Formulation and in vitro evaluation of prolonged release floating microspheres of atenolol using multicompartment dissolution apparatus

The aim of the present work was to prepare floating microspheres of atenolol as prolonged release multiparticulate system and evaluate it using novel multi-compartment dissolution apparatus. Atenolol loaded floating microspheres were prepared by emulsion solvent evaporation method using 3² full factorial design. Formulations F1 to F9 were prepared using two independent variables (polymer ratio and % polyvinyl alcohol) and evaluated for dependent variables (particle size, percentage drug entrapment efficiency and percentage buoyancy). The formulation(F8) with particle size of 329?±?2.69 µm, percentage entrapment efficiency of 61.33% and percentage buoyancy of 96.33% for 12?h was the of optimized formulation (F8). The results of factorial design revealed that the independent variables significantly affected the particle size, percentage drug entrapment efficiency and percentage buoyancy of the microspheres. In vitro drug release study revealed zero order release from F8 (98.33% in 12?h). SEM revealed the hollow cavity and smooth surface of the hollow microspheres.     

Preparation of alginate–CaCl2 microspheres as resveratrol carriers

Resveratrol-loaded calcium alginate microspheres for prolonged drug release were prepared by ionic gelation of alginate with calcium chloride (CaCl₂). Further, resveratrol-loaded calcium alginate microspheres were developed using two concentrations of alginate (0.5 and 1 % w/v) and CaCl₂ (0.5 and 1 M) and an encapsulator equipped with a 300-μm nozzle. The mean particle size of the microspheres was between 175.52 and 244.03 μm, and an encapsulation efficiency (EE) of over 95 % was observed. FTIR spectroscopy indicated a polyelectrolyte interaction between alginate and CaCl₂; alginate microsphere thermograms were analyzed by differential scanning calorimetry. X-ray diffraction shows the crystalline change of microspheres by cross linking. The release profiles and EE increased depending on the CaCl₂ concentration, and a slow initial burst release was observed on freeze-dried microspheres. These results indicate that resveratrol-loaded calcium alginate microspheres can be used as a potential resveratrol delivery system in the food industry.     

Sustained release optimized formulation of anastrozole-loaded chitosan microspheres: in vitro and in vivo evaluation

The purpose of this study was to develop sustained release formulation of anastrozole-loaded chitosan microspheres for treatment of breast cancer. Chitosan microspheres cross-linked with two different cross-linking agents viz, tripolyphosphate (TPP) and glutaraldehyde (GA) were prepared using single emulsion (w/o) method. A reverse phase HPLC method was developed and used for quantification of drug in microspheres and rat plasma. Influence of cross-linking agents on the properties of chitosan microspheres was extensively investigated. Formulations were characterized for encapsulation efficiency (EE), compatibility of drug with excipients, particle size, surface morphology, swelling capacity, erosion and drug release profile in phosphate buffer pH 7.4. EE varied from 30.4 ± 1.2 to 69.2 ± 3.2% and mean particle size distribution ranged from 72.5 ± 0.5 to 157.9 ± 1.5 μm. SEM analysis revealed smooth and spherical nature of microspheres. TPP microspheres exhibited higher swelling capacity, percentage erosion and drug release compared to GA microspheres. Release of anastrozole (ANS) was rapid up to 4 h followed by slow release status. FTIR analysis revealed no chemical interaction between drug and polymer. DSC analysis indicated ANS trapped in the microspheres existed in amorphous form in polymer matrix. The highest correlation coefficients (R ²) were obtained for Higuchi model, suggesting a diffusion controlled mechanism. There was significant difference in the pharmacokinetic parameters (AUC_0−∞, Kel and t_1/2) when ANS was formulated in the form of microspheres compared to pure drug. This may be attributed to slow release rate of ANS from chitosan microspheres and was detectable in rat plasma up to 48 h which correlates well with the in vitro release data.     

In vitro evaluation of spray-dried mucoadhesive micropheres for nasal administration.

Microspheres of disodium cromoglycate (DSCG) were prepared with either polyacrylic acid (Carbopol 934) or sodium carboxymethylcellulose (NaCMC) by the spray-drying technique. The arithmetic mean diameter of the spraydried particles ranged from 3.2 to 5.7 microns. The plain DSCG particles and the microspheres containing NaCMC were spherical and had a smooth surface, whereas the microspheres containing Carbopol 934 were more irregular and partly shrunken. The dissolution rate of the plain DSCG was prolonged when the drug was incorporated with the polymers. The more polymer the microspheres contained the slower the drug release rate. The in vitro mucoadhesion test showed that the plain DSCG was nearly as mucoadhesive as the the plain polymers. The microspheres of DSCG with either of the polymers were, however, clearly more mucoadhesive than the plain starting materials. The adsorption isotherms showed the hygroscopic nature of the polymers and DSCG. The hydration of the microspheres increased as a function of the drug content.     

In Vitro Evaluation of Albumin Microspheres Containing Actinomycin D

Abstract

Albumin microspheres containing actinomycin D were prepared by the heat stabilization method. The compata-bility of the drug with magnetite and the optimum stability of the drug in different pH were studied. Drug loaded albumin microspheres containing magnetite showed good magnetic response. Release of the drug was slow and continued for 7 days exhibiting sustained release property. The difference as regards to the size, shape, drug content and release rate from freshly prepared and freeze dried drug loaded albumin microspheres was negligible.     

Preparation, evaluation and bioavailability studies of indomethacin-bees wax microspheres

The present study envisages the preparation of microspheres containing indomethacin (IM) as model drug and bees wax as carrier, and to compare the in vitro release and pharmacokinetics of prepared IM formulation with commercially available oral formulation Microcid^®SR. The microsphere formulations were prepared by meltable emulsified dispersion and cooling induced solidification. Surface morphology of microspheres has been evaluated using scanning electron microscopy (SEM). The SEM images revealed the spherical shape of microspheres and more than 98.0% of the isolated microspheres were in the size range 115–855 μm. Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy studies indicated that the drug after encapsulation with bees wax was stable and compatible. A single dose randomized complete cross over study of IM (75 mg) microspheres was carried out on 8 healthy Albino sheeps. Plasma IM concentrations and other pharmacokinetic parameters obtained were statistically analyzed. The T _max, C _max, AUC_O-24 and T _1/2 values of Microcid^®SR and optimized formulation were 3.0 h, 2038 ± 51.31 ng/ml, 9528 ± 129.65 ng/ml h^?1, and 2.59 ± 0.02 h^?1; and 3.2 h, 1940 ± 22.61 ng/ml, 8751 ± 41.32 ng/ml h^?1, and 2.68 ± 0.02 h^?1, respectively. Beeswax microspheres showed controlled release and it can be concluded that both the prepared formulation and Microcid^®SR are bioequivalent.     

In Vitro Evaluation of Albumin Microspheres Containing Actinomycin D

Albumin microspheres containing actinomycin D were prepared by the heat stabilization method. The compata-bility of the drug with magnetite and the optimum stability of the drug in different pH were studied. Drug loaded albumin microspheres containing magnetite showed good magnetic response. Release of the drug was slow and continued for 7 days exhibiting sustained release property. The difference as regards to the size, shape, drug content and release rate from freshly prepared and freeze dried drug loaded albumin microspheres was negligible.     

Tracking the effect of microspheres size on the drug release from a microsphere/sucrose acetate isobutyrate (SAIB) hybrid depot in vitro and in vivo

The effects of particle size of microspheres on the drug release from a microsphere/sucrose acetate isobutyrate (SAIB) hybrid depot (m-SAIB) was investigated to develop a long-term sustained release drug delivery system with low burst release both in vitro and in vivo. A model drug, risperidone, was first encapsulated into PLGA microspheres with different particle sizes using conventional emulsification and membrane emulsification methods. The m-SAIB was prepared by dispersing the risperidone-microspheres in the SAIB depot. The drug release from m-SAIB was double controlled by the drug diffusion from the microspheres into SAIB matrix and the drug diffusion from the SAIB matrix into the medium. Large microspheres (18.95?±?18.88?µm) prepared by the conventional homogenization method exhibited porous interior structure, which contributed to the increased drug diffusion rate from microspheres into SAIB matrix. Consequently, m-SAIB containing such microspheres showed rapid initial drug release (C_max?=_?110.1?±54.2?ng/ml) and subsequent slow drug release (C_s(4–54d)=?2.7?±?0.8?ng/ml) in vivo. Small microspheres (5.91?±?2.24?µm) showed dense interior structure with a decreased drug diffusion rate from microspheres into SAIB matrix. The initial drug release from the corresponding m-SAIB was significantly decreased (C_max?=_?40.9?±?13.7?ng/ml), whereas the drug release rate from 4 to 54 d was increased (C_s(4–54d)=4.1?±?1.0?ng/ml). By further decreasing the size of microspheres to 3.38?±?0.70?µm, the drug diffusion surface area was increased, which subsequently increased the drug release from the m-SAIB. These results demonstrate that drug release from the m-SAIB can be tailored by varying the size of microspheres to reduce the in vivo burst release of SAIB system alone.     

Encapsulation and characterization of controlled release flurbiprofen loaded microspheres using beeswax as an encapsulating agent

The aim of the present study was to extend the use of flurbiprofen in clinical settings by avoiding its harmful gastric effects. For this purpose, we designed the controlled release solid lipid flurbiprofen microspheres (SLFM) by emulsion congealing technique. Drug was entrapped into gastro resistant biodegradable beeswax microspheres which were prepared at different drug/beeswax ratios 1:1, 1:2 and 1:3 using gelatin and tween 20 as emulsifying agents. The effect of emulsifiers and the effect drug/beeswax ratios were studied on hydration rate, encapsulating efficiency, micromeritic properties, scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (X-RD) analysis and in vitro drug release at pH 1.2 for 2 h and at pH 6.8 for 10 h. SEM revealed that microspheres made with tween 20 were smooth while microspheres made with gelatin showed porous morphology, however, they were all spherical in nature. The practical yield (recovery) showed a dependence on drug-beeswax ratio and it was variable from 53 to 84%. High loading encapsulating efficiency of flurbiprofen from 8 to 94% was achieved. FTIR and DSC analysis confirmed the absence of any drug polymer interaction indicating drug stability during microencapsulation. X-RD of pure flurbiprofen shows sharp peaks, which decreases on encapsulation, indicating decrease in the crystallinity of drug in microspheres. The micromeritic studies confirmed the presence of excellent and good flow properties of microspheres. Entrapment efficiency, morphology, practical yield, hydration rate, flow properties demonstrated their dependence on the HLB value of emulsifiers and emulsifiers with higher HLB were found more appropriate for effective microencapsulation of flurbiprofen. The release kinetics followed zero order mechanism of drug release at pH 6.8. Release pattern depends on the morphology of flurbiprofen microspheres and amount of beeswax used in the microspheres preparation. The microspheres prepared with high HLB values i.e., tween 20 showed effective control of drug release from microspheres. The absence of drug release at pH 1.2 proved the suitability of beeswax for its use as a gastro resistant material.     

Strontium-substituted,luminescent and mesoporous hydroxyapatite microspheres for sustained drug release

The multifunctional strontium (Sr)-substituted hydroxyapatite microsphere was prepared via hydrothermal method, in which the luminescent and controlled drug release functions can be realized. The structure and morphology of the as-prepared microspheres were studied by using XRD, FTIR, SEM, TEM, HR-TEM, BET method. The optical properties was investigated by using photoluminescence (PL) and XPS measurement. Then, the as-prepared multifunctional microspheres were performed as a drug delivery carrier using vancomycin as a model drug. The experimental results show that the composition, morphology, luminescent properties and drug storage/release behaviour were obviously influenced by the amount of Sr. The microspheres with Sr²⁺/(Ca²⁺ + Sr²⁺) = 0.3 of Sr substitution showed the maximum specific surface area, best pore structure and strongest PL intensity. All the samples presented remarkable sustained drug release kinetics. In addition, the PL intensity of SrHA in the drug delivery system increased with the cumulative release time (amount) of vancomycin, which would make the drug release might be possibly tracked by the change of the luminescent intensity. Our study indicated a potential prospect that the fabricated multifunctional SrHA mesoporous microspheres might be applied in the field of bone regeneration and drug delivery.     

Enteric-coated epichlorohydrin crosslinked dextran microspheres for site-specific delivery to colon

Abstract

Enteric-coated epichlorohydrin crosslinked dextran microspheres containing 5-Fluorouracil (5-FU) for colon drug delivery was prepared by emulsification-crosslinking method. The formulation variables studied includes different molecular weights of dextran, volume of crosslinking agent, stirring speed, time and temperature. Dextran microspheres showed mean entrapment efficiencies ranging between 77 and 87% and mean particle size ranging between 10 and 25?µm. About 90% of drug was released from uncoated dextran microspheres within 8?h, suggesting the fast release and indicated the drug loaded in uncoated microspheres, released before they reached colon. Enteric coating (Eudragit-S-100 and Eudragit-L-100) of dextran microspheres was performed by oil-in-oil solvent evaporation method. The release study of 5-FU from coated dextran microspheres was complete retardation in simulated gastric fluid (pH 1.2) and once the coating layer of enteric polymer was dissolved at higher pH (7.4 and 6.8), a controlled release of the drug from the microspheres was observed. Further, the release of drug was found to be higher in the presence of dextranase and rat caecal contents, indicating the susceptibility of dextran microspheres to colonic enzymes. Organ distribution and pharmacokinetic study in albino rats was performed to establish the targeting potential of optimized formulation in the colon.     

Development of pH-sensitive pectinate/alginate microspheres for colon drug delivery

The purposes of this study were to develop and evaluate calcium pectinate/alginate microspheres (PAMs) and to exploit their pH-sensitive properties for colon-targeted delivery of encapsulated cisplatin. PAMs were prepared using an electrospraying method. The PAMs, as cores, were then coated with Eudragit S100 using a polyelectrolyte multilayer coating technique in aqueous solution. The morphology of the microspheres was observed under scanning electron microscopy. In vitro drug release studies were performed in simulated gastrointestinal fluid, and the results indicated that approximately 5 % of the cisplatin was released from the Eudragit S100-coated PAMs, and 51 % of the cisplatin was released from the uncoated PAMs at 1 h. The release of cisplatin from the Eudragit S100-coated PAMs was more sustained in simulated gastric fluid than in simulated intestinal fluid due to the increased solubility of the coating polymer in media with pH >7.0. Drug release from the Eudragit S100-coated PAMs was best described by the Higuchi’s square root model. From these results, it was concluded that Eudragit S100-coated PAMs are a potential carrier for delivery of cisplatin to the colon.     

Evaluation and Optimization of Preparative Variables for Controlled-Release Floatable Microspheres Prepared by Poor Solvent Addition Method

The aim of this study was to evaluate and optimize preparative parameters for floatable theophylline microspheres prepared by the emulsion–solvent evaporation method. A three-factor three-level Box–Behnken design was employed using amount of poor solvent, temperature-increase rate and drug loading as independent factors, and percentage floating at 3 h and time required for 50% drug release as dependent variables. Simultaneous optimization of the parameters for maximum buoyancy and desirable drug release was conducted using a partitioned artificial neural network. A microsphere using 27.6% of drug loading, 0.29°C/min of temperature-increase rate, and 1.7 mL of poor solvent was identified for maximizing buoyancy and sustaining drug release.     

Pharmacokinetic and pharmacodynamic evaluation of floating microspheres of metformin hydrochloride

Metformin hydrochloride (MH), a biguanide antidiabetic, is the drug of choice in obese patients. It is well absorbed from the upper part of gastrointestinal tract and has oral bioavailability of 50% to 60%. The objective of this study was to formulate MH into floating microspheres in order to increase its residence time at the site of absorption and thus improve its bioavailability; and to extend the duration of action along with possibilities of dose reduction. Microspheres were prepared by emulsion solvent evaporation method and evaluated for particle size, entrapment efficiency, buoyancy, and in vitro release; and further characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and differential scanning calorimetry. The pharmacokinetic and pharmacodynamic evaluation of selected formulation was carried out in male Wistar diabetic rats. The data was statistically analyzed by unpaired t-test. A 3.5-fold increase in relative bioavailability was observed. The prolongation of half-life (t_1/2) from 4.5 ± 2.41 h to 14.12 ± 4.81 h indicated extended duration of action. Oral glucose tolerance test (OGTT) was analyzed by one-way analysis of variance followed by Dunnet multiple comparison test, a significant decrease (p < 0.05) in the blood glucose levels was observed when formulations were compared with control rats. Hence, MH floating microspheres were tested at 50 mg/kg and 100 mg/kg body weight, OGTT data showed nonsignificant difference (p >0.05). In conclusion, an effective oral antidiabetics treatment can be achieved by formulating MH into floating microspheres which results in increase in bioavailability along with extended duration of action resulting in possible reduction in dose.     

Chitosan-Drug Conjugate Microspheres: Preparation and Drug Release Properties of Microspheres Composed of the Conjugate of 2'- or 3'-(4-Carboxy-butyryl)-5- Fluorouridine with Chitosan

The conjugate microspheres (Chi-glu-FUR-m) were prepared by the dry-in-oil method using chitosan-5-fuorouridine conjugate. Chi-glu-FUR-m were characterized by drug content, particle shape and size, swelling property, and drug release. Their characteristics were compared with those of the simple microspheres (Chi/ FUR-m), which were prepared under similar conditions using a mixture of chitosan and 5-fluorouridine. Both microspheres prepared showed a high retention of the drug after preparation and similar particle size and shape. Swelling ratios after incubation in aqueous buflers of pH 7.4 for 6 hr were similar for both microspheres. Chi-glu-FUR-m swelled quickly in aqueous buffers of pH 7.4 and the disintegration was observed to occur gradually from 24 hr afrer the incubation. Chi-glu-FUR-m showed a gradual drug release (50% release time = 61 hr), while Chi/FUR-m released the drug very rapidly, Such characteristics of Chi-glu-FURm as swelling, slow disintegration, and gradual drug release propose its usefulness for localization or chemoembolization therapy.     

Cyclophosphamide Loaded Albumin Microspheres: Liver Entrapment and Fate in Mice

Abstract

Microspheres offer the possibility of target selectivity through choice of appropriate size or surface charecteristics, slow release of drug and also minimize systemic toxicity. The active substance of this investigation, cyclophosphamide (CP), interferes with the growth of cancer cells which are eventually destroyed. Since side effects of CP are frequently dose related, by incorporating low dose of CP to human serum albumin (HSA) microspheres, the normal body cells are not affected while the tumour cells are destroyed.

Cyclophosphamide microspheres were prepared by the modification of the method of Scheffel et al and Gürkan et al. 2,3-butanedione was used as a cross-linking agent. The albumin microspheres containing CP were labelled by ^99mTc by incorporating SnC1₂.2H₂0 at a concentration of 5% of the matrix material. All the microspheres used in this study ranged between 1–5 μm.

A suspension of ^99mTc labelled cyclophosphamide microspheres was injected into swiss albino mice intravenously. At 15 min, 30 rain, 6 h and 24 h mice were killed and the organs assayed for radioactivity accumulated in each organ. 1 hour later the radioactivity in the liver increased to 4.73 percent. By 24 hours, 2.68 percent of the radioactivity was found in the liver. Whereas the percentage of free cyclophosphamide at 1 and 24 hours was 2.22 and 2.57 percent, respectively. Based on the evidence obtained from these results, the application of CP loaded HSA microspheres seems advantages in accumulation in liver.     

Preparation and evaluation of insulin-loaded polylactide microspheres using factorial design

The aim of this work was to study the influence of the concentration and molecular weight of poly(DL-lactide) (PLA) on the characteristics and in vivo biological activity of protein-loaded microspheres. At the same time, an attempt was made to achieve further optimization of the formulation. In the study, insulin was chosen as a model of protein drugs. Nine formulations of injectable insulin-loaded PLA microspheres were prepared using an emulsification and solvent evaporation process according to a factorial design. The trapping efficiency, drug loading, and the drop percentages of blood glucose levels at 24 hr and 72 hr in mice were used to evaluate the formulations. The results showed that PLA molecular weight and, especially, PLA concentration exerted influences on the characteristics and in vivo biological activity of insulin-loaded microspheres. The drug-trapping efficiency increased with the increase of the polymer concentration. The drug loading decreased with the increase of the polymer concentration and was not obviously affected by PLA molecular weight. The drop percentage of blood glucose level at 24 hr increased with the increase of polymer concentration and molecular weight. At 72 hr, the drop percentages of blood glucose levels were slightly increased with the increase of PLA concentration and then significantly decreased after the PLA concentration was above 150 mg/ml. An optimized formulation was prepared with PLA-10k at a concentration of 200 mg/ml. The experimental values of the response variables were close to the predicted values. The results suggest that the in vivo release behavior should be taken into consideration in the design of protein-loaded PLA microspheres.     

Preparation and Evaluation of Insulin-Loaded Polylactide Microspheres Using Factorial Design

The aim of this work was to study the influence of the concentration and molecular weight of poly(DL-lactide) (PLA) on the characteristics and in vivo biological activity of protein-loaded microspheres. At the same time, an attempt was made to achieve further optimization of the formulation. In the study, insulin was chosen as a model of protein drugs. Nine formulations of injectable insulin-loaded PLA microspheres were prepared using an emulsification and solvent evaporation process according to a factorial design. The trapping efficiency, drug loading, and the drop percentages of blood glucose levels at 24 hr and 72 hr in mice were used to evaluate the formulations. The results showed that PLA molecular weight and, especially, PLA concentration exerted influences on the characteristics and in vivo biological activity of insulin-loaded microspheres. The drug-trapping efficiency increased with the increase of the polymer concentration. The drug loading decreased with the increase of the polymer concentration and was not obviously affected by PLA molecular weight. The drop percentage of blood glucose level at 24 hr increased with the increase of polymer concentration and molecular weight. At 72 hr, the drop percentages of blood glucose levels were slightly increased with the increase of PLA concentration and then significantly decreased after the PLA concentration was above 150 mg/ml. An optimized formulation was prepared with PLA-10k at a concentration of 200 mg/ml. The experimental values of the response variables were close to the predicted values. The results suggest that the in vivo release behavior should be taken into consideration in the design of protein-loaded PLA microspheres.     

Aqueous Preparation and Evaluation of Albumin‐Chitosan Microspheres Containing Indomethacin

Controlled‐release egg albumin‐chitosan microspheres containing indomethacin as a model drug were successfully prepared by coacervation method. The proposed method can offer a simple method for microsphere preparation in an aqueous system with the elimination of the use of organic solvents that are usually needed in conventional techniques of microencapsulation. The interaction between negatively charged egg albumin molecules in phosphate buffer, pH 7.2, or sodium hydroxide solution and positively charged chitosan molecules dissolved in diluted acetic acid to form an insoluble precipitate was the principle for the formation of the microspheres. The effects of many process variables, such as amount of formaldehyde as a cross‐linking agent, stirring time, final pH of encapsulation medium, initial drug loading, and albumin concentration or albumin‐to‐chitosan weight ratio, on the properties of the prepared microspheres were investigated. Incorporation efficiencies of the microspheres to the drug were high in most cases and ranged between 63.3 ± 3.6% and 92.39 ± 3.2%, while particle sizes were 435.2 ± 12.6 up to 693.9 ± 34.6 µm for the different tested batches. On the other hand, the values of angles of repose and compressibility indices were in the range of 23.5 ± 0.4 to 32.0 ± 0.7 degrees and 11.1 ± 0.7% to 23.6 ± 0.7% respectively, which indicate overall good free flowing nature of the microspheres of all batches. The maximum required amount of the cross‐linking agent was determined to avoid excessive unnecessary chemicals. It was also noticed that excessive time of stirring and excessive initial drug loading are not recommended as it may lead to microspheres of low properties. The pH of the encapsulation media (pH 3.77 up to pH 4.91) significantly affected the properties of the microspheres. As the pH of the encapsulation media was increased, the incorporation efficiency, particle size, and flowability decreased, along with increase of drug release rate, which could be related to incomplete cross linking of the microspheres matrix. It was also observed that high concentration of albumin solution and accordingly the increase of albumin‐to‐chitosan weight ratio were accompanied with increases in incorporation efficiency and particle size with improved microsphere flowability and slow indomethacin release. Thus, the proposed microspheres showed the ability to control the release of indomethacin, and their properties were highly affected by many process variables that could be controlled to obtain an optimized system.     

In vitro and in vivo studies on a novel solid dispersion of repaglinide using polyvinylpyrrolidone as the carrier

In order to improve the dissolution and absorption of the water insoluble drug repaglinide, a solid dispersion was developed by solvent method using polyvinylpyrrolidone K30 (PVP K30) as the hydrophilic carrier for the first time. Studies indicated that both solubility and the dissolution rate of repaglinide were significantly increased in the solid dispersion system compared with that of repaglinide raw material or physical mixtures. The repaglinide solid dispersions with PVP K30 solid state was characterized by polarizing microscopy, differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). DSC and XRD studies indicated that repaglinide existed in an amorphous form in the solid dispersion. FT-IR analysis demonstrated the presence of intermolecular hydrogen bonding between repaglinide and PVP K30 in the solid dispersion. In the in situ gastrointestinal perfusion experiment, solid dispersion was shown to remarkably enhance the absorption of repaglinide in stomach and all segments of intestine. In vivo pharmacokinetic study in rats showed that immediate and complete release of repaglinide from the solid dispersion resulted in rapid absorption that significantly increased the bioavailability and the maximum plasma concentration over repaglinide raw material. These results demonstrated PVP K30 was an appropriate carrier for solid dispersion of repaglinide, with increased dissolution and oral absorption.