Characteristics of Rofecoxib-Polyethylene Glycol 4000 Solid Dispersions and Tablets Based on Solid Dispersions

The aim of this work was to report the properties of rofecoxib-PEG 4000 solid dispersions and tablets prepared using rofecoxib solid dispersions. Rofecoxib is a poorly water soluble nonsteroidal anti-inflammatory drug with a poor dissolution profile. This work investigated the possibility of developing rofecoxib tablets, allowing fast, reproducible, and complete rofecoxib dissolution, by using rofecoxib solid dispersion in polyethylene glycol (PEG) 4000. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the solid state of solid dispersions. The effect of PEG 4000 concentration on the dissolution rate of rofecoxib from its solid dispersions was investigated. The dissolution rate of rofecoxib from its solid dispersions increased with an increasing amount of PEG 4000. The extent of dissolution rate enhancement was estimated by calculating the mean dissolution time (MDT) values. The MDT of rofecoxib decreased significantly after preparing its solid dispersions with PEG 4000. The FTIR spectroscopic studies showed the stability of rofecoxib and absence of well-defined rofecoxib-PEG 4000 interaction. The DSC and XRD studies indicated the amorphous state of rofecoxib in solid dispersions of rofecoxib with PEG 4000. SEM pictures showed the formation of effective solid dispersions of rofecoxib with PEG 4000 since well-defined change in the surface nature of rofecoxib and solid dispersions were observed. Solid dispersions formulation with highest drug dissolution rate (rofecoxib: PEG 4000 1:10 ratio) was used for the preparation of solid dispersion–based rofecoxib tablets by the direct compression method. Solid dispersion–based rofecoxib tablets obtained by direct compression, with a hardness of 8.1 Kp exhibited rapid drug dissolution and produced quick anti-inflammatory activity when compared to conventional tablets containing pure rofecoxib at the same drug dosage. This indicated that the improved dissolution rate and quick anti-inflammatory activity of rofecoxib can be obtained from its solid dispersion–based oral tablets.     

A calorimetric investigation into the interaction between paracetamol and polyethlene glycol 4000 in physical mixes and solid dispersions.

The solubility, heat of solution and dissolution rate of paracetamol and polyethyelene glycol 4000 (PEG 4000) systems have been studied in order to clarify the nature of the interaction between the two components during dissolution of solid dispersions. The logarithmic solubility of paracetamol demonstrated a non-linear increase with concentration of PEG 4000, while linear relationships between heat of solution in water and concentration were seen for both individual components. However, the heat of solution of paracetamol was found to decrease with increasing concentrations of PEG 4000. Similarly, the heats of solution in water of physical mixes and solid dispersions prepared using two manufacturing protocols were found to be lower than the theoretical values calculated from those corresponding to the individual components. Drug release studies showed a marked increase in paracetamol dissolution rate when prepared as a solid dispersion, with behaviour consistent with carrier controlled dissolution observed at low drug contents which was ascribed to enhanced dissolution of the drug into the diffusion layer of the PEG 4000. The implications of the understanding of this mechanism for the choice of carrier and manufacturing protocol for solid dispersion products is discussed.     

替硝唑固体分散体的制备及其体外释放特性研究

目的:利用固体分散技术制备替硝唑固体分散体,增加替硝唑溶解度和溶出速度。方法:以聚乙二醇(PEG)为载体材料,采用溶剂-熔融法制成固体分散体,测定表观溶解度,进行体外溶出试验,并采用差示扫描量热(DSC)法鉴别药物在固体分散体中的存在状态。结果:替硝唑的溶出度和表观溶解度随PEG的比例不同而不同,且溶出度随载体用量增加而增加。固体分散体的DSC曲线中替硝唑药物的特征熔融峰消失。结论:所制得的固体分散体能明显提高替硝唑的溶出度和表观溶解度。     

Characteristics of rofecoxib-polyethylene glycol 4000 solid dispersions and tablets based on solid dispersions

The aim of this work was to report the properties of rofecoxib-PEG 4000 solid dispersions and tablets prepared using rofecoxib solid dispersions. Rofecoxib is a poorly water soluble nonsteroidal anti-inflammatory drug with a poor dissolution profile. This work investigated the possibility of developing rofecoxib tablets, allowing fast, reproducible, and complete rofecoxib dissolution, by using rofecoxib solid dispersion in polyethylene glycol (PEG) 4000. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the solid state of solid dispersions. The effect of PEG 4000 concentration on the dissolution rate of rofecoxib from its solid dispersions was investigated. The dissolution rate of rofecoxib from its solid dispersions increased with an increasing amount of PEG 4000. The extent of dissolution rate enhancement was estimated by calculating the mean dissolution time (MDT) values. The MDT of rofecoxib decreased significantly after preparing its solid dispersions with PEG 4000. The FTIR spectroscopic studies showed the stability of rofecoxib and absence of well-defined rofecoxib-PEG 4000 interaction. The DSC and XRD studies indicated the amorphous state of rofecoxib in solid dispersions of rofecoxib with PEG 4000. SEM pictures showed the formation of effective solid dispersions of rofecoxib with PEG 4000 since well-defined change in the surface nature of rofecoxib and solid dispersions were observed. Solid dispersions formulation with highest drug dissolution rate (rofecoxib: PEG 4000 1:10 ratio) was used for the preparation of solid dispersion-based rofecoxib tablets by the direct compression method. Solid dispersion-based rofecoxib tablets obtained by direct compression, with a hardness of 8.1 Kp exhibited rapid drug dissolution and produced quick anti-inflammatory activity when compared to conventional tablets containing pure rofecoxib at the same drug dosage. This indicated that the improved dissolution rate and quick anti-inflammatory activity of rofecoxib can be obtained from its solid dispersion-based oral tablets.     

槲皮素-聚乙二醇固体分散体的研制

目的 制备槲皮素-聚乙二醇6000(PEG6000)固体分散体以提高槲皮素的水溶性。方法以PEG6000为载体,采用熔融法制备槲皮素的固体分散体,测定了槲皮素对照品、固体分散物以及机械混合物的溶解度,并通过红外光谱和紫外光谱对固体分散物进行了分析。结果槲皮素固体分散物的溶解度与槲皮素原料药和机械混合物相比有明显提高。结论槲皮素分子和载体分子之间未发生化学变化。     

Improvement of the dissolution kinetics of SR 33557 by means of solid dispersions containing PEG 6000

Solid dispersions of SR 33557 in preparations containing from 30 to 80% w/w polyethylene glycol 6000 (PEG 6000) were prepared by the fusion method. The solubility of the drug substance either alone or in solid dispersions was determined in pH 1.2 and 4.5 media (extraction fluid NFXII, without enzyme). A large increase in the solubility was noted from the 80% w/w PEG preparation. A wettability study performed by measuring the contact angle on tablets of either drug substance or PEG 6000, or solid dispersions, revealed a minimal contact angle for the 80% w/w PEG 6000 solid dispersion (eutectic composition of SR 33557/PEG 6000 phase diagram). Dissolution kinetic analysis performed at pH 1.2 on all solid dispersions, on the physical mixtures containing 70 and 80% w/w PEG 6000, and on SR 33557 alone, showed a maximum release rate (100%) for the solid dispersions containing 70 and 80% w/w PEG 6000. The dissolution rate of the physical mixtures was faster than that of the drug substance alone but remained, however, lower than that of the solid dispersions, at the same composition. It was also observed that the dissolution rate, at pH 1.2 and 4.5, of the 70% w/w PEG 6000 solid dispersion was practically pH independent, which was not the case for the drug substance alone. The latter solid dispersion showed a slowing down of the dissolution kinetics after 3 months storage at 50°C whereas no change in the dissolution rate was observed following storage for 12 months at 25°C.     

Experimental and mesoscale computational dynamics studies of the relationship between solubility and release of quercetin from PEG solid dispersions

The flavonol quercetin is potentially clinically relevant for its antimicrobial, beneficial cardiovascular effects, cancer treatment amongst others. However, its successful therapeutic application is severely curtailed by its poor water solubility and poor absorption following oral administration. In this study, solid dispersions of quercetin in poly(ethylene glycol) (PEG) at various compositions demonstrated an increase in the solubility, however with time, dissolution profiles show a decrease in dissolved flavonol concentration. The mechanism by which this decrease in solubility occurs was studied experimentally as well as by computational mesocscale particle dynamics simulations. The results suggest that phase separation of the polymer and flavonol during release from the solid dispersion is responsible for the time-dependent decrease in dissolved quercetin. It is suggested that the increase in release of quercetin in a PEG solid dispersion would only be beneficial if it were administered at the site of absorption, e.g. rectal administration, to ensure absorption prior to phase separation. The solid dispersions presented here would greatly improve the pharmaceutical availability of the flavonol at the site of absorption. Computational mesoscopic modeling was successfully applied to study the solid dispersions and corroborate experimental findings.     

Bioavailability enhancement of a poorly water-soluble drug by solid dispersion in polyethylene glycol-polysorbate 80 mixture

Oral bioavailability of a poorly water-soluble drug was greatly enhanced by using its solid dispersion in a surface-active carrier. The weakly basic drug (pK(a) approximately 5.5) had the highest solubility of 0.1mg/ml at pH 1.5, < 1 microg/ml aqueous solubility between pH 3.5 and 5.5 at 24+/-1 degrees C, and no detectable solubility (< 0.02 microg/ml) at pH greater than 5.5. Two solid dispersion formulations of the drug, one in Gelucire 44/14 and another one in a mixture of polyethylene glycol 3350 (PEG 3350) with polysorbate 80, were prepared by dissolving the drug in the molten carrier (65 degrees C) and filling the melt in hard gelatin capsules. From the two solid dispersion formulations, the PEG 3350-polysorbate 80 was selected for further development. The oral bioavailability of this formulation in dogs was compared with that of a capsule containing micronized drug blended with lactose and microcrystalline cellulose and a liquid solution in a mixture of PEG 400, polysorbate 80 and water. For intravenous administration, a solution in a mixture of propylene glycol, polysorbate 80 and water was used. Absolute oral bioavailability values from the capsule containing micronized drug, the capsule containing solid dispersion and the oral liquid were 1.7+/-1.0%, 35.8+/-5.2% and 59.6+/-21.4%, respectively. Thus, the solid dispersion provided a 21-fold increase in bioavailability of the drug as compared to the capsule containing micronized drug. A capsule formulation containing 25 mg of drug with a total fill weight of 600 mg was subsequently selected for further development. The selected solid dispersion formulation was physically and chemically stable under accelerated storage conditions for at least 6 months. It is hypothesized that polysorbate 80 ensures complete release of drug in a metastable finely dispersed state having a large surface area, which facilitates further solubilization by bile acids in the GI tract and the absorption into the enterocytes. Thus, the bioavailability of this poorly water-soluble drug was greatly enhanced by formulation as a solid dispersion in a surface-active carrier.     

Solid dispersion of meloxicam: factorially designed dosage form for geriatric population

The objective of the present work was to improve the dissolution properties of the poorly water-soluble drug meloxicam by preparing solid dispersions with hydroxyethyl cellulose (HEC), mannitol and polyethylene glycol (PEG) 4000 and to develop a dosage form for geriatric population. Differential scanning calorimetry, X-ray diffractometry, Fourier transform infrared spectroscopy and scanning electron microscopy were used to investigate the solid-state physical structure of the prepared solid dispersions. Higher in vitro dissolution of solid dispersions was recorded compared to their corresponding physical mixtures and the pure drug. PEG 4000 in 1: 9 drug to carrier ratio exhibited the highest drug release (100.2%), followed by mannitol (98.2%) and HEC (89.5%) in the same ratio. Meloxicam-PEG 4000 solid dispersion was formulated into suspension and optimization was carried out by 23 factorial design. Formulations containing higher levels of methyl cellulose and higher levels of either sodium citrate or Tween 80 exhibited the highest drug release.     

Physicochemical Characterization and Dissolution Study of Solid Dispersions of Lovastatin with Polyethylene Glycol 4000 and Polyvinylpyrrolidone K30

Solid dispersions in water-soluble carriers have attracted considerable interest as a means of improving the dissolution rate, and hence possibly bioavailability, of a range of hydrophobic drugs. The aim of the present study was to improve the solubility and dissolution rate of a poorly water-soluble drug, Lovastatin, by a solid dispersion technique. Solid dispersions were prepared by using polyethylene glycol 4000 (PEG 4000) and polyvinylpyrrolidone K30 (PVP K30) in different drug-to‐carrier ratios. Dispersions with PEG 4000 were prepared by fusion-cooling and solvent evaporation, whereas dispersions containing PVP K30 were prepared by solvent evaporation technique. These new formulations were characterized in the liquid state by phase solubility studies and in the solid state by differential scanning calorimetry, X-ray powder diffraction, and FT-IR spectroscopy. The aqueous solubility of Lovastatin was favored by the presence of both polymers. The negative values of the Gibbs free energy and enthalpy of transfer explained the spontaneous transfer from pure water to the aqueous polymer environment. Solid-state characterization indicated Lovastatin was present as amorphous material and entrapped in polymer matrix. In contrast to the very slow dissolution rate of pure Lovastatin, the dispersion of the drug in the polymers considerably enhanced the dissolution rate. This can be attributed to improved wettability and dispersibility, as well as decrease of the crystalline and increase of the amorphous fraction of the drug. Solid dispersion prepared with PVP showed the highest improvement in wettability and dissolution rate of Lovastatin. Even physical mixture of Lovastatin prepared with both polymers also showed better dissolution profile than that of pure Lovastatin. Tablets containing solid dispersion prepared with PEG and PVP showed significant improvement in the release profile of Lovastatin compared with tablets containing Lovastatin without PEG or PVP.     

Physicochemical characterization and dissolution study of solid dispersions of Lovastatin with polyethylene glycol 4000 and polyvinylpyrrolidone K30

Solid dispersions in water-soluble carriers have attracted considerable interest as a means of improving the dissolution rate, and hence possibly bioavailability, of a range of hydrophobic drugs. The aim of the present study was to improve the solubility and dissolution rate of a poorly water-soluble drug, Lovastatin, by a solid dispersion technique. Solid dispersions were prepared by using polyethylene glycol 4000 (PEG 4000) and polyvinylpyrrolidone K30 (PVP K30) in different drug-to-carrier ratios. Dispersions with PEG 4000 were prepared by fusion-cooling and solvent evaporation, whereas dispersions containing PVP K30 were prepared by solvent evaporation technique. These new formulations were characterized in the liquid state by phase solubility studies and in the solid state by differential scanning calorimetry, X-ray powder diffraction, and FT-IR spectroscopy. The aqueous solubility of Lovastatin was favored by the presence of both polymers. The negative values of the Gibbs free energy and enthalpy of transfer explained the spontaneous transfer from pure water to the aqueous polymer environment. Solid-state characterization indicated Lovastatin was present as amorphous material and entrapped in polymer matrix. In contrast to the very slow dissolution rate of pure Lovastatin, the dispersion of the drug in the polymers considerably enhanced the dissolution rate. This can be attributed to improved wettability and dispersibility, as well as decrease of the crystalline and increase of the amorphous fraction of the drug. Solid dispersion prepared with PVP showed the highest improvement in wettability and dissolution rate of Lovastatin. Even physical mixture of Lovastatin prepared with both polymers also showed better dissolution profile than that of pure Lovastatin. Tablets containing solid dispersion prepared with PEG and PVP showed significant improvement in the release profile Lovastatin compared with tablets containing Lovastatin without PEG or PVP.     

不同相对分子质量聚乙二醇对槲皮素的增溶作用

目的　研究不同相对分子质量聚乙二醇对槲皮素的增溶作用。方法　分别用聚乙二醇 4 0 0 0 ,6 0 0 0 ,10 0 0 0 (PEG40 0 0 ,PEG60 0 0 ,PEG10 0 0 0 )为载体 ,采用熔融法制备槲皮素固体分散体 ,测定槲皮素原料药、固体分散物以及机械混合物的溶解度 ,以红外光谱和紫外光谱分析固体分散物。结果　槲皮素固体分散物中槲皮素的溶解度 (48.78,78.39,81.35 mg.L-1)比槲皮素 (12 .75 mg.L-1)以及相同质量比机械混合物 (12 .86 ,13.15 ,13.2 8mg.L-1)的溶解度有明显提高。结论　不同相对分子量聚乙二醇可以不同程度增加槲皮素的溶解度。     

磷脂固体分散体对槲皮素溶出促进作用的研究

目的研究磷脂固体分散体对槲皮素溶出的促进作用。方法用溶剂法制备了不同比例的槲皮素的磷脂固体分散体 ,与其相应的物理混合物及槲皮素的PVP或PEG4 0 0 0 (1∶1)固体分散体并进行了溶出的对比研究。结果所制得固体分散体均可改善槲皮素的溶出 ,而质量比为 1∶1的槲皮素 磷脂固体分散体的溶出促进作用最为显著。DSC和X射线粉末衍射的研究表明 ,在质量比为1∶1的槲皮素 磷脂固体分散体中 ,槲皮素以无定形的状态分散于载体磷脂中 ,其熔点吸热峰消失。结论槲皮素溶出度的增大与其无定形的存在状态、磷脂对其的润湿作用以及磷脂在水中可形成脂质体有关     

Physicochemical characterization and in vivo properties of Zolpidem in solid dispersions with polyethylene glycol 4000 and 6000.

Solid dispersions and physical mixtures of Zolpidem in polyethylene glycol 4000 (PEG 4000) and 6000 (PEG 6000) were prepared with the aim to increase its aqueous solubility. These PEG based formulations of the drug were characterized in solid state by FT-IR spectroscopy, X-ray powder diffraction, and differential scanning calorimetry. By these physical determinations no drug-polymer interactions were evidenced. Both solubility and dissolution rate of the drug in these formulations were increased. Each individual dissolution profile of PEG based formulation fitted Baker-Lonsdale and first order kinetic models. Finally, significant differences in ataxic induction time were observed between Zolpidem orally administered as suspension of drug alone and as solid dispersion or physical mixture. These formulations, indeed, showed almost two- to three-fold longer ataxic induction times suggesting that, in the presence of PEG, the intestinal membrane permeability is probably the rate-limiting factor of the absorption process. Copyright     

槲皮素PVP固体分散体的制备及物相鉴定

目的用溶剂法制备槲皮素-PVP固体分散体并考察其溶出特性并对物相进行鉴定。方法采用溶剂法制备槲皮素-PVP固体分散体,通过溶出实验对槲皮素溶出率的测定研究固体分散体的溶出性质,利用差热分析（Differentialscanning calorimetry,DSC）、红外光谱分析（Infrared spectroscopy,IR）、粉末X衍射（X-ray powder diffractometry,PXRD）、扫描电镜（Scanning electron microscopy,SEM）等方法对其进行物相鉴定。结果槲皮素-PVP固体分散体的溶出速率相对其物理混合物有了明显的改善; 溶解实验显示固体分散体中槲皮素的溶解度有了显著的提高;热差分析及粉末X衍射结果表明固体分散体中槲皮素呈非结晶形式;扫描电镜下固体分散体中无槲皮素晶体。结论采用溶剂法制备槲皮素-PVP固体分散体可显著提高槲皮素的溶解度及溶出速度。     

Preparation of esomeprazole zinc solid dispersion and study on its pharmacokinetics

Esomeprazole zinc (EZ) is a poorly water-soluble substance. In order to increase its dissolution rate and bioavailability, solid dispersions of esomeprazole zinc (SDEZ) in polyethylene glycol 4000 (PEG4000) with different EZ to PEG4000 ratios were prepared by solvent method. Our studies showed that dissolution rate of EZ were distinctively increased in the solid dispersion system compared to that in pure EZ or physical mixtures. The increase of dissolution rate was obviously related to the ratio of EZ to PEG4000. The solid dispersion system (EZ/PEG4000=1/8, w/w) gave the highest dissolution rate: about 14.7-fold higher than that of the pure EZ. EZ was proved to be in amorphous state in this solid dispersion by using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) techniques. In vivo administration studies, SDEZ in enteric capsule (SDEZ-EC) has a lower Cmax and a longer Tmax than that of esomeprazole magnesium enteric-coated tablet (Nexium), and the differences of Cmax and Tmax between SDEZ-EC and Nexium are significant. This result suggests SDEZ-EC has a lower absorption rate than Nexium and corresponds with the in vitro dissolution.     

布格呋喃固体分散体的体外研究

布格呋喃(buagafuran,AF-5)是以( )香芹酮为起始原料通过立体选择性合成的沉香呋喃类化合物[1].它具有显著的抗焦虑作用,毒副作用低,市场前景广阔.布格呋喃为油状液体,脂溶性强,不溶于水.用植物油稀释进行小鼠灌胃,抗焦虑活性与空白组比较无统计学意义,不能较好地发挥药效.室温放置易发生降解,化学稳定性差.这些缺     

硝苯地平固体分散体制备工艺的研究

目的利用固体分散技术将硝苯地平制成固体分散体,提高其体外溶出速率。方法分别以聚乙二醇6000(PEG6000)、聚乙二醇4000(PEG4000)、聚乙烯吡咯烷酮K30(PVPK30)、泊洛沙姆188(Pluronic F68)等为载体,用熔融法、溶剂法、溶剂-熔融法和喷雾干燥法制备硝苯地平固体分散体。采用差热分析法(DTA)分析药物在固体分散体中的存在状态,并进行体外溶出度试验。结果各种固体分散体均能加快药物的溶出速率,并且随着载体在固体分散体中的比例增大,溶出速率增大。DTA分析显示硝苯地平在PVPK30的固体分散体中以微细结晶存在。结论将硝苯地平制成固体分散体能显著提高硝苯地平的体外溶出速率。     

Relating solubility data of parabens in liquid PEG 400 to the behaviour of PEG 4000-parabens solid dispersions

The solid state behaviour of polyethylene glycol 4000 (PEG 4000) and dispersions of a homologous series of parabens (methyl- (MP), ethyl- (EP), propyl- (PP) and butyl- (BP)) were examined and compared to the paraben solubility in liquid PEG 400. Dispersions were prepared by co-melting different amounts of paraben (5–80% (w/w)) and PEG 4000 and were studied using a combination of differential scanning calorimetry (DSC) and small and wide angle X-ray diffraction (SAXD/WAXD). Depending on the concentration of parabens in the dispersions, DSC showed melting peaks from folded and unfolded forms of PEG, a eutectic melting and melting of pure parabens. The fraction of folded PEG increased and the melting temperatures of both PEG forms decreased with increasing paraben content. In an apparent phase diagram of PP–PEG dispersions a eutectic mixture appeared above 5% PP. In addition, a melting peak corresponding to the paraben appeared for dispersion containing more than 60% PP. Similar phase diagrams were shown for the other parabens. The SAXD data and a 1D correlation function analysis revealed that MP and BP were incorporated into the amorphous domains of the lamellae of solid PEG to a higher degree than EP and PP. In addition, the lamellae thickness of PEG and the fraction of amorphous domains increased more for MP and BP compared to EP and PP. BP showed the highest solubility of the parabens followed by MP, EP and PP in both liquid and solid PEG. Furthermore, the thickness of the amorphous domains of the PEG in the different parabens–PEG dispersions could be correlated to the solubility in liquid PEG 400.     

Physicochemical characterization and dissolution of norfloxacin/cyclodextrin inclusion compounds and PEG solid dispersions

Increase in the poor water solubility and dissolution rate of norfloxacin was studied. Two systems were used: solid dispersion with PEG 6000 prepared using the fusion method and inclusion complexes with cyclodextrins (β-cyclodextrin and HP-β-cyclodextrin) obtained by freeze-drying. IR spectrophotometry, X-ray diffractometry, and differential scanning calorimetry showed differences between norfloxacin/cyclodextrin complexes and their corresponding physical mixtures, but not between norfloxacin/PEG 6000 solid dispersions and their corresponding physical mixtures. The solubility and dissolution rate of norfloxacin were significantly increased with PEG solid dispersions and cyclodextrin complexes as well as with norfloxacin-CD physical mixtures. However, enhancement was not statistically different either among various cyclodextrin complexes, or between solid dispersions and cyclodextrin complexes.