of sunscreen formulation more than four times.     

Preparation and investigation the release behaviour of wax microspheres loaded with salicylic acid

Salicylic acid-beeswax microspheres were prepared by melt dispersion technique. The effects of formulation parameters on the microscopic characteristic, drug loading and cumulative amount of released drug were investigated by experimental design. Results showed that all of the microparticles were spherical with porous surfaces. The average size of microspheres was 24–48 µm, the drug content was in the range of 22–45% and the encapsulation efficiency was 46–93%. Drug loading was influenced by emulsification speed as a main factor. All the microspheres had a burst release initially. The emulsifier concentration did not have a significant effect on drug release. The release behaviour of microspheres conformed best to Korsmeyer-Peppas semi-empirical model and the release of SA from beeswax microspheres was Fickian (n < 0.45).     

Preparation,characterization and performance evaluation of neomycin-HSA microspheres

Abstract

Human serum albumin microspheres containing neomycin sulphate were prepared using emulsion polymerization and polymer dispersion techniques. The many variables which may affect the shape, size, stability, release of the drug from the microspheres such as internal phase to external phase volume ratio, human serum albumin content, stirring rate, polymer content and stabilizing agent concentration, were studied. Unlike the microspheres prepared by the emulsion polymerization technique, polymer dispersion stabilised microspheres were uniform in size and shape with a narrow range of size distribution. In vitro release of neomycin sulphate from albumin microspheres was studied using the dialysis cell method. The drug release from microspheres followed Q versus (t)^?1/2 linear relationship. The in vivo distribution studies on prepared microspheres revealed that the localization takes place preferably in lung tissues, liver, spleen and kidney and is found to be dependent on the microsphere size. On administration of microspheres of 3-6 μm size, approximately 55 per cent of administered drug could be localized in the lungs.     

Design and characterization of chitosan-alginate microspheres for ocular delivery of azelastine

Abstract

The use of mucoadhesive biopolymers is one of the best approaches to prolong the drug residence inside the cul-de-sac, consequently increasing the bioavailability. Thus, the focus of this work was to develop mucoadhesive microspheres to overcome the limitations of ocular drug delivery. The chitosan-sodium alginate microspheres of azelastine hydrochloride were fabricated using modified ionotropic gelation technique. The particle size, zeta potential, entrapment efficiency and drug release kinetics were evaluated and characterized by SEM, FT-IR, DSC, in vitro mucoadhesion and in vivo study. The microspheres had average particle size in the range of 3.55 to 6.70?µm and zeta potential +24.55 to +49.56?mV. The fabricated microspheres possess maximum drug entrapment of 73.05% with 65% mucin binding efficiency and revealed a controlled release over the 8-h period following a non-Fickian diffusion. SEM showed that microspheres were distinct solid with irregular shape. FT-IR and DSC results concluded the drug entrapment into microspheres. In vivo studies on ocular rat model revealed that azelastine microspheres had better efficacy. Chitosan sodium alginate microspheres prepared were in particle size range suitable for ocular purpose. In vitro release and in vivo efficacy studies revealed that the microspheres were effective in prolonging the drug’s presence in cul de sac with improved therapeutic efficacy.     

Positively Charged Gelatin Microspheres as Gastric Mucoadhesive Drug Delivery System for Eradication of H. pylori

Gastric mucoadhesive drug delivery systems are very promising for eradication of Helicobacter pylori (H. pylori), a spiral bacterium that resides in the gastric mucus layer and at the mucus- epithelial cell interface. New positively charged biodegradable microspheres were prepared using aminated gelatin by surfactantfree emulsification in olive oil, followed by a cross-linking reaction with glutaraldehyde. The amino group contents of the modified gelatin and the microspheres were determined using a 2,4,6-trinitrobenzenesulfonic acid method. With the increase of glutaraldehyde concentration, the amino group content of the microspheres decreased accordingly. The influence of glutaraldehyde concentration, cross-linking reaction time, drug-loading patterns, and type of release media on the in vitro release characteristics of amoxicillin from the microspheres was investigated. Amoxicillin release rate from the modified gelatin microspheres was significantly reduced compared with that from gelatin microspheres. Furthermore, the release was decreased with the increase of glutaraldehyde concentration and/or cross-linking time. On the other hand, a faster release was observed in a lower pH release medium and/or using a lower pH solution for amoxicillin loading. The gastric mucoadhesive properties of the microspheres were evaluated using RITC-labeled microspheres in an isolated rat stomach. The gastric mucoadhesion of the modified gelatin microspheres was markedly improved compared with that of gelatin microspheres. The modified gelatin microsphere proves to be a possible candidate delivery system for the effective eradication of H. pylori.     

Polyanhydride Mierospheres that Display Near-Constant Release of Water-Soluble Model Drug Compounds

A new method to prepare polyanhydride microspheres capable of near-constant sustained release of low molecular weight, water-soluble molecules is presented. The polyanhydrides used were poly-(fatty acid dimer) (PFAD), poly(sebacic acid) (PSA), and their co-polymers [P(FAD-SA)]. Acid orange 63 (AO), acid red 8 (AR), and p-nitroaniline, were used as model release molecules. P(FAD-SA) microspheres containing the molecules with or without gelatin were prepared by a modified solvent evaporation method using a double emulsion. The microspheres were spherical with diameters of 50–125 µm and encapsulated more than 85% of the molecule, irrespective of the compound used. Near-zero-order degradation kinetics were observed for 5 days as judged by sebacic acid (SA) release. Microsphere degradation was pH sensitive, being enhanced at high pH, and became more stable in acidic conditions, irrespective of the incorporation of gelatin in the matrix. For the gelatin-free microspheres, a close correlation of SA release and AO release was observed (2% loading), suggesting a release mechanism that was controlled dominantly by degradation. However, the incorporation of gelatin into the microsphere significantly extended the periods of molecule release from P(FAD-SA) microspheres, although the degradation profile of the microspheres themselves was quite similar to that of gelatin-free microspheres. It is possible that an interaction between FAD monomers and gelatin molecules causes continued release, even after the polymer matrix completely degrades (even after complete degradation, FAD monomers remain because of their poor water solubility). Thermal analysis of polyanhydride microspheres at different degradation stages demonstrated that a crystalline structure was formed between gelatin and the FAD monomers produced with microsphere degradation. This gelatin effect on the extended period of drug release was not observed for microspheres prepared from other polyanhydrides: poly (sebacic acid) and its co-polymer of bis(p-carboxyphenoxy) propane and sebacic acid. It is therefore likely that the crystalline structure formed between gelatin and FAD monomers may function as a reservoir for water-soluble drugs, leading to an extended period of molecule release from the gelatin-loaded P(FAD-SA) microspheres.     

Microencapsulation of Hepatitis B Core Antigen for Vaccine Preparation

Purpose. To prepare poly(lactide-co-glycolide)(PLGA) microspheres containing recombinant hepatitis B core antigen (HBcAg; Mw = 3,600,000) by a w/o/w emulsion/solvent evaporation method and evaluate the possibility of this system as a potent long-acting carrier for hepatitis B core antigen in mice. Methods. Various additives had been incorporated in the internal aqueous phase during the process of microencapsulating HBcAg, HBcAg antigenicity in the medium extracted from the prepared microspheres were measured by ELISA. Shape confirmation of the HBcAg antigen was performed by a sucrose gradient velocity centrifugal technique. For in vivo study, prepared microspheres were administered subcutaneously to Balb/C mice, and the serum IgG level was determined by ELISA. Results. The inactivation of HBcAg by methylene chloride was dramatically reduced by the addition of gelatin (4–8% (w/v)) to the internal aqueous phase during the preparation. Further improvement of the loading efficiency to almost 61% resulted with cooling (4°C). The prepared microspheres (4.27 m ± 1.23 m) containing 0.15% HBcAg displayed burst release (50–60% within 2 days). In subcutaneous inoculation, the adjuvant effect of PLGA microspheres was almost the same as that of the complete Freund's adjuvant. Whereas oral inoculation using the microspheres was not effective. Conclusions. The pH of the added gelatin seemed to be the key to the stabilization of HBcAg from various stability tests and CD spectrum study. Finally, the possibility of using this system as a potent long-acting hepatitis B vaccine was demonostrated.     

Chitosan microspheres of aceclofenac: In vitro and in vivo evaluation

The objective of this investigation was to achieve controlled drug release of Aceclofenac (ACE) microspheres and to minimize local side-effects in the gastrointestinal tract (GIT). Sustained release chitosan microspheres containing ACE were prepared using double-emulsion solvent evaporation method (O/W/O). Chitosan microspheres were prepared by varying drug to polymer ratio (1:3, 1:4, 1:5 and 1:6). Microspheres were characterized for morphology, swelling behavior, mucoadhesive properties, FTIR and DSC study, drug loading efficiency, in vitro release, release kinetics, and in vivo study was performed on rat model. ACE-loaded microspheres were successfully prepared having production yield, 57–70% w/w. Drug encapsulation efficiency was ranging from 53–72% w/w, Scanning electron microscopy (SEM) revealed particle size of microspheres was between 39 and 55 μm. FTIR spectra and DSC thermograms demonstrated no interaction between drug and polymer. The in vitro release profiles of drug from chitosan microspheres showed sustained-release pattern of the drug in phosphate buffer, pH 6.8. In vitro release data showed correlation (r² > 0.98), good fit with Higuchi/Korsmeyer-Peppas models, and exhibited Fickian diffusion. ACE microspheres demonstrated controlled delivery of aceclofenac and apparently, no G.I.T. erosion was noticed.