Taste Masking by Spray-Drying Technique

The purpose of this research was to develop the taste-masked microspheres of intensely bitter drug ondansetron hydrochloride (OSH) by spray-drying technique. The bitter taste threshold value of OSH was determined. Three different polymers viz. Chitosan, Methocel E15 LV, and Eudragit E100 were used for microsphere formation, and the effect of different polymers and drug–polymer ratios on the taste masking and release properties of microspheres was investigated. The microspheres were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, Drug loading, in vitro bitter taste evaluation, and drug-release properties. The taste masking was absent in methocel microspheres at all the drug–polymer ratios. The Eudragit microspheres depicted taste masking at 1:2 drug–polymer ratio whereas with Chitosan microspheres the taste masking was achieved at 1:1 drug–polymer ratio. The drug release was about 96.85% for eudragit microspheres and 40.07% for Chitosan microspheres in 15 min.     

Preparation and in vitro evaluation of xanthan gum facilitated superabsorbent polymeric microspheres

Interpenetrating polymer network (IPN) hydrogel microspheres of xanthan gum (XG) based superabsorbent polymer (SAP) and poly(vinyl alcohol) (PVA) were prepared by water-in-oil (w/o) emulsion crosslinking method for sustained release of ciprofloxacin hydrochloride (CIPRO). The microspheres were prepared with various ratios of hydrolyzed SAP to PVA and extent of crosslinking density. The prepared microspheres with loose and rigid surfaces were evidenced by scanning electron microscope (SEM). Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the IPN formation. Differential scanning calorimetry (DSC) study was performed to understand the dispersion nature of drug after encapsulation. The in vitro drug release study was extensively evaluated depending on the process variables in both acidic and alkaline media. All the formulations exhibited satisfactory physicochemical and in vitro release characteristics. Release data indicated a non-Fickian trend of drug release from the formulations. Based on the results, this study suggest that CIPRO loaded IPN microspheres were suitable for sustained release application.     

Interpenetrating polymer network (IPN) hydrogel microspheres for oral controlled release application

Interpenetrating polymer network (IPN) hydrogel microspheres of sodium carboxymethyl cellulose (NaCMC) and poly(vinyl alcohol) (PVA) were prepared by water-in-oil (w/o) emulsion crosslinking method for oral controlled release delivery of a non-steroidal anti-inflammatory drug, diclofenac sodium (DS). The microspheres were prepared with various ratios of NaCMC to PVA, % drug loading and extent of crosslinking density at a fixed polymer weight. The prepared microspheres with loose and rigid surfaces were evidenced by scanning electron microscope (SEM). Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the IPN formation. Differential scanning calorimetry (DSC) study was performed to understand the dispersion nature of drug after encapsulation. The in vitro drug release study was extensively evaluated depending on the process variables in both acid and alkaline media. All the formulations exhibited satisfactory physicochemical and in vitro release characteristics. Release data indicated a non-Fickian trend of drug release from the formulations. Based on the results of this study suggest that DS loaded IPN microspheres were suitable for oral controlled release application.     

Influence of aluminum tristearate and sucrose stearate as the dispersing agents on physical properties and release characteristics of Eudragit RS microspheres

The purpose of this research was to investigate the effects of different concentrations of polymer and sucrose stearate, aluminum tristearate as dispersing agents on microsphere properties and performance. The yield values of microspheres were over the 78%, and the encapsulation efficiencies were found to be ∼735. Particle sizes of microspheres prepared with aluminum tristearate were between 76 and 448 μm, while that of the microspheres containing sucrose stearate were between 521 and 2000 μm. Morphological and physicochemical properties of microspheres were investigated by scanning electron micrography and differential scanning calorimetry (DSC). DSC analysis indicated that verapamil hydrochloride formed a solid solution with acrylic polymers. In vitro release studies were performed using the flow-through cell method. While ∼80% of drug was released from the microspheres containing aluminum tristearate in 480 minutes, the same amount of drug was released from microspheres containing sucrose stearate in only 60 minutes. Chemical structures and concentrations of the dispersing agents were clearly effective on the physical properties of microspheres and their drug-release characteristics. Published: February 24, 2006     

Preparation and Evaluation of Taste Masked Famotidine Formulation Using Drug/β-cyclodextrin/Polymer Ternary Complexation Approach

The main aim of the present study was to evaluate potential of ternary complexation (comprising of drug, cyclodextrin and polymer) as an approach for taste masking. For this purpose famotidine with property of bitter taste was selected as a model drug. Improvement in taste masking capability of cyclodextrin towards famotidine was evaluated by formulating a ternary complex including hydrophilic polymer hydroxyl propyl methyl cellulose (HPMC 5 cps) as the third component. Phase solubility analysis at 25 °C was carried out for both the binary systems (viz. drug–cyclodextrin and drug–polymer) and the ternary system (drug–cyclodextrin–polymer). Ternary complex was prepared using solution method and was further characterized using XRD, DSC, FT-IR and microscopic studies. In vitro dissolution study was carried out to see the effect of ternary complexation on drug release. Taste perception study was carried out on human volunteers to evaluate the taste masking ability of ternary complexation. Results obtained from phase solubility analysis showed that the combined use of polymer and cyclodextrin effectively increased the stability constant of the complex [from 538 M⁻¹ for binary system to 15,096 M⁻¹ for ternary system]. Ternary system showed effective taste masking as compared to binary complex and at the same time showed no limiting effect on the drug release (D.E_15min = 90%). The effective taste masking was attributed to the enhanced complexation of famotidine in ternary system compared to binary system and the same was confirmed from the characterization studies. In conclusion, the study confirmed that ternary complexation can be utilized as an alternative approach for effective taste masking.     

Novel interpenetrating polymer network microspheres of chitosan and methylcellulose for controlled release of theophylline

Interpenetrating polymer network (IPN) microspheres of chitosan (CS) and methylcellulose (MC) were prepared by emulsion-crosslinking in the presence of glutaraldehyde (GA) as a crosslinker. Theophylline (THP), an antiasthmatic drug was encapsulated into IPN microspheres under varying ratios of MC and CS, % drug loading and amount of GA added. IPNs have shown better mechanical properties than pure CS. Cross-link density of the matrices was significantly affected by the amount of GA and MC. Microspheres were characterized by Fourier transform infrared (FTIR) spectroscopy to assess the formation of IPN structure and to confirm the absence of chemical interactions between drug, polymer and crosslinking agent. Particle size was measured by laser light scattering technique. Microspheres with the average particle sizes ranging from 119 to 318 μm were produced. Differential scanning calorimetry (DSC) and X-ray diffraction (X-RD) studies were performed to understand the crystalline nature of drug after encapsulation into IPN microspheres. Theophylline encapsulation of up to 82% was achieved as measured by UV spectrometer. Equilibrium swelling was performed in distilled water. In vitro release studies were performed in both 0.1 N HCl and pH 7.4 buffer solutions. These data indicated a dependence of drug release on the extent of crosslinking and amount of MC added during the preparation of microspheres. The release was extended up to 12 h and release rates were fitted to an empirical equation to compute the diffusional parameters, which indicated a slight deviation from the Fickian trend for the release of theophylline.     

Novel composite blend microbeads of sodium alginate coated with chitosan for controlled release of amoxicillin

Composite blend microbeads of sodium alginate (NaAlg) with sodium carboxymethyl cellulose (NaCMC) containing magnesium aluminum silicate (MAS) particles and enteric coated with chitosan have been prepared to achieve controlled release (CR) of amoxicillin in stomach environment. The composite beads have been characterized by X-ray diffraction (XRD) to study drug distribution, DSC for understanding thermal stability and Fourier transform infrared (FTIR) spectroscopy to investigate chemical interactions as well as to assess the structure of the drug-loaded formulations. Surface morphology of the beads was investigated by scanning electron microscopy (SEM). The size distribution of beads loaded with drug as studied by particle size analyzer was in the range of 745-889 μm. The beads exhibited quite widely varying encapsulation efficiencies from 52 to 92%. Equilibrium swelling of the beads measured in water and in vitro release of amoxicillin in pH 1.2 medium suggests that drug release depends on polymer blend composition, concentration of MAS and extent of enteric coating.     

Effect of Drying Methods on Swelling,Erosion and Drug Release from Chitosan–Naproxen Sodium Complexes

The purpose of this research was to explore theapplication of ionic interactions between naproxen sodium (NS) and chitosan (CH) in complexes (NSC) prepared by tray drying (TD) and spray drying (SD) methods. Drug–polymer ratio (1:1) in the NSC was optimized on the basis of dialysis studies. The particulate systems of NSC were prepared by tray drying (TD) and spray drying (SD) methods. Release retarding polymers were added to the NSC and to the physical mixtures containing NS–CH and their effects on water uptake, matrix erosion and drug release at different pH were compared. Spray dried complexes (SDC) were spherical, free flowing, light and fine amorphous particles in contrast to the crystalline, hard, tenacious, irregularly shaped, denser tray dried complexes (TDC) with poor flowability. Differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and Fourier transform infrared (FTIR) patterns confirm the conversion of crystalline to high energy amorphous phase suitable for ionic interactions in NSC. Presence of release retarding polymers, kappa carrageenan and hydroxypropylmethylcellulose (HPMC) in the NSC compacts retarded the drug release and improved the matrix integrity. Carrageenan matrices exhibited more retardation than HPMC tablets. FTIR patterns, erosion, swelling and drug release from matrices support ionic interactions between NS and CH in NSC. The reasons for retarded drug release from the chitosan matrices at acidic pH include poor solubility of drug at acidic pH, formation of a rate limiting polymer gel barrier along the periphery of matrices and the ionic interactions between oppositely charged moieties.     

Microparticulate Based Topical Delivery System of Clobetasol Propionate

Psoriasis is a chronic, autoimmune skin disease affecting approximately 2% of the world's population. Clobetasol propionate which is a superpotent topical corticosteroid is widely used for topical treatment of psoriasis. Conventional dosage forms like creams and ointments are commonly prefered for the therapy. The purpose of this study was to develop a new topical delivery system in order to provide the prolonged release of clobetasol propionate and to reduce systemic absorption and side effects of the drug. Clobetasol propionate loaded-poly(D,L-lactic-co-glycolic acid) (PLGA) microspheres were prepared by oil-in-water emulsion–solvent evaporation technique. Particle size analysis, morphological characterization, DSC and XRD analyses and in vitro drug release studies were performed on the microparticle formulations. Emulgel formulations were prepared as an alternative for topical delivery of clobetasol propionate. In vitro drug release studies were carried out from the emulgel formulations containing pure drug and drug-loaded microspheres. In addition, the same studies were performed to determine the drug release from the commercial cream product of clobetasol propionate. The release of clobetasol propionate from the emulgel formulations was significantly higher than the commercial product. In addition, the encapsulation of clobetasol propionate in the PLGA microspheres significantly delayed the drug release from the emulgel formulation. As a result, the decrease in the side effects of clobetasol propionate by the formulation containing PLGA microspheres is expected.     

Investigation on Processing Variables for the Preparation of Fluconazole-Loaded Ethyl Cellulose Microspheres by Modified Multiple Emulsion Technique

Fluconazole-loaded ethyl cellulose microspheres were prepared by alginate facilitated (water-in-oil)-in-water emulsion technology and the effects of various processing variables on the properties of microspheres were investigated. Scanning electron microscopy revealed spherical nature and smooth surface morphology of the microspheres except those prepared at higher concentration of emulsifiers and higher stirring speeds. The size of microspheres varied between 228 and 592 μm, and as high as 80% drug entrapment efficiency was obtained depending upon the processing variables. When compared up to 2 h, the drug release in pH 1.2 HCl solution was slower than in pH 7.4 phosphate buffer saline solution. However, this trend was reversed at high shear conditions. The microspheres provided extended drug release in alkaline dissolution medium and the drug release was found to be controlled by Fickian-diffusion mechanism. However, the mechanism shifted to anomalous diffusion at high shear rates and emulsifier concentrations. The aging of microspheres did not influence the drug release kinetics. However, the physical interaction between drug and excipients affected the drug dissolution behaviors. X-ray diffractometry (X-RD) and differential scanning calorimetry (DSC) analysis revealed amorphous nature of drug in the microspheres. Fourier transform infrared (FTIR) spectroscopy indicated stable character of fluconazole in the microspheres. The stability testing data also supported the stable nature of fluconazole in the microspheres. The fluconazole extracted from 80% drug-loaded formulation showed good in vitro antifungal activity against Candida albicans. Thus, proper control of the processing variables involved in this modified multiple emulsion technology could allow effective incorporation of slightly water soluble drugs into ethyl cellulose microspheres without affecting drug stability.     

Oxycellulose Beads with Drug Exhibiting pH-Dependent Solubility

The aim of this study was to develop novel hydrogel-based beads and characterize their potential to deliver and release a drug exhibiting pH-dependent solubility into distal parts of gastrointestinal (GI) tract. Oxycellulose beads containing diclofenac sodium as a model drug were prepared by the ionotropic external gelation technique using calcium chloride solution as the cross-linking medium. Resulting beads were characterized in terms of particle shape and size, encapsulation efficacy, swelling ability and in vitro drug release. Also, potential drug–polymer interactions were evaluated using Fourier transform infrared spectroscopy. The particle size was found to be 0.92–0.96 mm for inactive (oxycellulose only) and 1.47–1.60 mm for active (oxycellulose–diclofenac sodium) beads, respectively. In all cases, the sphericity factor was between 0.70 and 0.81 with higher values observed for samples containing higher polymer and drug concentrations. The swelling of inactive beads was found to be strongly influenced by the pH and composition (i.e. Na⁺ concentration) of the selected media (simulated gastric fluid vs. phosphate buffer pH 6.8). The encapsulation efficiency of the prepared particles ranged from 58% to 65%. Results of dissolution tests showed that the drug loading inside of the particles influenced the rate of its release. In general, prepared particles were able to release the drug within 12–16 h after a lag time of 4 h. Fickian diffusion was found as the predominant drug release mechanism. Thus, this novel particulate system showed a good potential to deliver drugs specifically to the distal parts of the human GI tract.     

Anhydride Prodrug of Ibuprofen and Acrylic Polymers

The objective of this study was to synthesize anhydride prodrugs for carboxylic-acid-bearing agents such as non-steroidal anti-inflammatory drugs, shield the carboxylic acid group from irritative effects, and obtain sustained release patterns. Ibuprofen was used as a representative drug for anhydride derivatization. Conjugates of ibuprofen with carboxylic acid moieties of different acrylic polymers were prepared by dehydration reaction using acetic anhydride. Products were characterized by infrared spectroscopy, nuclear magnetic resonance, and scanning electron microscopy followed by preparation of microspheres with different sizes from the conjugate Eudragit® L-100-ibuprofen. The drug release was monitored by high-performance liquid chromatography. Ibuprofen was bound to the polymers via an anhydride bond in high reaction yields (75–95%) with drug loading of up to 30% (w/w). These anhydride derivatives hydrolyzed and release the drug at different periods ranging from 1 to 5 days, depending on the hydrophobicity and the cross-linking of the conjugates. The release of drug from the microspheres was correlated to their size and ranged from 2 to almost 8 days. This study demonstrates the promise of anhydride prodrug for extending drug action while shielding the carboxylic acid group.     

Synthesis and characterization of chitosan-based pH-sensitive semi-interpenetrating network microspheres for controlled release of diclofenac sodium

pH-Sensitive semi-interpenetrating networks (IPNs) based on chitosan (Cs) and acrylamide-grafted hydroxyethylcellulose (AAm-g-HEC) were prepared in the form of microspheres (MPs) by emulsion-crosslinking technique using glutaraldehyde (GA) as a crosslinker. Diclofenac sodium (DS) drug was successfully encapsulated into IPN microspheres by varying the ratio of Cs and AAm-g-HEC, % drug loading, and amount of GA. DS encapsulation of up to 83% was obtained as measured by UV spectroscopy. MPs with average particle sizes in the range of 188-310 μm were obtained. MPs were characterized by Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and Differential scanning calorimetry (DSC). Diffusion coefficients (D) of water transport through the microspheres were determined using an empirical equation. In vitro release of DS from these matrices has been investigated in pH 1.2 and 7.4 media.     

Cellulose-Based Matrix Microspheres of Prednisolone Inclusion Complex: Preparation and Characterization

The purpose of the present investigation was to encapsulate pure prednisolone (PRD) and PRD–hydroxypropyl-β-cyclodextrin (HPβCD) complex in cellulose-based matrix microspheres. The system simultaneously exploits complexation technique to enhance the solubility of low-solubility drug (pure PRD) and subsequent modulation of drug release from microspheres (MIC) at a predetermined time. The microspheres of various compositions were prepared by an oil-in-oil emulsion–solvent evaporation method. The effect of complexation and presence of cellulose polymers on entrapment efficiency, particle size, and drug release had been investigated. The solid-state characterization was performed by Fourier transform infrared spectroscopy, thermogravimetry, differential scanning calorimetry, and powder X-ray diffractometry. The morphology of MIC was examined by scanning electron microscopy. The in vitro drug release profiles from these microspheres showed the desired biphasic release behavior. After enhancing the solubility of prednisolone by inclusion into HPβCD, the drug release was easily modified in the microsphere formulation. It was also demonstrated that the CDs in these microspheres were able to modulate several properties such as morphology, drug loading, and release properties. The release kinetics of prednisolone from microspheres followed quasi-Fickian and first-order release mechanisms. In addition to this, the f ₂-metric technique was used to check the equivalency of dissolution profiles of the optimized formulation before and after stability studies, and it was found to be similar. A good outcome, matrix microspheres (coded as MIC5) containing PRD–HPβCD complex, showed sustained release of drug (95.81%) over a period of 24 h.     

Preparation and characterization of glutaraldehyde cross-linked O-carboxymethylchitosan microspheres for controlled delivery of pazufloxacin mesilate

O-carboxymethylchitosan (OCMC) microspheres containing an antibiotic drug pazufloxacin mesilate (PM) have been successfully prepared by emulsion cross-linking using glutaraldehyde (GA). Various manufacturing parameters, including amount of cross-linking agent and OCMC:PM ratios were altered to optimize process variables during the microspheres production. The structure and morphology were characterized by Fourier transform infrared (FT-IR), wide-angle X-ray diffraction (WXRD) and scanning electron microscopy (SEM). The swelling and releasing behaviors of the microspheres at pH 1.2 and 7.4 media were investigated. The results revealed that the microspheres had a spherical, rough morphology and with a narrow size distribution. The degree of swelling of microspheres at pH 7.4 media was higher than that at pH 1.2 media. The microspheres proved to be successful in prolonging drug release. The release of PM was found to depend upon the extent of matrix cross-linking and drug loading. The release profiles of PM from OCMC microspheres were found to be biphasic with a burst release followed by a gradual release phase, and followed the Higuchi matrix model.     

Preparation of aspirin and probucol in combination loaded chitosan nanoparticles and in vitro release study

We design and develop chitosan nanoparticles which load two different drugs simultaneously. Aspirin (acetylsalicylic acid, ASA), a hydrophilic drug and probucol (PRO), a hydrophobic drug, are chosen as typical drugs, which are widely used to treat restenosis. The drug loaded chitosan nanoparticles are prepared by gelation of chitosan with tripolyphosphate (TPP) by ionic cross-linking. The physicochemical properties of nanoparticles are investigated by FTIR, transmission electron microscope (TEM), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The images show that these particles are spherical in shape with ASA being in the amorphous phase, while PRO is crystalline. The properties of chitosan nanoparticles such as encapsulation capacity and controlled release behaviors of ASA and PRO are evaluated. Experimental results indicate that the loading capacity (LC), encapsulation efficiency (EE) and ASA and PRO release behaviors are affected by several factors including pH, concentration of TPP, chitosan molecular weight (MW) and ASA initial concentration as well as PRO. In vitro release shows that the nanoparticles provide a continuous release. Entrapped ASA is released for more than 24 h and PRO lasts longer for 120 h.     

Synthesis and characterization of semi-interpenetrating polymer network microspheres of acrylamide grafted dextran and chitosan for controlled release of acyclovir

Semi-interpenetrating polymer network (IPN) microspheres of acrylamide grafted on dextran (AAm-g-Dex) and chitosan (CS) were prepared by emulsion-crosslinking method using glutaraldehyde (GA) as a crosslinker. The grafting efficiency was found to be 94%. Acyclovir, an antiviral drug with limited water solubility, was successfully encapsulated into IPN microspheres by varying the ratio of AAm-g-Dex and CS, % drug loading and amount of GA. Microspheres were characterized by FT-IR spectroscopy to assess the formation of IPN structure and to confirm the absence of chemical interactions between drug, polymer and crosslinking agent. Particle size was measured using laser light scattering technique. Microspheres with average particle sizes in the range of 265–388 μm were obtained. Differential scanning calorimetry (DSC) and X-ray diffraction (X-RD) studies were performed to understand the crystalline nature of drug after encapsulation into IPN microspheres. Acyclovir encapsulation of up to 79.6% was achieved as measured by UV spectroscopy. Both equilibrium and dynamic swelling studies were performed in 0.1 N HCl. Diffusion coefficients (D) and diffusional exponents (n) for water transport were determined using an empirical equation. In vitro release studies indicated the dependence of drug release rates on both the extent of crosslinking and amount of AAm-g-Dex used in preparing microspheres; the slow release was extended up to 12 h. The release rates were fitted to an empirical equation to compute the diffusional exponent (n), which indicated non-Fickian trend for the release of acyclovir.     

Chitosan–Chondroitin Sulfate Based Matrix Tablets for Colon Specific Delivery of Indomethacin

The different approaches for targeting orally administered drugs to the colon include coating with pH-dependent polymers, design of time-release dosage forms, and the utilization of carriers that are degraded exclusively by colonic bacteria. The aim of the present study was to develop a single unit, site-specific drug formulation allowing targeted drug release in the colon. Matrix tablets were prepared by wet granulation using cross-linked chitosan (ChI) and chondroitin sulfate (ChS) polysaccharides as binder and carrier. ChS was used to form polyelectrolyte complexes (PEC) with ChI, and its potential as a colon-targeted drug carrier was investigated. Indomethacin was used as a model drug. The ChI and ChS PEC was characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and powder X-ray diffraction studies (XRD). The matrix tablets were tested in vitro for their suitability as colon-specific drug delivery systems. FTIR demonstrated that the PEC forms through an electrostatic interaction between the protonated amine (NH₃⁺) group of ChI with the free carboxylate (COO⁻) group and sulfate (SO₄²⁻) group of ChS. DSC and XRD indicated that the PEC has different thermal characteristics from ChI or ChS. The dissolution data demonstrates that the dissolution rate of the tablet is dependent upon the concentration of polysaccharide used as binder and matrix and time of cross-linking. The study confirmed that selective delivery of indomethacin to the colon can be achieved using cross-linked ChI and ChS polysaccharides.     

Synthesis and Characterization of PLGA Shell Microcapsules Containing Aqueous Cores Prepared by Internal Phase Separation

The preparation of microcapsules consisting of poly(d,l-lactide-co-glycolide) (PLGA) polymer shell and aqueous core is a clear challenge and hence has been rarely addressed in literature. Herein, aqueous core-PLGA shell microcapsules have been prepared by internal phase separation from acetone-water in oil emulsion. The resulting microcapsules exhibited mean particle size of 1.1?±?0.39 μm (PDI?=?0.35) with spherical surface morphology and internal poly-nuclear core morphology as indicated by scanning electron microscopy (SEM). The incorporation of water molecules into PLGA microcapsules was confirmed by differential scanning calorimetry (DSC). Aqueous core-PLGA shell microcapsules and the corresponding conventional PLGA microspheres were prepared and loaded with risedronate sodium as a model drug. Interestingly, aqueous core-PLGA shell microcapsules illustrated 2.5-fold increase in drug encapsulation in comparison to the classical PLGA microspheres (i.e., 31.6 vs. 12.7%), while exhibiting sustained release behavior following diffusion-controlled Higuchi model. The reported method could be extrapolated to encapsulate other water soluble drugs and hydrophilic macromolecules into PLGA microcapsules, which should overcome various drawbacks correlated with conventional PLGA microspheres in terms of drug loading and release.     

Albumin microspheres as carriers for the antiarthritic drug celecoxib

The present study investigates the preparation of celecoxib-loaded albumin microspheres and the biodistribution of technetium-99m (^99mTc)-labeled celecoxib as well as its microspheres after intravenous administration. Microspheres were prepared using a natural polymer BSA using emulsification chemical cross-linking method. The prepared microspheres were characterized for entrapment efficiency, particle size, and in vitro drug release. Surface morphology was studied by scanning electron microscopy. Biodistribution studies were performed by radiolabeling celecoxib (CS) and its microspheres (CMS) using^99mTc and injecting arthritic rats intravenously. The geometric mean diameter of the microspheres was found to be 5.46 μm. In vitro release studies indicated that the microspheres sustained the release of the drug for }6 days. Radioactivity measured in different organs after intravenous administration of celecoxib solution showed a significant amount of radioactivity in the liver and spleen. In case of celecoxib-loaded microspheres, a significant amount of radioactivity accumulated in the lungs. No significant difference (P>.1) in the radioactivity was observed between the inflamed joint and the noninflamed joint following intravenous injection of^99mTc-CS. However, in case of the microspheres (CMS), the radioactivity present in the inflamed joint was 2.5-fold higher than in the noninflamed joint. The blood kinetic studies revealed that celecoxib-loaded albumin microspheres exhibited prolonged circulation than the celecoxib solution.