Single-dose bioavailability of oral and intramuscular thiocolchicoside in healthy volunteers

A single dose of 8 mg of thiocolchicoside was administered to 12 healthy volunteers according to a Latin square design, either as tablets (reference), oral solution, or intramuscular injection. Serum thiocolchicoside concentrations showed an absorption phase followed by a biexponential decay with a terminal half-life (t_1/2β) of approximately 5 h, similar for the three formulations. The relative bioavailability of both oral formulations was approximately 25%, compared to the intramuscular formulation. There was a trend for the oral solution to have a slightly larger AUC and C_max, as well as a slightly shorter T_max, than the tablet formulation. However, the comparison of the two oral forms did not show statistically significant differences in the pharmacokinetic parameters C_max, T_max, and AUC, suggesting that the Coltramyl^® tablets have an adequate in vivo dissolution profile.     

Revaprazan-loaded surface-modified solid dispersion: physicochemical characterization and in vivo evaluation

The purpose of this research was to develop a novel revaprazan-loaded surface-modified solid dispersion (SMSD) with improved drug solubility and oral bioavailability. The impact of carriers on aqueous solubility of revaprazan was investigated. HPMC and Cremophor A25 were selected as an appropriate polymer and surfactant, respectively, due to their high drug solubility. Numerous SMSDs were prepared with various concentrations of carriers, using distilled water, and the drug solubility of each was assessed. Moreover, the physicochemical properties, dissolution and pharmacokinetics of selected SMSD in rats were assessed in comparison to revaprazan powder. Of the SMSDs assessed, the SMSD composed of revaprazan/HPMC/Cremophor A25 at the weight ratio of 1:0.28:1.12 had the most enhanced drug solubility (～6000-fold). It was characterized by particles with a relatively rough surface, suggesting that the carriers were attached onto the surface of the unchanged crystalline revaprazan powder. It had a significantly higher dissolution rate, AUC and C_max, and a faster T_max value in comparison to revaprazan powder, with a 5.3-fold improvement in oral bioavailability of revaprazan. Therefore, from an environmental perspective, this SMSD system prepared with water, and without organic solvents, should be recommended as a revaprazan-loaded oral pharmaceutical alternative.     

Biowaiver monographs for immediate-release solid oral dosage forms: Ketoprofen

Literature and experimental data relevant to the decision to allow a waiver of in vivo bioequivalence (BE) testing for the approval of immediate‐release (IR) solid oral dosage forms containing ketoprofen are reviewed. Ketoprofen's solubility and permeability, its therapeutic use and therapeutic index, pharmacokinetic properties, data related to the possibility of excipient interactions, and reported BE/bioavailability (BA)/dissolution data were taken into consideration. The available data suggest that according to the current Biopharmaceutics Classification System (BCS) and all current guidances, ketoprofen is a weak acid that would be assigned to BCS Class II. The extent of ketoprofen absorption seems not to depend on formulation or excipients, so the risk of bioinequivalence in terms of area under the curve is very low, but the rate of absorption (i.e., BE in terms of peak plasma concentration, C_max) can be altered by formulation. Current in vitro dissolution methods may not always reflect differences in terms of C_max for BCS Class II weak acids; however, such differences in absorption rate are acceptable for ketoprofen with respect to patient risks. As ketoprofen products may be taken before or after meals, the rate of absorption cannot be considered crucial to drug action. Therefore, a biowaiver for IR ketoprofen solid oral dosage form is considered feasible, provided that (a) the test product contains only excipients present also in IR solid oral drug products containing ketoprofen, which are approved in International Conference on Harmonisation or associated countries, for instance, as presented in this paper; (b) both the test drug product and the comparator dissolve 85% in 30 min or less in pH 6.8 buffer; and (c) test product and comparator show dissolution profile similarity in pH 1.2, 4.5, and 6.8. When one or more of these conditions are not fulfilled, BE should be established in vivo.     

Physicochemical characterization and in vivo evaluation of flurbiprofen-loaded solid dispersion without crystalline change

To develop a novel flurbiprofen-loaded solid dispersion without crystalline change, various flurbiprofen-loaded solid dispersions were prepared with water, sodium carboxylmethyl cellulose (Na-CMC), and Tween 80. The effect of Na-CMC and Tween 80 on aqueous solubility of flurbiprofen was investigated. The physicochemical properties of solid dispersions were investigated using SEM, DSC, and X-ray diffraction. The dissolution and bioavailability in rats were evaluated compared to commercial product. Unlike conventional solid dispersion systems, the flurbiprofen-loaded solid dispersion gave a relatively rough surface and changed no crystalline form of drug. These solid dispersions were formed by attaching hydrophilic carriers to the surface of drug without crystal change, resulting in changing the hydrophobic drug to hydrophilic form. Furthermore, the flurbiprofen-loaded solid dispersion at the weight ratio of flurbiprofen/Na-CMC/Tween 80 of 6/2.5/0.5 improved ～ 60-fold drug solubility. It gave higher AUC, T_max, and C_max compared to commercial product. The solid dispersion improved almost 1.5-fold bioavailability of drug compared to commercial product in rats. Thus, the flurbiprofen-loaded solid dispersion would be useful to deliver poorly water-soluble flurbiprofen with enhanced bioavailability without crystalline change.     

Correlation between dissolution rate and bioavailability of different commercial mefenamic acid capsules

A dissolution test was performed with five brands of 250 mg mefenamic acid capsule products available on the market. Three of them, the fast dissolving A and the slow dissolving D and E were subjected to a bioavailability study using a commercially available suspension as the reference. The products were administered orally in a cross-over design to 6 healthy men, and then parameters for the bioavailability were calculated from the plasma concentration-time curve. Analysis of variance indicated several significant differences among the products with respect to C_max, T_max and AUC. The relative availabilities of A, D and E were 86, 81 and 28%, respectively, with the AUC value (0-7 h) for the suspension as 100%.No correlation was observed between the in vitro dissolution rate of the drug from the capsules and the in vivo data, because the dispersing behavior of the capsule exerted a marked influence on its in vitro dissolution rate. To eliminate the influence of the capsule disintegrating process, a dissolution test was done on the contents of the capsules. A good correlation was found between the bioavailability and the dissolution rate of the drug from the capsule contents.Product E with the lowest bioavailability was passed through a 200-mesh sieve, placed in a new capsule, and tested for its bioavailabilky in humans. The AUC value was greater than that of the original product and the bioavailability was about equal to that of the suspension. The in vitro dissolution rate of the drug from the pulverized product E was also markedly increased.     

Preparation,characterization, and in vitro/vivo evaluation of polymer-assisting formulation of atorvastatin calcium based on solid dispersion technique

 Due to low solubility and bioavailability, atorvastatin calcium is confronted with challenge in conceiving appropriate formulation. Solid dispersion of atorvastatin calcium was prepared through the solvent evaporation method, with Poloxamer 188 as hydrophilic carriers. This formulation was then characterized by scanning electron microscopy, differential scanning calorimetry,powder X-ray diffraction and fourier transform infrared spectroscopy. Moreover, all these studies suggested the conversion of crystalline atorvastatin calcium. In addition, the drug solubility studies as well as dissolution rates compared with bulk drug and market tablets Lipitor were also examined. Furthermore, the study investigated the pharmacokinetics after oral administration of Lipitor and solid dispersion. And the AUC0–8 h and Cmax increased after taking ATC-P188 solid dispersion orally compared with that of Lipitor. All these could be demonstrated that ATC-P188 solid dispersions would be prospective means for enhancing higher oral bioavailability of ATC.     

Development and Internal Validation of an In Vitro-in Vivo Correlation for a Hydrophilic Metoprolol Tartrate Extended Release Tablet Formulation

Purpose. To develop and validate internally an in vitro-in vivo correlation (IVIVC) for a hydrophilic matrix extended release metoprolol tablet. Methods. In vitro dissolution of the metoprolol tablets was examined using the following methods: Apparatus II, pH 1.2 & 6.8 at 50 rpm and Apparatus I, pH 6.8, at 100 and 150 rpm. Seven healthy subjects received three metoprolol formulations (100 mg): slow, moderate, fast releasing and an oral solution (50 mg). Serial blood samples were collected over 48 hours and analyzed by a validated HPLC assay using fluorescence detection. The f ₂ metric (similarity factor) was used to analyze the dissolution data. Correlation models were developed using pooled fraction dissolved (FRD) and fraction absorbed (FRA) data from various combinations of the formulations. Predicted metoprolol concentrations were obtained by convolution of the in vivo dissolution rates. Prediction errors were estimated for C_max and AUC to determine the validity of the correlation. Results. Apparatus I operated at 150 rpm, and pH of 6.8 was found to be the most discriminating dissolution method. There was a significant linear relationship between FRD and FRA when using either two or three of the formulations. An average percent prediction error for C_max and AUC for all formulations of less than 10% was found for all IVIVC models. Conclusions. The relatively low prediction errors for C_max and AUC observed strongly suggest that the metoprolol IVIVC models are valid. The average percent prediction error of less than 10% indicates that the correlation is predictive and allows the associated dissolution data to be used as a surrogate for bioavailability studies.     

Preparation and evaluation of ibuprofen-loaded microemulsion for improvement of oral bioavailability

The purpose of the current study was to improve the solubility of ibuprofen, a poorly water-soluble drug, in a microemulsion system that is suitable for oral administration. Microemulsion was prepared using different sorts of oils, surfactants, and co-surfactants. Pseudo-ternary phase diagrams were used to evaluate the microemulsion domain. The formulations were characterized by solubility of the drug in the vehicle, droplet size, and drug release. The optimal formulation consists of 17% Labrafil M 1944CS, 28% Cremophor RH40/Transcutol P (3:1, w/w), and 55% water, with a maximum solubility of ibuprofen up to 60.3?mg/ml. The mean droplet size of microemulsion was 57?nm. The pharmacokinetic study of microemulsion was performed in rats and compared with granule formulation. The microemulsion has significantly increased the C_max and area under the curve (AUC) compared to that of the granule (p?<?0.05). The relative bioavailability of ibuprofen in microemulsions was 1.9-fold higher than that of the granule. These results indicated that this novel microemulsion is a useful formulation for enhancing the oral bioavailability of ibuprofen.     

Preparation,in vitro and in vivo evaluation of solid-state self-nanoemulsifying drug delivery system (SNEDDS) of vitamin A acetate

Vitamin A self-nanoemulsifying drug delivery system (SNEDDS), which comprises soybean oil, Cremophor EL, and Capmul MCM-C8, was prepared and mixed with different grades of Avicel to produce homogenized powders. The resultant powders were compressed into tablets. The prepared tablets were characterized for their thickness, hardness, friability, disintegration time, and dissolution rate. In addition, the relative bioavailability of the tablets in comparison to solid-state Vitamin A oily solution (SSVAOS) tablets was investigated in rats. Vitamin A dissolution rate was markedly different from one formulation to another. From the bioavailability data, it was observed that Vitamin A SNEDD tablets have higher bioavailability (relative bioavailability 143.68%) compared with SSVAOS tablets. The AUC and C_max of Vitamin A SNEDD tablets were found to be significantly different from that of SSVAOS tablets.     

Comparative bioavailability of josamycin,a macrolide antibiotic,from a tablet and solution and the influence of dissolution on in vivo release

The bioavailability of josamycin from a tablet formulation (2 × Josacine® 500 mg tablets) was investigated and compared with the bioavailability of a solution (containing 1 g drug and buffered at pH 4.0) following administration to six healthy human volunteers. Bioavailability profiles for the solution indicated that the drug was inherently rapidly absorbed with a mean C_max of 1.64±0.67 mg L⁻¹ attained at a mean t_max of 0.39±0.08 h. The AUC_0–last was 1.510±0.687 mg h L⁻¹. Bioavailability was significantly lower from the tablets than from the solution. Highly variable serum concentration–time profiles were obtained from the tablets and C_max values ranged from 0.05 to 0.71 mg L⁻¹ with a t_max range of 0.33–2.0 h. AUC_0–last values ranged from 0.03 to 0.95 mg h L⁻¹. Dissolution of josamycin from the tablets was generally unaffected at low pH (pH 1.2–5.0), but, rather, limited predominantly by tablet disintegration. However, dissolution was increasingly limited as the pH increased from 5.0 to 9.0. Besides poor disintegration, the particularly low intrinsic dissolution rate and solubility of josamycin at these pH values is likely to further reduce the dissolution rate. Comparison of the solution and tablet serum concentration–time profiles suggests that the absorption of josamycin from the tablets was dissolution rate limited. This is supported by the in vitro dissolution–pH topogram, which suggests that dissolution will be particularly rate limiting if dissolution of whole or parts of tablets occurs in gastro-intestinal fluid above pH 5.0. © 1998 John Wiley & Sons, Ltd.     

Solubilized formulation of olmesartan medoxomil for enhancing oral bioavailability

Olmesartan medoxomil (OLM) is an antihypertensive angiotensin II receptor blocker. OLM has a low bioavailability (BA), approximately 26% in humans, due to its low water solubility and efflux by drug resistance pumps in the gastrointestinal tract. Self-microemulsifying drug delivery system (SMEDDS), which is easily emulsified in aqueous media under gentle agitation and digestive motility, was formulated to increase the oral BA of OLM. Among the surfactants and oils studied, Capryol 90, Tween 20, and Tetraglycol were chosen and combined at a volume ratio of 1:6:3 on the basis of equilibrium solubility and phase diagram experiments. The mean droplet size of SMEDDS was 15 nm. In an oral absorption study in rats, SMEDDS formulation brought faster absorption compared to suspension, showing a T _max value of 0.2 hr. The C _max and AUC values of SMEDDS formulation were significantly higher than those of suspension, revealing a relative BA of about 170%. Our study demonstrated the potential usefulness of SMEDDS for the oral delivery of poorly absorbable compounds, including OLM.     

Comparative in vitro and in vivo evaluation of three tablet formulations of amiodarone in healthy subjects

Background and the purpose of the study

The relative in vivo bioavailability and in vitro dissolution studies of three chemically equivalent amiodarone generic products in healthy volunteers was evaluated in three separate occasions. The possibility of a correlation between in vitro and in vivo performances of these tablet formulations was also evaluated.

Methods

The bioequivalence studies were conducted based on a single dose, two-sequence, cross over randomized design. The bioavailability was compared using AUC_0–72, AUC_0–8, C_max and T_max. Similarity factor, dissolution efficiency (DE), and mean dissolution time (MDT) was used to compare the dissolution profiles. Polynomial linear correlation models were tested using either MDT vs mean residence time (MRT) or fraction of the drug dissolved (FRD) vs fraction of the drug absorbed (FRA).

Results

Significant differences were found in the dissolution performances of the tested formulations and therefore they were included in the development of the correlation. The 90% confidence intervals of the log-transformed AUC0-72, AUC_0–8, and C_max of each two formulations in each bioequivalence studies were within the acceptable range of 80–125%. Differences were not observed between the untransformed T_max values. Poor correlation was found between MRT and MDT of the products. A point-to-point correlation which is essential for a reliable correlation was not obtained between pooled FRD and FRA. The dissolution condition which was used for amiodarone tablets failed for formulations which were bioequivalent in vivo and significant difference between the dissolution characteristics of products (f2<50) did not reflect their in vivo properties.

Major conclusions

Bioequivalence studies should be considered as the only acceptable way to ensure the interchangeability and in vivo equivalence of amiodarone generic drug products. The dissolution conditions used of the present study could be used for routine and in-process quality control of amiodarone tablet formulations.     

Biowaiver extension potential and IVIVC for BCS Class II drugs by formulation design: Case study for cyclosporine self-microemulsifying formulation

The objective of this work was to suggest the biowaiver potential of biopharmaceutical classification system (BCS) Class II drugs in self-microemulsifying drug delivery systems (SMEDDS) which are known to increase the solubility, dissolution and oral absorption of water-insoluble drugs. Cyclosporine was selected as a representative BCS Class II drug. New generic candidate of cyclosporine SMEDDS (test) was applied for the study with brand SMEDDS (reference I) and cyclosporine self-emulsifying drug delivery systems (SEDDS, reference II). Solubility and dissolution of cyclosporine from SMEDDS were critically enhanced, which were the similar behaviors with BCS class I drug. The test showed the identical dissolution rate and the equivalent bioavailability (0.34, 0.42 and 0.68 of p values for AUC_0→24h, C_max and T_max, respectively) with the reference I. Based on the results, level A in vitro-in vivo correlation (IVIVC) was established from these two SMEDDS formulations. This study serves as a good example for speculating the biowaiver extension potential of BCS Class II drugs specifically in solubilizing formulation such as SMEDDS.     

Pharmacokinetic evaluation of oral fenofibrate nanosuspensions and SLN in comparison to conventional suspensions of micronized drug

An increasing number of newly developed drugs show bioavailability problems due to poor water solubility. Formulating the drugs as nanosuspensions may help to overcome these problems by increasing saturation solubility and dissolution velocity. In the present study the bioavailability of the poorly soluble fenofibrate following oral administration was investigated in rats. Four formulations were tested: a nanosuspension type DissoCube(R), one solid lipid nanoparticle (SLN) preparation and two suspensions of micronized fenofibrate as reference formulations, one suspension in sirupus simplex and a second in a solution of hydroxyethy-cellulose in physiological saline. Both colloidal drug delivery systems showed approximately two-fold bioavailability enhancements in terms of rate and extent compared to the reference formulations. No significant differences were found in AUC(0-22 h) as well as in C(max) and t(max) between the two colloidal delivery systems. In conclusion, nanosuspensions may be a suitable delivery system to improve the bioavailability of drugs with low water solubility.     

Role of lipid-based excipients and their composition on the bioavailability of antiretroviral self-emulsifying formulations

Abstract

The objective of this study was to develop self-emulsifying drug delivery system (SEDDS) to improve solubility and enhance the oral absorption of the poorly water-soluble drug, nevirapine. This lipid-based formulation may help to target the drug to lymphoid organs where HIV-1 virus resides mainly. The influence of the oil, surfactant and co-surfactant types on the drug solubility and their ratios on forming efficient and stable SEDDS were investigated in detail. Two SEDDS (F1 and F2) were prepared and characterized by morphological observation, droplet size and zeta potential determination, cloud point measurement and in vitro diffusion study. The influence of droplet size on the absorption from formulations with varying concentration of oil and surfactant was also evaluated from two self-emulsifying formulations. Oral bioavailability of nevirapine SEDDS was checked by using rat model. Results of diffusion rate and oral bioavailability of nevirapine SEDDS were compared with marketed suspension. The absorption of nevirapine from F1 and F2 showed 1.92 and 1.98-fold increase (p?<?0.05) in relative bioavailability, respectively, compared with that of the suspension. There was no statistical significant difference (p?<?0.05) between F1 and F2 in their AUC and C_max. This indicated that there was apparent poor correlation between the droplet size and in vivo absorption. However, nevirapine in SEDDS showed higher ex vivo stomach and intestinal permeability and in vivo absorption than the marketed suspension, suggesting that the SEDDS may be a useful delivery system for targeting nevirapine to lymphoid organs.     

Development of a novel bi-coated combination capsule containing mosapride and probiotics for irritable bowel syndrome

Abstract

The objective of this study was to develop a novel combination product containing mosapride and probiotics for the treatment of irritable bowel syndrome. Enteric-coated hard gelatin capsules containing probiotics were prepared to protect acid-labile probiotics from the stomach by spray coating with hydroxypropylmethylcellulose phthalate, and then coated with various hydrophilic polymer solutions containing mosapride. The influence of different hydrophilic polymers on the aqueous solubility and dissolution of sparingly soluble mosapride from the capsule was investigated to select the one which imparted highest solubility to mosapride in an aqueous solution. The physicochemical properties of the hydrophilic polymer coating were assessed using SEM and DSC. In addition, the bioavailability of the mosapride-coated capsule in beagle dog was evaluated and compared to that of conventional mosapride tablet (CMT). Based on DSC studies, the mosapride in polymer coating underwent amorphization or molecular dispersion. The enteric-capsule coated with mosapride/HPMC exhibited improved solubility of mosapride at acidic pH and showed significantly improved AUC (1.5-fold) and C_max (1.6-fold) compared to the CMT. In conclusion, drug/polymer coated enteric gelatin capsule can be an alternative technique for co-delivery of sparingly water-soluble drug and acid-labile drug for enhanced solubility and bioavailability as well as for protection from acid degradation.     

The effect of antacid,metoclopramide, and propantheline on the bioavailability of metoprolol and atenolol

Concomitant administration of antacid increased the maximum concentration (Cp_max) and the area under the plasma concentration-time curve (AUC) of 100 mg oral dose of metoprolol by 25 per cent (p< 0.05) and 11 per cent (p < 0.1) respectively. For atenolol the opposite effect was observed and Cp_max and AUC were decreased by 37 and 33 per cent respectively (p< 0.02). In both cases the antacid did not affect the time-course of the drug in the plasma. Pretreatment with metoclopramide did not affect the time-course of atenolol in the plasma or its bioavailability. Propantheline prolonged the absorption phase of atenolol and the time of peaking (t_max) was shifted from 2.1 to 4.5 h. Cp_max of atenolol was essentially unchanged by propantheline pretreatment while the AUC was increased by 36 per cent. It is concluded that the negative effect of the antacid on the bioavailability of atenolol is caused by a reduction in the in vivo dissolution rate due to increased gastric pH. The positive effect of propantheline might be due either to more efficient absorption of atenolol in the upper part of the intestine or more extensive dissolution of the drug as a result of prolonged contact with gastric juice or a combination of these factors.     

Development of gastroretentive drug delivery system for cefuroxime axetil: In vitro and in vivo evaluation in human volunteers

The objective of this investigation was to develop the cefuroxime axetil sustained-release floating tablets to prolong the gastric residence time and compare their pharmacokinetic behavior with marketed conventional tablets (Zocef). The floating tablets were developed using polymers like HPMC K4M and HPMC K100M alone, and polymer combination of HPMC K4M and Polyox WSR 303 by effervescent technique. Tablets were prepared by slugging method and evaluated for their physical characteristics, in vitro drug release, and buoyancy lag time. The best formulation (F10) was selected based on in vitro characteristics and used in vivo radiographic and bioavailability studies in healthy human volunteers. All the formulations could sustain drug release for 12 h. The dissolution profiles were subjected to various kinetic release models and it was found that the mechanism of drug release followed Peppas model. The in vivo radiographic studies revealed that the tablets remained in stomach for 225±30 min. Based on in vivo performance, the developed floating tablets showed superior bioavailability than Zocef tablet. Based on in vivo performance significant difference was observed between C_max, t_max, t_1/2, AUC_0–∞, and mean residence time of test and reference (p<0.05). The increase in relative bioavailability of test was 1.61 fold when compared to reference.     

Nanosizing of valsartan by high pressure homogenization to produce dissolution enhanced nanosuspension: pharmacokinetics and pharmacodyanamic study

Purpose: The purpose of the present study was to formulate and evaluate nanosuspension of Valsartan (VAL), a poorly water soluble and low bioavailable drug (solubility of 0.18?mg?mL^?1; 23% of oral bioavailability) with the aim of improving the aqueous solubility thus the bioavailability and consequently better anti-hypertensive activity.

Methods: Valsartan nanosuspension (VAL-NS) was prepared using high-pressure homogenization followed by lyophilisation. The screening of homogenization factors influencing nanosuspension was done by 3-factorial, 3-level Box-Behnken statistical design. Model suggested the influential role of homogenization pressure and cycles on drug nanosizing. The optimized formulation containing Poloxamer^?188 (PXM 188) was homogenized for 2 cycles at 500 and 1000?bar, followed by 5 cycles at 1500 bars.

Results: The size analysis and transmission electron microscopy showed nanometric size range and uniform shape of the nanosuspension. The in vitro dissolution showed an enhanced release of VAL from nanosuspension (VAL-NS) compared to physical mixture with PXM 188. Pharmacodynamic results showed that, oral administration of VAL-NS significantly lowered (p?≤?0.001) blood pressure in comparison to non-homogenized VAL (VAL-Susp) in Wistar rat. The level of VAL in rat plasma treated with VAL-NS showed significant difference (p?≤?0.005) in C_max (1627.47?±?112.05?ng?mL^?1), T_max (2.00?h) and AUC_0→24 (13279.2?±?589.426?ng?h?mL^?1) compared to VAL-Susp that was found to be 1384.73?±?98.76?ng?mL^?1, 3.00?h and 9416.24?±?218.48?ng?h?mL^?1 respectively. The lower T_max value, proved the enhanced dissolution rate of VAL.

Conclusion: The overall results proved that newly developed VAL-NS increased the plasma bioavailability and pharmacodyanamic potential over the reference formulation containing crude VAL.     

Development of raloxifene-solid dispersion with improved oral bioavailability via spray-drying technique

The purpose of this study was to develop a raloxifene-loaded solid dispersion with enhanced dissolution rate and bioavailability via spray-drying technique. Solid dispersions of raloxifene (RXF) were prepared with PVP K30 at weight ratios of 1:4, 1:6 and 1:8 using a spray-drying method, and characterized by differential scanning calorimetry, X-ray powder diffraction, scanning electron microscopy, and solubility and dissolution tests. The bioavailability of the solid dispersion in rats was also evaluated compared to those of RXF powder and commercial product. Results showed that the RXF-loaded solid dispersion was in amorphous form with increased solubility and dissolution rate. The absorption of RXF from solid dispersion resulted in approximately 2.6-fold enhanced bioavailability compared to pure drug. Moreover, RXF-loaded solid dispersion gave similar AUC, C_max and T_max values to the commercial product, suggesting that it was bioequivalent to the commercial product in rats. These findings suggest that an amorphous solid dispersion of RXF could be a viable option for enhancing the oral bioavailability of RXF.