Development of novel itraconazole-loaded solid dispersion without crystalline change with improved bioavailability

To develop a novel itraconazole-loaded solid dispersion without crystalline change with improved bioavailability, various itraconazole-loaded solid dispersions were prepared with water, polyvinylpyrroline, poloxamer and citric acid. The effect of carriers on aqueous solubility of itraconazole was investigated. Their physicochemical properties were investigated using SEM, DSC, and powder X-ray diffraction. The dissolution, bioavailability in rats and stability of solid dispersions were evaluated. Unlike conventional solid dispersion system, the itraconazole-loaded solid dispersion with relatively rough surface did not change crystalline form of drug. Our DSC and powder X-ray diffraction results suggested that this solid dispersion was formed by attaching hydrophilic carriers to the surface of drug without crystal change, resulting in conversion of the hydrophobic drug to hydrophilic form. The itraconazole-loaded solid dispersion at the weight ratio of itraconazole/polyvinylpyrroline/poloxamer of 10/2/0.5 gave maximum drug solubility of about 20 μg/mL. It did not change the crystalline form of drug for at least 6 months, indicating that it was physically stable. It gave higher AUC, C_max and T_max compared to itraconazole powder and similar values to the commercial product, suggesting that it was bioequivalent to commercial product in rats. Thus, it would be useful to deliver a poorly water-soluble itraconazole without crystalline change with improved bioavailability.     

Enhanced solubility and bioavailability of flurbiprofen by cycloamylose

The effect of cycloamylose on the aqueous solubility of flurbiprofen was investigated. To improve the solubility and bioavailability of flurbiprofen (poor water solubility), a solid dispersion was spray dried with a solution of flurbiprofen and cycloamylose at a weight ratio of 1:1. The physicochemical properties of solid dispersions were investigated using SEM, DSC, and X-ray diffraction. The dissolution and bioavailability in rats were evaluated compared with a commercial product. Cycloamylose increased solubility of flurbiprofen approximately 12-fold and dissolution of it by 2-fold. Flurbiprofen was present in an unchanged crystalline state, and cycloamylose was a solubilizing agent for flurbiprofen in this solid dispersion. Furthermore, the dispersion gave higher AUC and C_max values compared with the commercial product, indicating that it improved the oral bioavailability of flurbiprofen in rats. Thus, the solid dispersion may be useful to deliver flurbiprofen with enhanced bioavailability without changes in crystalline structure.     

A novel solid dispersion system for natural product-loaded medicine: silymarin-loaded solid dispersion with enhanced oral bioavailability and hepatoprotective activity

Abstract

A surface-attached silymarin-loaded solid dispersion with improved dissolution profile and enhanced oral bioavailability was formulated using silymarin, polyvinylpyrrolidone (PVP) and Tween 80 in water. In this solid dispersion, hydrophilic PVP was adhered onto the surface of crystalline drug rendering silymarin hydrophilic without changing its crystallinity. The drug solubility from the optimised solid dispersion prepared with silymarin/PVP/Tween 80 at the weight ratio of 5/2.5/2.5 increased by almost 650-fold compared to drug powder. The drug was physically and chemically stable in the solid dispersion for at least 6 months. Moreover, the solid dispersion enhanced the oral bioavailability of the drug in rats by almost 3-fold compared to the commercial product. The silymarin-loaded solid dispersion also exhibited advanced hepatoprotective bioactivity against CCl₄-induced liver damage compared to silymarin or the commercial product. Thus, this silymarin-loaded solid dispersion would be useful for the enhancement of oral bioavailability and hepatoprotective activity of poorly water-soluble silymarin.     

Flurbiprofen-loaded nanoparticles prepared with polyvinylpyrrolidone using Shirasu porous glass membranes and a spray-drying technique: nano-sized formation and improved bioavailability

A unique flurbiprofen-loaded nanoemulsion was listed earlier using a Shirasu porous glass (SPG) membrane emulsification technique, which gave constant emulsion droplets with a thin size distribution. In this study, a flurbiprofen-loaded nanoemulsion was developed further into a solid form using polyvinylpyrrolidone (PVP) as a carrier by a spray-drying technique. The flurbiprofen-loaded nanoparticles with a weight ratio of flurbiprofen/PVP/surfactant mixture of 1/8/2 were connected with about 130?000-fold enhanced drug solubility and had a mean size of about 70?nm. In these nanoparticles, flurbiprofen was found in an altered amorphous state. Additionally, the nanoparticles gave significantly shorter T_max, and greater AUC and C_max compared to the commercially available product. Specially, the AUC of the drug from the nanoparticles was about 10-fold greater compared to the commercially available product. Therefore, these flurbiprofen-loaded nanoparticles can be convenient for distributing a poorly water-soluble flurbiprofen with improved bioavailability using uniform nano-sized particles.     

Preparation of high solubilizable microemulsion of naproxen and its solubilization mechanism

With the aim of developing a novel valsartan-loaded solid dispersion with enhanced bioavailability and no crystalline changes, various valsartan-loaded solid dispersions were prepared with water, hydroxypropyl methylcellulose (HPMC) and sodium lauryl sulphate (SLS). Effects of the weight ratios of SLS/HPMC and carrier/drug on both the aqueous solubility of valsartan and the drug-release profiles of solid dispersions were investigated. The physicochemical properties of solid dispersions were characterized using scanning electron microscope (SEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The bioavailability of the solid dispersions in rats was evaluated compared to valsartan powder and a commercial product (Diovan). Unlike the conventional solid dispersion system, the valsartan-loaded solid dispersion had a relatively rough surface and did not change the crystalline form of the drug. It was suggested that the solid dispersions were formed by attaching hydrophilic carriers to the surface of the drug, thus changing from a hydrophobic to a hydrophilic form without changing the crystalline form. The drug-loaded solid dispersion composed of valsartan/HPMC/SLS at a weight ratio of 3/1.5/0.75 improved the drug solubility by about 43-fold. It gave a higher AUC, C(max) and shorter T(max) compared to valsartan powder and the commercial product. The solid dispersion improved the bioavailability of the drug in rats by about 2.2 and 1.7-fold in comparison with valsartan powder and the commercial product, respectively. Thus, the valsartan-loaded solid dispersion would be useful for delivering poorly water-soluble valsartan with enhanced bioavailability and no crystalline changes.     

A novel surface-attached carvedilol solid dispersion with enhanced solubility and dissolution

A novel surface-attached, spray-dried solid dispersion containing poorly water-soluble carvedilol (CV) without any change in the crystallinity was prepared using water, polyvinylpyrrolidone (PVP K30) and Tween 80. The solid dispersion was optimized by investigating the effects of the weight ratios of Tween 80/PVP K30 and carrier/drug on the aqueous solubility of CV. The optimum solid dispersion consisted of a relatively low carrier to drug weight ratio: the weight ratio of CV/PVP K30/Tween 80 was 12/4/2. Unlike conventional methods of solid dispersion preparation, this method yielded CV-loaded solid dispersion with no change in the crystallinity of the drug as was evident from SEM, DSC and XRD. It was demonstrated that the solid dispersions prepared had hydrophilic carriers attached to the surface of the drug, thus changing it from a hydrophobic to a hydrophilic form without changing the crystalline form. The optimized solid dispersion improved the drug solubility and dissolution rate by about 11,500-fold and twofold, respectively. It was further suggested that this method of solid dispersion preparation is better than conventional methods in terms of environmental and industrial standpoints. Thus, it was concluded that CV-loaded solid dispersion prepared using this method would be of use for delivering poorly water-soluble CV with enhanced solubility and dissolution, but without crystalline changes.     

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.     

Effects of solid carriers on the crystalline properties, dissolution and bioavailability of flurbiprofen in solid self-nanoemulsifying drug delivery system (solid SNEDDS)

In order to investigate the effects of solid carriers on the crystalline properties, dissolution and bioavailability of flurbiprofen in a solid self-nanoemulsifying drug delivery system (solid SNEDDS), different solid SNEDDS formulations were prepared by spray-drying the solutions containing liquid SNEDDS and various carriers. The liquid SNEDDS, composed of Labrafil M 1944 CS/Labrasol/Trasncutol HP (12.5/80/7.5%) with 2% w/v flurbiprofen, gave a z-average diameter of about 100 nm. Silicon dioxide, a hydrophobic solid carrier, produced an excellent conventional solid SNEDDS with a nanoemulsion droplet size of less than 100 nm, similar to the liquid SNEDDS and smaller than the other solid SNEDDS formulations. The drug was in an amorphous state in this solid SNEDDS. Furthermore, it greatly improved the dissolution rate and oral bioavailability of flurbiprofen in rats because it allowed the spontaneous formation of an interface between the oil droplets and the water. Magnesium stearate, a hydrophobic carrier, produced a solid SNEDDS with the largest diameter. However, it greatly enhanced the dissolution rate and oral bioavailability due to the formation of a simple eutectic mixture. The hydrophilic carriers such as polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (Na-CMC) and hydroxypropyl-β-cyclodextrantrin (HP-β-CD) did not form a solid SNEDDS but rather a solid dispersion (or microcapsule). HP-β-CD improved the dissolution rate but did not improve the oral bioavailability as much as the hydrophobic polymers. PVA and Na-CMC hardly improved the dissolution rate but maintained constantly high plasma levels in rats for a long period. Thus, the selection of carrier is an important factor in the development of solid SNEDDS, since the carriers had significant effects on the crystalline properties, dissolution and oral bioavailability of flurbiprofen and on the formation of solid SNEDDS.     

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.     

Preparation and evaluation of flurbiprofen-loaded microemulsion for parenteral delivery.

The purpose of this study was to improve the solubility of flurbiprofen, a poorly water-soluble drug, in an oil-in-water (o/w) microemulsion that is suitable for parenteral administration. Microemulsions with varying ratios of oil to surfactant were prepared with ethyl oleate, Tween 20 and isotonic solution. The effect of formulation variables on the particle size of microemulsion and solubility of flurbiprofen in microemulsion system was investigated. The pharmacokinetic parameters of flurbiprofen after intravenous administration of flurbiprofen-loaded microemulsion were compared with those of a solution of the drug. The mean droplet diameter of microemulsion containing less than 1% (w/w) of flurbiprofen was below 100 nm. The maximum solubility of flurbiprofen in the microemulsion system was found to be 10 mg/ml. However, the mean droplet diameters of flurbiprofen-loaded o/w microemulsions tend to be increased at room temperature. The pharmacokinetic parameters of flurbiprofen after intravenous administration of flurbiprofen-loaded microemulsion to rats were not significantly different from those of flurbiprofen in phosphate-buffered saline solution. It can be concluded that microemulsions of flurbiprofen prepared with ethyl oleate and Tween 20 can be used as a parenteral drug carrier for this and other poorly water-soluble drugs, provided that physical stability can be properly addressed. Copyright     

Development of novel ibuprofen-loaded solid dispersion with enhanced bioavailability using cycloamylose

To develop a novel ibuprofen-loaded solid dispersion with enhanced bioavailability using cycloamylose, it was prepared using spray-drying techniques with cycloamylose at a weight ratio of 1:1. The effect of cycloamylose on aqueous solubility of ibuprofen was investigated. The physicochemical properties of solid dispersions were investigated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction. The dissolution and bioavailability in rats were evaluated compared with ibuprofen powder. This ibuprofen-loaded solid dispersion improved about 14-fold drug solubility. Ibuprofen was present in an unchanged crystalline state, and cycloamylose played the simple role of a solubilizing agent in this solid dispersion. Moreover, the dispersion gave 2-fold higher AUC (area under the drug concentration-time curve) value compared with a ibuprofen powder, indicating that it improved the oral bioavailability of ibuprofen in rats. Thus, the solid dispersion may be useful to deliver ibuprofen with enhanced bioavailability without crystalline change.     

Development of novel flurbiprofen-loaded solid self-microemulsifying drug delivery system using gelatin as solid carrier

To develop a novel flurbiprofen-loaded solid self-microemulsifying drug delivery system (solid SMEDDS) with improved oral bioavailability using gelatin as a solid carrier, the solid SMEDDS formulation was prepared by spray-drying the solutions containing liquid SMEDDS and gelatin. The liquid SMEDDS, composed of Labrafil M 1944 CS/Labrasol/Transcutol HP (12.5/80/7.5%) with 2% w/v flurbiprofen, gave a z-average diameter of about 100?nm. The flurbiprofen-loaded solid SMEDDS formulation gave a larger emulsion droplet size compared to liquid SMEDDS. Unlike conventional solid SMEDDS, it produced a kind of microcapsule in which liquid SMEDDS was not absorbed onto the surfaces of carrier but formed together with carrier in it. However, the drug was in an amorphous state in it like conventional solid SMEDDS. It greatly improved the oral bioavailability of flurbiprofen in rats. Thus, gelatin could be used as a carrier in the development of solid SMEDDS with improved oral bioavailability of poorly water-soluble drug.     

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.     

Enhanced oral bioavailability of flurbiprofen by combined use of micelle solution and inclusion compound

The main purpose of this study was to evaluate the effect of a mixed drug solution containing a surfactant and β-cyclodextrin (β-CD) on the solubility and bioavailability of a poorly watersoluble drug, flurbiprofen. Solubility, dissolution and in vivo pharmacokinetics of flurbiprofen in the presence of surfactant, β-CD or mixture of surfactant and β-CD were investigated. Among the surfactants tested, Tween 80 produced the highest improvement in the aqueous solubility of flurbiprofen. The solubility of flurbiprofen increased linearly as a function of β-CD, resulting in B8 type that suggested a formation of inclusion complex in a molar ratio of 1:1. The solubility of flurbiprofen increased further when Tween 80 was included in addition to β-CD, suggesting that a micelle formation in the presence of Tween 80 was the likely reason for additional increase. Furthermore, the data suggested that Tween 80 did not interfere with the inclusion interaction between flurbiprofen and β-CD. The solubility of flurbiprofen was the highest in the mixed system containing 1.3 mM β-CD and 0.3% w/v Tween 80, and the maximum solubility of 160 μg/mL was achieved. Consistent with the enhanced solubility, the plasma exposure (both AUC and Cmax) of flurbiprofen when dosed as the mixed system was significantly higher (as much as 2 to 3-fold) than that without surfactant or β-CD, with surfactant alone, or with β-CD alone. Therefore, the mixed system consists of surfactant and β-CD could be used as an effective oral dosage form to improve bioavailability of poorly water soluble drugs such as flurbiprofen.     

Preparation and Evaluation of Fast Dissolving Ibuprofen-Polyethylene Glycol 6000 Solid Dispersions

To improve its oral absorption, rapidly dissolving ibuprofen solid dispersions (SD) were prepared in a relatively easy, simple, quick, inexpensive, and reproducible manner, characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). They were evaluated for solubility, in vitro release, and oral bioavailability of ibuprofen in rats. Loss of individual surface properties during melting and resolidification as revealed by SEM indicated the formation of effective SDs. Absence or shifting toward the lower melting temperature of the drug peak in SDs and physical mixtures in DSC study indicated the possibilities of drug-polymer interactions. However, no such interactions in the solid state were confirmed by FTIR spectra that showed the presence of drug crystalline in SDs. Quicker release of ibuprofen from SDs in rat intestine resulted in a significant increase in AUC and C_max, and a significant decrease in T_max over pure ibuprofen. Preliminary results from this study suggested that the preparation of fast-dissolving ibuprofen SDs by low temperature melting method using PEG 6000 as a meltable hydrophilic polymer carrier could be a promising approach to improve solubility, dissolution, and absorption rate of ibuprofen.     

非洛地平固体分散体的制备和体外溶出度考察

目的应用固体分散技术,提高非洛地平的体外溶出度。方法以PVPK30、Lutrol F68、Tween80(与吸附剂,如PVPP)为载体,分别采用溶剂法、熔融法、溶剂蒸发-沉积等技术制备非洛地平固体分散体,考察不同载体对固体分散体溶出度的影响。并着重考察以Tween 80为增溶剂,不同种类吸附剂为载体对固体分散体外观、溶出度的影响。应用差示热分析和X射线衍射鉴别药物在载体中的存在状态。结果采用不同载体和方法制备的非洛地平固体分散体均能明显促进药物的溶出,溶出速度依次为Tween 80>Lutrol F68>PVPk30。其中m(药物)∶m(Tween 80)∶m(PVPP)=1∶4∶5时,溶出速度最快,1 h累积释放率达90%以上。差示热分析固体分散体中药物吸热峰前移或消失,X射线衍射固体分散体中药物的结晶衍射峰消失,推测药物在载体中以无定形或分子形式存在。结论制备非洛地平固体分散体可以提高其体外溶出度,尤其是含有表面活性剂的固体分散体可进一步提高药物的溶出。     

Preparation and characterization of solid dispersions of Quercetin with PEG4000

Objective To enhance the solubility,quicken the speed of digesting and absorption,and increase the bioavailability of quercetin(3,3',4',5,7-pentahydroxyflavone).Methods A series of Quercetin-PEG4000 solid dispersions were prepared by fusion method.The configuration and property of solid dispersion were characterized by solubility tests,dissolution tests,FTIR spectra,differential scanning calorimetry(DSC)and microphotograph.Results 1.According to solubility tests the the mass ratio of quercetin to PEG4000 affected strongly on the solubility of solid dispersions,on the whole,the relation of the solubility of solid dispersions to the mass ratio presented linear relationship.The preparation temperature had little effect on the solubility of solid dispersions.The surface-active agent,polysorbate80 increased strongly the solubility of solid dispersions.2.According to the dissolution tests,the mass ratio of quercetin to PEG4000 affected strongly on the dissolution of solid dispersions,the preparation temperature had little effect on the dissolution of solid dispersions.The surface-active agent,polysorbate80 increased strongly the dissolution of solid dispersions,and after addition polysorbate80,the dissolution of solid dispersions was two times of the dissolution of solid dispersions without polysorbate80.3.According to the DSC results,except that a little of quercetin molecular existed as crystalline state in the solid dispersion with the mass ratio was qu:PEG=1:2,quercetin existed as amorphous phase in other mass ratio solid dispersion.4.According to the FTIR spectra and microphotograph results,the relation of quercetin and PEG4000 was mainly physical mixing in quercetin-PEG4000 solid dispersion.Quercetin was just like solute in solution,and PEG4000 was just like solvent in solution.The force between quercetin and PEG4000 was mainly hydrogen bonding,so the biological activity of quercetin would not be influenced greatly after the formation solid dispersion.Conclusions These results suggest that quercetin existed mainly as amorphous phase in solid dispersion;the solubility and the dissolution in water were increased obviously after formation the solid dispersion.     

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.     

New clopidogrel napadisilate salt and its solid dispersion with improved stability and bioequivalence to the commercial clopidogrel bisulphate salt in beagle dogs

The purpose of this study was to develop a novel clopidogrel napadisilate-loaded solid dispersion with improved stability and bioequivalence to the clopidogrel bisulphate-loaded commercial product. Clopidogrel napadisilate prepared in this study appeared as a white crystalline powder unlike clopidogrel base. However, this salt did not improve the solubility of clopidogrel, even with improved stability compared to clopidogrel bisulphate. To improve the solubility of clopidogrel napadisilate, a novel clopidogrel napadisilate-loaded solid dispersion was prepared by the spray-drying technique using HPMC and colloidal silica, and the physicochemical properties, dissolution and bioavailability in beagle dogs were evaluated compared to the clopidogrel bisulphate-loaded commercial product. The solid dispersion composed of clopidogrel napadisilate, HPMC and colloidal silica at a weight ratio of 11.069/3/3.5 improved solubility by 6.5-fold compared to clopidogrel napadisilate, even if it did not improve drug solubility compared to clopidogrel bisulphate. However, unlike clopidogrel bisulphate, this formulation improved the stability of clopidogrel. Furthermore, the clopidogrel napadisilate solid dispersion-loaded tablet showed similar dissolution to the clopidogrel bisulphate-loaded commercial product and was bioequivalent to the commercial product in beagle dogs. Thus, this clopidogrel napadisilate-loaded solid dispersion could be a promising candidate for improving the stability and bioavailability of clopidogrel.     

Improved dissolution behavior of lipophilic drugs by solid dispersions: the production process as starting point for formulation considerations

Introduction: Many new drug substances have low aqueous solubility which can cause poor bioavailability after oral administration. The application of solid dispersions is a useful method to increase the dissolution rate of these drugs and thereby improve their bioavailability. So far, several methods have been developed to prepare solid dispersions. To obtain a product with the desired attributes, both the formulation and production processes should be considered.

Areas covered: The most currently used methods to produce solid dispersions, such as the fusion method, hot melt extrusion, spray drying, freeze drying and supercritical fluid precipitation, are reviewed in this paper. In addition, the physicochemical characteristics of the obtained solid dispersions are discussed.

Expert opinion: Solid dispersions can be successfully prepared by simple fusion, hot melt extrusion, spray drying, freeze drying and supercritical fluid precipitation. Hot melt extrusion, spray drying and freeze drying are processes that can be applied for large scale production. The simple fusion method is not very suitable for large scale production, but is particularly suitable for screening formulations. The most recent method to produce sold dispersions is supercritical fluid precipitation. The process conditions of this method need extensive investigation, in particular in relationship with the selection of the type of carrier and/or solvent. Both processes and formulation aspects strongly affect the characteristics of solid dispersion products. Furthermore, application of crystalline solid dispersions is gaining increasing interest because they are thermodynamically more stable than amorphous solid dispersions.