Release Microspheres Research Articles

Preparation of Sustained Release Microspheres of Aceclofenac: Characterization & in-vivo studies

Objective: To explore the sustained drug release model of Aceclofenac from microspheres to establish the result of hydrogel forming mucoadhesive polymers on drug release. Methods: Microspheres were produced by Emulsion solvent evaporation method using Carboxy Methyl cellulose (CMC) and Carbopol 934P (CP) as hydrogel forming polymers. Results and Discussion: Mucoadhesive sustained release microspheres of Aceclofenac were prepared using carboxymethyl cellulose sodium and carbomer 934P hydrogel forming polymers. Carboxymethyl cellulose sodium and Carbomer 934P were used in 1/3 and 1/6w/w proportion in the preparation. Scanning electron microscopy revealed the uneven outer surface of the microspheres. Invitro dissolution test was carried out in simulated gastric fluid pH 1.2 and simulated intestinal fluid pH 6.8. Release of Aceclofenac from microspheres was found sustained, dependent on the erosion of crosslinking of carbopol 934P. Invitro mucoadhesive study was done on fresh stomach mucosa of chicken and chicken egg shell membrane. Invivo gastroenteric conveyance of microspheres was done in Male Sprague-Dawley rats. Conclusion: Invitro drug release is sustained for the period of 14 hrs. In-vitro Muco-adhesion evaluation can be done either on chicken stomach mucous membrane or chicken eggshell membrane.

Design, optimization and characterizations of chitosan fortified calcium alginate microspheres for the controlled delivery of dual drugs

Periodontal disease is chronic, highly prevalent infectious disease that requires prolonged and controlled delivery of antimicrobial agents into pockets. To achieve this objective, dual antimicrobials encapsulated chitosan fortified calcium alginate (CS-Ca-SA) microspheres were formulated by application of Plackett-Burman factorial design. The microspheres were optimized for particle size (PS), entrapment efficiency (EE) and drug release. The optimized microspheres presented average PS of 74–461 µm and EE of 62.45–86.20% with controlled drug delivery for 120 hours. FTIR disclosed successful complexation between SA and CS. DSC and XRD studies showed changes in the crystallinity of drugs in microspheres. Shape factor and SEM demonstrated spherical to pear-shaped microspheres. Release exponent >0.43 and high diffusion coefficients revealed non-Fickian-based diffusion-limited drug release. CS-Ca-SA microspheres exhibited surface pH of 6.5 ± 0.5, moderate swelling, less erosion and improved mucoadhesion over Ca-SA microspheres. Also, significant antimicrobial activity against Escherichia coli and Staphylococcus aureus and cytocompatibility with L929 cell lines were observed. Further, microspheres exhibited long-term stability on refrigeration. The outcomes of study supported the potential of dual polymer and dual drug-based biodegradable, stable, non-toxic, mucoadhesive, controlled and prolonged drug release microspheres as more patient compliant by administration into periodontal pockets for the management of periodontal disease.

FORMULATION AND IN-VITRO-IN-VIVO EVALUATION OF ALGINATE-CHITOSAN MICROSPHERES OF GLIPIZIDE BY IONIC GELATION METHOD

Objective: The present work is aimed to formulate and evaluate alginate-chitosan microspheres of glipizide for the effective use in the treatment of diabetes.Methods: Sustained release microspheres were prepared by gentle mixing of polymers in water phase with drug by agitation. The polymers used for preparation were sodium alginate and chitosan, which was extruded into 5% calcium chloride solution to produce microspheres by ionic gelation method.Results: Single unit dosage form of Glipizide causes gastric irritation. To convert it in to the multiple unit dosage form will release the drug evenly throughout the stomach which suppresses the irritation. The aim of study towards formulation and evaluation of alginate-chitosan microspheres, which can provide sustained release of the model drug. It shows better in-vitro and in-vivo activity than conventional dosage forms. The work also aims to study various parameters affecting the behavior of microspheres in oral dosage form. Conclusion: Drugs that are simply absorbed from the gastrointestinal tract (GIT) and having a short half life are eliminated rapidly from the blood flow. To avoid this trouble, the oral sustained release (SR) has been developed as these will release the drug slowly in to the GIT and maintain a stable drug concentration in the serum for a longer period of time.

FORMULATION AND EVALUATION OF SUSTAINED RELEASE MICROSPHERES OF ATORVASTATIN USING CHITOSAN AND ALGINATE

Certain problems regarding the drugs like high first pass metabolism, also the bioavailability of the certain drugs varies due to instability in acidic environment of stomach. Hence, to resolve such problems the drug should be incorporated in the microspheres for sustained release using a suitable polymer. Natural polymer like chitosan gained great interest in pharmaceutical sector because of its advantages like biodegradability, biocompatibility, non-toxicity, non-immunogenicity and low cost. In the present study, formulation and evaluation of polymeric microspheres of Atorvastatin Calcium was carried out and the release profile of such drug using the alginate and chitosan was studied. Microspheres were prepared for sustained release of drug using chitosan and alginate polymers by ionotropic gelation method. Microspheres were spherical in shape, having good flow properties and further its encapsulation efficiency, swelling index, micromeritic study, in- vitro drug release study and stability studies were performed in order to characterize microspheres. Three different concentrations of sodium alginate (1%, 2% and 3%) were used. The higher encapsulation efficiency was observed as the concentration of alginate increased. This is due to the greater availability of active calcium binding sites in the polymeric chains and consequently the greater degree of cross linking. The highest encapsulation efficiency (88.36) was achieved with 2% w/v sodium alginate in combination with 3% chitosan (F6). Among the prepared formulations with respect to the entrapment efficiency, swelling studies and in vitro drug release, the alginate-chitosan microspheres prepared by ionotropic gelation using calcium chloride found to be better than ionically cross linked alginate spheres alone. Therefore, dual cross-linked, microspheres are promising carrier for sustained release of drug.

Experimental study on loading naringin composite scaffolds for repairing rabbit osteochondral defects

To investigate the performance of loading naringin composite scaffolds and its effects on repair of osteochondral defects. The loading naringin and unloading naringin sustained release microspheres were prepared by W/O/W method; with the materials of the attpulgite and the collagen type I, the loading naringin, unloading naringin, and loading transforming growth factor β 1 (TGF-β 1) osteochondral composite scaffolds were constructed respectively by "3 layers sandwich method". The effect of sustained-release of loading naringin microspheres, the morphology of the composite scaffolds, and the biocompatibility were evaluated respectively by releasing in vitro, scanning electron microscope, and cell counting kit 8. Forty Japanese white rabbits were randomly divided into groups A, B, C, and D, 10 rabbits each group. After a osteochondral defect of 4.5 mm in diameter and 4 mm in depth was made in the intercondylar fossa of two femurs. Defect was not repaired in group A (blank control), and defect was repaired with unloading naringin composite scaffolds (negative control group), loading naringin composite scaffolds (experimental group), and loading TGF-β 1 composite scaffolds (positive control group) in groups B, C, and D respectively. At 3 and 6 months after repair, the intercondylar fossa was harvested for the general, HE staining, and toluidine blue staining to observe the repair effect. Western blot was used to detect the expression of collagen type II in the new cartilage. Loading naringin microspheres had good effect of sustained-release; the osteochondral composite scaffolds had good porosity; the cell proliferation rate on loading naringin composite scaffold was increased significantly when compared with unloading naringin scaffold ( P<0.05). General observation revealed that defect range of groups C and D was reduced significantly when compared with groups A and B at 3 months after repair; at 6 months after repair, defects of group C were covered by new cartilage, and new cartilage well integrated with the adjacent cartilage in group D. The results of histological staining revealed that defects were filled with a small amount of fibrous tissue in groups A and B, and a small amount of new cartilage in groups C and D at 3 months after repair; new cartilage of groups C and D was similar to normal cartilage, but defects were filled with a large amount of fibrous tissue in groups A and B at 6 months after repair. The expression of collagen type II in groups C and D was significantly higher than that in groups A and B ( P<0.05), but no significant difference was found between groups C and D ( P>0.05). Loading naringin composite scaffolds have good biocompatibility and effect in repair of rabbit articular osteochondral defects.

Modified dextran, heparin-based triggered release microspheres for cardiovascular delivery of therapeutic drugs using protamine as a stimulus

In this study, we describe the synthesis of an amine-modified acetalated dextran polymer, which is combined with heparin (HP) as the basis for a novel controlled release system. Dextran-amine (DEXAM) conjugates, synthesised using reductive amination, were incorporated into DEXAM/HP microspheres. HP binds to positively charged ammonium ions of the DEXAM conjugates, contributing to the structural integrity of the microspheres. Crystal violet (CV) was encapsulated inside DEXAM/HP microspheres as a model drug to test the system. Protamine with a high affinity for HP functioned as a trigger to release CV. DEXAM/HP microspheres were characterised by particle size, encapsulation efficiency, scanning electron microscope images, and in vitro release profile. Release of CV from microspheres varied with primary amine content of DEXAM conjugates, amount of HP, and concentration of protamine added. The system is considered for controlled delivery of agents without the necessity of chemical modification.

Mechanisms of in vivo release of triamcinolone acetonide from PLGA microspheres

Little is known about the underlying effects controlling in vitro-in vivo correlations (IVIVCs) for biodegradable controlled release microspheres. Most reports of IVIVCs that exist are empirical in nature, typically based on a mathematical relationship between in vitro and in vivo drug release, with the latter often estimated by deconvolution of pharmacokinetic data. In order to improve the ability of in vitro release tests to predict microsphere behavior in vivo and develop more meaningful IVIVCs, the in vivo release mechanisms need to be characterized. Here, two poly(lactic-co-glycolic acid) (PLGA) microsphere formulations encapsulating the model steroid triamcinolone acetonide (Tr-A) were implanted subcutaneously in rats by using a validated cage model, allowing for free fluid and cellular exchange and microsphere retrieval during release. Release kinetics, as well as mechanistic indicators of release such as hydrolysis and mass loss, was measured by direct analysis of the recovered microspheres. Release of Tr-A from both formulations was greatly accelerated in vivo compared to in vitro using agitated phosphate buffered saline +0.02% Tween 80 pH7.4, including rate of PLGA hydrolysis, mass loss and water uptake. Both microsphere formulations exhibited erosion-controlled release in vitro, indicated by similar polymer mass loss kinetics, but only one of the formulations (low molecular weight, free acid terminated) exhibited the same mechanism in vivo. The in vivo release of Tr-A from microspheres made of a higher molecular weight, ester end-capped PLGA displayed an osmotically induced/pore diffusion mechanism based on confocal micrographs of percolating pores in the polymer, not previously observed in vitro. This research indicates the need to fully understand the in vivo environment and how it causes drug release from biodegradable microspheres. This understanding can then be applied to develop in vitro release tests which better mimic this environment and cause drug release by the relevant mechanistic processes, ultimately leading to the development of mechanism based IVIVCs.

Nefopam hydrochloride loaded microspheres for post-operative pain management: synthesis, physicochemical characterization and in-vivo evaluation

Once-daily oral dosage of nefopam hydrochloride loaded sustained release microspheres (NPH-MS) was investigated as novel therapeutic strategy for post-operative pain management. Microspheres were synthesized using poly-3-hydroxybutyrate and poly-(ɛ-caprolactone) by double emulsion solvent evaporation technique. NPH-MS were characterized through FTIR, PXRD and SEM. In-vitro drug release study revealed sustained behavior till 24 h. Haemolysis was <5% which signified haemocompatibility of formulation. ED50 in rat tail-flick anti-nociceptive test was found ∼18.12 mg/kg. In post-operative pain model, reversal of mechanical allodynia and thermal hyperalgesia by NPH-MS was statistically significant (p < .001) as compared with NPH till 24 h post-dose.

Formulation and evaluation of sustained release saxagliptin microspheres by ionotropic gelation method

The objective of the current investigation is to reduce dosing frequency and improve patient compliance by designing and systematically evaluating sustained release microspheres of an antidiabetic agent, saxagliptin. Saxagliptin microspheres were formulated using sodium alginate as the controlled release polymer by ionotropic gelation technique. The polymer sodium alginate alone and along with different coating polymers like pectin, ethyl cellulose was used in different ratios (1:1,1:1.5, 1:2 ) to formulate batches F1 to F9. The resulting microspheres were evaluated for particle size, densities, flow properties, morphology, recovery yield, drug content, drug entrapment efficiency and in vitro drug release behavior. The formulated microspheres were discrete, spherical with relatively smooth surface, and with good flow properties. The drug entrapment efficiency obtained in the range 70.4% to 95.2%.Among different formulations, the fabricated microspheres of batch F3 had shown the optimum percent drug encapsulation of microspheres and the sustained release of the saxagliptin for about 9 h. In vitro study showed that drug release slowly increases as the pH of the medium is increased. Release pattern of saxagliptin from microspheres of batch F3 followed Higuchi model and zero-order release kinetic model. The value of ‘n’ was found to be 0.867. The data obtained thus suggest that a microparticulate system can be successfully designed for sustained delivery of saxagliptin and to improve dosage form characteristics for easy formulation.

Application of sustained release microsphere in hypoparathyroidism after thyroid surgery

Hypoparathyroidism (HypoPT) is one of the most common complications after thyroid surgery. The parathyroid hormone-controlled delivery system is one of the most significant therapies for hypothyroidism after thyroid and parathyroid surgery. The character of biodegradability and the slow release of PTH of the Sustained release microspheres were widely concerned. The authors present the research progress in sustained release microspheres loaded with PTH from the character, material, fabrication and application.

Evaluation of glibenclamide microspheres for sustained release

Context: Sustained release drug delivery systems are more preferred than the conventional drug delivery systems due to its enhanced bioavailability and patient compliance. Earlier studies reported on glibenclamide (GBCM) were not clear and hence, the step has been taken to explore the sustained release drug delivery system of GBCM. Aims: To evaluate the sustained release microspheres obtained of GBCM. Methods: Microspheres were prepared by ionic gelation method using the polymers like Eudragit RS 100 and xanthan gum. Polymers can sustain the drug release from microspheres. The prepared microspheres were subjected to micromeritic studies like Carr’s index, Hausner’s ratio and angle of repose. Results: Micromeritic studies confirmed that the microspheres possessing acceptable flow properties. It was observed from the in vitro release studies, formulations F8 and F9 showed sustained drug release for desired time of 12 h and when compared to F9, formulation F8 showed maximum drug release for 12 h. Conclusions: Results confirmed the formulation F8 consist of the polymers such as Eudragit RS 100 about 150 mg and xanthan gum about 100 mg showed desired sustained release of 12 h with 96.07% and kinetic studies confirmed that the release from microspheres followed non-Fickian diffusion mechanism. Due to its sustained release property, it could enhance the bioavailability of drug thereby improves the patient compliance and expect better treatment than conventional dosage forms.

Development of ligustrazine hydrochloride carboxymethyl chitosan and collagen microspheres: Formulation optimization, characterization, and vitro release

ABSTRACTThis study investigates the preparation of ligustrazine hydrochloride carboxymethyl chitosan and collagen microspheres. This experiment investigates effects of the ratio of carboxymethyl chitosan and collagen blend, water to oil ratio, stirring speed, and other factors on the microsphere properties. The experiment had the following conditions: a 1:2 proportion of carboxymethyl chitosan and collagen, a 1:2 proportion of drugs and materials, a 5:1 proportion of oil phase and water phase, 0.5% of span80, a 600r/min stirring speed, 3 ml of a cross-linking agent, 3 h of cross-linking curing, 1.25 ± 0.05 mm diameter LTH microcapsules, a 54.08% envelop rate, and a 14.16% carrier rate. The microspheres release rate reached 66% within 1 h, then steadily released within 5 h in vitro. The experimental results showed that the ligustrazine hydrochloride microsphere production process was stable and exhibited a good release effect compared with other ligustrazine hydrochloride tablets and pills.

Characterizing release mechanisms of leuprolide acetate-loaded PLGA microspheres for IVIVC development I: In vitro evaluation

Release testing of parental controlled release microspheres is an essential step in controlling quality and predicting the duration of efficacy. In the first of a two-part study, we examined the effect of various incubation media on release from leuprolide-loaded PLGA microspheres to understand the influence of external pH, plasticization, and buffer type on mechanism of accelerated release. PLGA 50/50 microspheres encapsulating ~5% w/w leuprolide were prepared by the double emulsion-solvent evaporation method with or without gelatin or by the self-healing encapsulation method. The microspheres were incubated at 37°C up to 56days in various media: pH5.5, 6.5, and 7.4 phosphate buffered-saline (PBS) containing 0.02% Tween 80; pH7.4 PBS containing 1.0% triethyl citrate (PBStc); and pH7.4 HEPES buffered-saline containing 0.02% Tween 80 (all media contained 0.02% sodium azide). The recovered release media and microspheres were examined for released drug, polymer molecular weight (Mw), water uptake, mass loss, and BODIPY (green-fluorescent dye) diffusion coefficient in PLGA. After the initial burst release, release of leuprolide from acid-capped PLGA microspheres appeared to be controlled initially by erosion and then by a second mechanism after day 21, which likely consists of a combination of peptide desorption and/or water-mediated breakage of pore connections. PBStc and acidic buffers accelerated degradation of PLGA and pore-network development and increased BODIPY diffusion coefficient, resulting in faster release. Release of leuprolide from the end-capped PLGA showed similar trends as found with acid capped PLGA but with a longer lag time before release. These data provide a baseline mechanistic signature of in vitro release of leuprolide for future comparison with corresponding in vivo performance, and in turn could lead to future development of rational in vitro-in vivo correlations.

Validation of a cage implant system for assessing invivo performance of long-acting release microspheres.

Here we describe development of a silicone rubber/stainless steel mesh cage implant system, much like that used to assess biocompatibility of biomaterials [1], for easy removal of injectable polymer microspheres invivo. The sterile cage has a type 316 stainless steel mesh size (38μm) large enough for cell penetration and free fluid flow invivo but small enough for microsphere retention, and a silicone rubber shell for injection of the microspheres. Two model drugs, the poorly soluble steroid, triamcinolone acetonide, and the highly water-soluble luteinizing hormone-releasing hormone (LHRH) peptide superagonist, leuprolide, were encapsulated in PLGA microspheres large enough (63-90μm) to be restrained by the cage implant invivo. The invitro release from both formulations was followed by ultra-performance liquid chromatography (UPLC) with and without the cage in a standard release media, PBS pH 7.4+0.02% Tween 80+0.05% sodium azide, at 37°C. Pharmacokinetics (PK) in rats was assessed after SC injection or SC in-cage implantation of microspheres with plasma analysis by LC-MS/MS or EIA. Tr-A and leuprolide invitro release was largely unaffected after the initial burst irrespective of the cage or test tube incubation vessel and release was much slower than observed invivo for both drugs. Moreover, Tr-A and leuprolide pharmacokinetics with and without the cage were highly similar during the 2-3 week release duration before a significant inflammatory response was caused by the cage implant. Hence, the PK-validated cage implant provides a simple means to recover and evaluate the microsphere drug carriers invivo during a time window of at least a few weeks in order to characterize the polymer microsphere release and erosion behavior invivo. This approach may facilitate development of mechanism-based invitro/invivo correlations and enable development of more accurate and useful invitro release tests.

Formulation and Optimization of Carbamazepine Microspheres by 2 Factor 2 Level Central Composite Design

The present investigation was designed to prepare controlled release microspheres of carbamazepine using two polymers of different solubility and permeability characteristics, Ethocel standard 45 premium and Eudragit RL 100. The drug release profile was optimized with the aid of design of experiments (DoE). Microspheres of combined polymers were designed according to 22 factorial central composite design (CCD), taking drug loading and polymeric ratio as the independent variables. Total thirteen batches were prepared. The dependent variables were percentage of drug released in 3 hours and 6 hours and mean dissolution time (MDT). The regression parameters of the developed model and graphical interpretation for each response with statistical significance were calculated by using Minitab 17. The relationship between the experimental variables and responses were evaluated by generating response surface plots. Increased amount of Eudragit RL 100 had impact on surface morphology of prepared microspheres. It produced larger holes on the surface due to its higher permeability characteristics. Polynomial mathematical models generated for various response variables using multiple linear regression analysis, were found to be statistically significant (p &lt; 0.05). One optimum formulation (O1) was selected based on USP specification and the second optimum formulation (O2) was selected for the maximization of MDT (hours). Batch O1 showed 22.85 % and 48.78 % drug release after 3 and 6 hours, respectively which were found to be in close agreement with those predicted by the mathematical model. Another optimum formulation, batch O2 showed MDT as 160.61 hours.Bangladesh Pharmaceutical Journal 19(2): 152-160, 2016

Formulation and In vitro Evaluation of Eudragit RL 100 Loaded Fexofenadine HCl Microspheres

The present study deals with the formulation and evaluation of Fexofenadine hydrochloride (HCl) loaded sustained release microspheres by emulsion solvent evaporation method with Eudragit RL 100. The effects of percent drug loading on drug encapsulation efficiency, drug content and drug release rate were assessed. In vitro dissolution study was performed spectrophotometrically according to USP paddle method using phosphate buffer (pH 6.8) for 10 hours. The release rate of Fexofenadine HCl from the microspheres was significantly increased with the increase of drug loading. The drug release patterns were simulated in different kinetic orders such as zero order release kinetics, first order release kinetics, Higuchi release kinetics, Korsmeyer-Peppas release kinetics and Hixson-Crowell release kinetics to assess the release mechanism and Higuchi release kinetics was found to be the predominant release mechanism. Morphological changes due to different drug loading were assessed by scanning electron microscopic (SEM) technique. Differential scanning calorimetry and fourier transform infra-red (FT-IR) spectroscopy was performed to evaluate compatibility of drug with the polymer. A statistically significant variation indrug encapsulation efficiency and release rate was observed for variation in drug loading.Bangladesh Pharmaceutical Journal 19(1): 58-67, 2016

Design, characterization and in vitro evaluation of HPMC K100 M CR loaded Fexofenadine HCl microspheres.

The aim of the current study was to formulate Fexofenadine hydrochloride loaded sustained release microspheres using HPMC K100 M CR, a release retardant hydrophilic polymer by solvent evaporation method. The effect of different drug loading on drug content, drug encapsulation efficiency and release of drug was monitored. The studies on in vitro release mechanism were performed using USP paddle method with 900 ml of phosphate buffer (pH 6.8) for 10 h at 100 rpm. The mechanism of the drug release was determined by fitting in vitro release data to various release kinetic models such as the zero order, first order, Higuchi, Hixson Crowell and Korsemeyer–Peppas model and finding R2 values for the release profile corresponding to each model. The results confirm that the release rate of the drug from the microspheres is highly affected by the drug to polymer ratio. The study finds that Higuchi release kinetics, Korsmeyer–Peppas release kinetics and Hixson–Crowell release kinetics were the major release mechanism. The release mechanism was found to be non-Fickian with increase of polymer content. Scanning electron microscopic technique was performed to obtain the morphological changes due to different drug loading. Differential scanning calorimetry and Fourier transform infra-red spectroscopy was performed to determine any interaction of drug with the polymer. A statistically significant variation in release rate was observed for variation in the amount of HPMC K100 M CR. In the present study, a series of sustained release formulations of Fexofenadine hydrochloride were developed with different drug loading so that these formulations could further be evaluated from the in vivo studies. The formulations were found to be stable and reproducible.

Formulation and Evaluation of Mucoadhesive Acarbose Microspheres

The purpose of the present investigation was the formulation and characterization of mucoadhesive sustained release microsphere of antidibetic drug Acarbose that would adhere in mucosa and release continuously to provide long term effect. There was various formulations of Acarbose were prepared by solvent evaporation technique using hydroxypropyl methylcellulose (HPMC), Sodium Alginate, Carbopol, Xanthan gum, Guar gum as a polymer. The prepared mucoadhesive microspheres were evaluated for particle size, surface morphology, drug entrapment efficiency, Drug content, buoyancy percentage and In-vitro drug release, In-vitro adhesion test and stability studies. The particle was found to be discrete and spherical with the average particle size in the range of 105.5 to 413.5μm. As the concentration of polymers increases it affects the various evaluation parameters like particle size, in-vitro drug release and In-vitro adhesion. The floating microspheres of optimized formulation exhibited the prolonged release of 85.8% in continuous manner up to 12 hrs. It is concluded that the optimized formulation of Acarbose mucoadhesive microspheres can be selected for sustained drug delivery system for improved bioavailability.

A novel study on the mechanisms of drug release in PLGA-mPEG microspheres with fluorescent drug

The purpose of this research was to proof the microspheres release mechanism by a novel method-detecting and comparing the drugs fluorescent changes on the microspheres surface. Fluorescein sodium (FS, 0.4 kDa) and fluorescein isothiocyanate-bovine serum albumin (FITC-BSA, 66.8 kDa) were employed as model drugs. FS and FITC-BSA were encapsulated into PLGA-mPEG microspheres through double emulsion evaporation method, and the drug-loaded microspheres in vitro degradation and release behaviors were evaluated by scanning electron microscope, gel permeation chromatography, confocal laser scanning microscopy (CLSM), BCA assay kit, and UV–vis spectrophotometry. FS-loaded microspheres revealed a severe initial burst release, followed by a sustained release, and we could observe a bright fluorescent on the microspheres surface during the early release period under the CLSM. The bright fluorescent gradually faded out in the later period as only 1~2% FS was remained after 14 days release. FITC-BSA-loaded microspheres revealed a typical tri-phase release profile, and we observed a weak fluorescent on the microspheres surface after the initial burst release, and the fluorescent came bright again after an obvious erosion appeared on the microspheres surface. In the later release stage, the fluorescent gradually faded out as the fast release of FITC-BSA.

Formulation and Characterization of Sustained Release Microspheres of Lornoxicam Using Gelatin with HPMCAS Coating

SummarySustained release polymeric microspheres of lornoxicam are prepared by using calcium chloride gelatin followed by amphiphilic HPMCAS (Hydroxypropyl Methylcellulose Acetate Succinate H grade) polymer by solvent evaporation method. Polyvinyl alcohol (PVA) is used as an emulsifier which was found to improve shape whereas HPMCAS increased surface smoothness of microspheres. In vitro dissolution studies in acidic and neutral pH showed sustained release profile for all formulations. Microspheres were characterized by using advanced analytical instruments like SEM, XRD, DSC, FT‐IR, Raman spectroscopy etc. Microspheres are evaluated for its swelling index, shape and entrapment efficiency. The prepared microspheres found to be stable and release controlled which consequently sustained the drug effect for longer time.