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.     

In vitro and in vivo evaluation of carbamazepine-PEG 6000 solid dispersions

The present work extended previous physico-chemical investigations on the effects of solid dispersion on the solubility, the dissolution rate and the pharmacokinetic profile of carbamazepine. Solubility studies showed a linear increase in carbamazepine solubility with the increase of PEG 6000 concentration. There is no marked difference between physical mixtures and solid dispersions for the enhancement of carbamazepine solubility by PEG 6000. Less than 60% of pure carbamazepine was dissolved in 90 min. Physical mixtures (carbamazepine phase III) and solid dispersions (carbamazepine phase II) dissolution rates were higher in comparison of the parent drug. The dissolution of carbamazepine phase III was more pronounced than that evoked by the phase II. The dissolution profiles indicated that the percentage of the drug dissolved was dependent on the proportion of PEG 6000. In solid dispersions there was a remarkable enhancement in the dissolution rates of the drug in the vicinity of the eutectic composition as compared with those of corresponding physical mixtures. Hence, the optimum value for the solid dispersion was 80.5+/-1.7% of carbamazepine having dissolved within the first 10 min compared to 40+/-1% for the corresponding physical mixtures of the same composition. Statistical analysis of pharmacokinetic parameters confirmed that the carbamazepine:PEG 6000 binary systems displayed higher bioavailability of the drug than the pure carbamazepine. The area under the curve (AUC) values highlighted the evidence that only slight differences in the bioavailability of the drug occur between physical mixtures and solid dispersions prepared at the 80:20 and 50:50 drug:carrier compositions. However, the mean normalized plasma concentrations showed that standard error deviations are rather wide intervals for pure drug and physical mixtures in comparison to solid dispersions. One additional interesting point to consider is the disappearance of the multiple peaks on the individual kinetic curves of the 50:50 solid dispersion composition. Furthermore, our investigations have highlighted the interest of solid dispersions prepared at -eutectic composition as our preliminary data show that the plasma concentration (C(5h)) of the drug for the 15:85 dispersed sample containing 150 mg of carbamazepine is not significantly different from that obtained for the 50:50 dispersed sample containing 300 mg of the drug.     

Mechanism of increased dissolution of diazepam and temazepam from polyethylene glycol 6000 solid dispersions

Solid dispersion literature, describing the mechanism of dissolution of drug-polyethylene glycol dispersions, still shows some gaps; (A). only few studies include experiments evaluating solid solution formation and the particle size of the drug in the dispersion particles, two factors that can have a profound effect on the dissolution. (B). Solid dispersion preparation involves a recrystallisation process (which is known to be highly sensitive to the recrystallisation conditions) of polyethylene glycol and possibly also of the drug. Therefore, it is of extreme importance that all experiments are performed on dispersion aliquots, which can be believed to be physico-chemical identical. This is not always the case. (C). Polyethylene glycol 6000 (PEG6000) crystallises forming lamellae with chains either fully extended or folded once or twice depending on the crystallisation conditions. Recently, a high resolution differential scanning calorimetry (DSC)-method, capable of evaluating qualitatively and quantitatively the polymorphic behaviour of PEG6000, has been reported. Unraveling the relationship between the polymorphic behavior of PEG6000 in a solid dispersion and the dissolution characteristics of that dispersion, is a real gain to our knowledge of solid dispersions, since this has never been thoroughly investigated. The aim of the present study was to fill up the three above mentioned gaps in solid dispersion literature. Therefore, physical mixtures and solid dispersions were prepared and in order to unravel the relationship between their physico-chemical properties and dissolution characteristics, pure drugs (diazepam, temazepam), polymer (PEG6000), solid dispersions and physical mixtures were characterised by DSC, X-ray powder diffraction (Guinier and Bragg-Brentano method), FT-IR spectroscopy, dissolution and solubility experiments and the particle size of the drug in the dispersion particles was estimated using a newly developed method. Addition of PEG6000 improves the dissolution rate of both drugs. Mechanisms involved are solubilisation and improved wetting of the drug in the polyethylene glycol rich micro-environment formed at the surface of drug crystals after dissolution of the polymer. Formulation of solid dispersions did not further improve the dissolution rate compared with physical mixtures. X-ray spectra show that both drugs are in a highly crystalline state in the solid dispersions, while no significant changes in the lattice spacings of PEG6000 indicate the absence of solid solution formation. IR spectra show the absence of a hydrogen bonding interaction between the benzodiazepines and PEG6000. Furthermore, it was concluded that the reduction of the mean drug particle size by preparing solid dispersions with PEG6000 is limited and that the influence of the polymorphic behavior of PEG6000 (as observed by DSC) on the dissolution was negligible.     

格列喹酮固体分散体的制备及溶出度测定

目的:制备格列喹酮固体分散体并考察其体外溶出性。方法:以聚乙烯吡咯烷酮K30(PVP)、聚乙二醇6000(PEG)为载体,溶剂熔融法和溶剂法制备格列喹酮固体分散体,并与原料药比较体外溶出度。结果:载体比例越大,药物溶出愈快。载体为PVP所制固体分散体的体外溶出行为总体优于载体为PEG者。格列喹酮-PVP固体分散体(1∶7)10min内体外溶出度达到70%以上,优于格列喹酮原料药。结论:成功制备了格列喹酮固体分散体。     

The properties of solid dispersions of indomethacin or phenylbutazone in polyethylene glycol

The effects of molecular weight of polyethylene glyeols (PEGs) on the dissolution rates and crystallinity of its solid dispersions with indoniethacin and phenylbutazone have been examined. The dissolution rates of both solid-dispersed drugs decreased as the molecular weight of PEG increased. The indoniethacin dissolution profiles were essentially linear using constant surface area disc methodology and a limiting dissolution rate of about 10.6 mg · min⁻¹ was observed. The phenylbutazone dissolution profiles were. however, generally linear-curvic usually giving lower release rates than the comparative indomethacin weight fractions. A limiting dissolution rate for the linear portions of the profiles was about 1.8 mg · min⁻¹. Infra-red spectra indicated that the differences between the two drugs could partly be explained on the basis of PEG crystallinity. Generally bands in the ranges 1100–1130 and 1200–1400 cm⁻¹ were poorly differentiated in indomethacin dispersions (PEG 1500, PEG 4000 and PEG 6000) but were better differentiated in phenylbutazone dispersions (PEG 4000, PEG 6000 and PEG 20,000). A greater proportion of amorphousness within the PEG moiety was predicted in indomethacin dispersions by the appearance of a new weak band at 1326 cm⁻¹ and by a decrease in intensity of the band at 845 cm⁻¹ at the expense of the peak at 960 cm⁻¹. The evidence was supported by differential scanning calorimetry. The heats of fusion were 44.7, 46.4, 47.2 and 39.5 cal · g⁻¹ for PEG 1500, PEG 4000, PEG 6000 and PEG 20.000 respectively. Heats of fusion for indomethacin dispersions (2, 5 and 10% drug) were generally lower than for the corresponding values for phenylbutazone dispersions-with the exception of PEG 20,000 dispersions. For example, values were obtained of 30.6 and 37.9 cal · g⁻¹ for PEG 1500 dispersions containing 10% indomethacin and phenylbutazone, respectively.     

缬沙坦固体分散体的制备及体外溶出度研究

目的采用冷冻干燥法制备缬沙坦（Valsartan）速释固体分散体（SD）来提高其体外溶出度。方法分别以羟丙甲基纤维素（HPMC）、聚乙二醇6000（PEG6000）、聚乙烯吡咯烷酮k30（PVPk30）为载体,十二烷基硫酸钠（SDS）为表面活性剂来制备不同比例的缬沙坦固体分散体,通过测定体外溶出度,来选择最优辅料及比例,结果当以PEG6000载体,SDS为表面活性剂时,且药物：PEG6000：SDS=1：5：1％时药物呈现了很好的水溶性。结论在5min时即可溶出90％以上,很大程度上提高了缬沙坦的体外溶出度。     

Physical Stability of Solid Dispersions Containing Triamterene or Temazepam in Polyethylene Glycols

The effect of storage on the physical stability of solid dispersions of triamterene or temazepam in polyethylene glycols was studied using differential scanning calorimetry (DSC), particle-size analysis and dissolution methods. The enthalpies of fusion of the carriers, without included drug and previously fused and crystallized, increased on storage. Analysis of similarly treated solid dispersions, containing either 10% temazepam or 10% triamterene, showed that each drug influenced the morphology of the polyethylene glycol (PEG). The enthalpies and melting points of the solidus components of the dispersions' carriers were initially reduced after preparation, but on storage these increased. The particle sizes of the drugs dispersed in the PEGs increased on storage. The changes in dissolution after storage of triamterene or temazepam dispersions were smaller for dispersions in PEG 1500 than for dispersions in PEGs of higher molecular weight (PEG 2000, PEG 4000 or PEG 6000) in which the reduction in dissolution was particularly marked during the first month of storage. The rank order of changes in dissolution were PEG 1500 ? PEG 2000 < PEG 4000 ～ PEG 6000.     

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.     

Characterization of ternary solid dispersions of itraconazole, PEG 6000, and HPMC 2910 E5

In order to reduce the crystallinity of PEG 6000, blends were prepared by spray drying and extrusion with the following polymers; PVP K25, PVPVA 64, and HPMC 2910 E5. The maximal reduction of crystallinity in PEG 6000 was obtained by co-spray drying with HPMC 2910 E5. In the next step the model drug Itraconazole was added to the blend and the resulting ternary solid dispersions were characterized. The results of this study show that the addition of PEG 6000 to the Itraconazole/HPMC 2910 E5 system leads to phase separation that in most cases gives rise to recrystallization of either PEG 6000 or Itraconazole. For all ternary dispersions containing 20% of Itraconazole the drug was highly amorphous and the dissolution was improved compared to the binary 20/80 w/w Itraconazole/HPMC 2910 E5 solid dispersion. For all ternary dispersions containing 40% of Itraconazole, the drug was partially crystalline and the dissolution was lower than the dissolution of the binary 40/60 w/w Itraconazole/HPMC 2910 E5 dispersion. These results show that provided Itraconazole is highly amorphous the addition of PEG 6000 to HPMC 2910 E5 leads to an increase in drug release.     

A comparative study on the effects of amphiphilic and hydrophilic polymers on the release profiles of a poorly water-soluble drug

This paper reports the use of two crystalline polymers, an amphiphilic Pluronic® F-127 (PF-127) and a hydrophilic poly(ethylene glycol) (PEG6000) as drug delivery carriers for improving the drug release of a poorly water-soluble drug, fenofibrate (FEN), via micelle formation and formation of a solid dispersion (SD). In 10% PF-127 (aq.), FEN showed an equilibrium solubility of ca. 0.6?mg/mL, due to micelle formation. In contrast, in 10% PEG6000 (aq.), FEN only exhibited an equilibrium solubility of 0.0037?mg/mL. FEN-loaded micelles in PF-127 were prepared by direct dissolution and membrane dialysis. Both methods only yielded a highest drug loading (DL) of 0.5%. SDs of FEN in PF-127 and PEG6000, at DLs of 5–80%, were prepared by solvent evaporation. In-vitro dissolution testing showed that both micelles and SDs significantly improved FEN’s release rate. The SDs of FEN in PF-127 showed significantly faster release than crystalline FEN, when the DL was as high as 50%, whereas SDs of PEG6000 showed similar enhancement in the release rate when the DL was not more than 20%. The DSC thermograms of SDs of PF-127 exhibited a single phase transition peak at ca. 55–57?°C when the DL was not more than 50%, whereas those in PEG6000 exhibited a similar peak at ca. 61–63?°C when the DL was not more than 35%. When the DL exceeded 50% for SDs of PF-127 and 35% for SDs of PEG6000, DSC thermograms showed two melting peaks for the carrier polymer and FEN, respectively. FT-IR studies revealed that PF-127 has a stronger hydrophobic–hydrophobic interaction with FEN than PEG6000. It is likely that both dispersion and micelle formation contributed to the stronger effect of PF-127 on enhancing the release rate of FEN in its SDs.     

Physical stability of solid dispersions of the antiviral agent UC-781 with PEG 6000, Gelucire 44/14 and PVP K30

This paper describes the physical stability of solid dispersions of UC-781 with PEG 6000, Gelucire 44/14 and PVP K30 prepared by the solvent and melting methods. The concentration of the drug in the solid dispersions ranged from 5 to 80% w/w. The solid dispersions were stored at 4-8 and 25 degrees C (25% RH), then their physicochemical properties were analysed by differential scanning calorimetry (DSC), X-ray powder diffraction and dissolution studies as a function of storage time. The DSC curves of solid dispersions of UC-781 with PVP K30 did not show any melting peaks corresponding to UC-781 after storage, indicating no recrystallization of the drug. The DSC data obtained from PEG 6000 and Gelucire 44/14 showed some variations in melting peak temperatures and enthalpy of fusion of the carriers. It was shown that the enthalpy of fusion of PEG 6000 in the dispersions increased after storage; it was more pronounced for samples stored at 25 degrees C compared to those at 4-8 degrees C indicating the reorganization of the crystalline domains of the polymer. Similarly, the enthalpy of fusion of Gelucire 44/14 in the solid dispersions increased as a function of time. Dissolution of UC-781 from all solid dispersions decreased as a function of storage time. While these observations concurred with the DSC data for all solid dispersions, they were not reflected by X-ray powder diffraction data. It was concluded that it is the change of the physical state of the carriers and not that of the drug, which is responsible for the decreased dissolution properties of the solid dispersions investigated.     

Influence of polyethylene glycol 6000 and mannitol on the in-vitro dissolution properties of nitrofurantoin by the dispersion technique

Employing the dispersion technique the influence of mannitol and polyethylene glycol (PEG) 6000 on the in-vitro dissolution of nitrofurantoin was investigated. Dispersions of the drug with PEG 6000 showed faster dissolution rates when compared with dispersions of the drug in mannitol. Tablet formulation of the drug--PEG 6000 dispersion exhibited better drug releasing properties as compared to tablets prepared from the drug's PEG 6000 physical mixture, or the drug's formulation with Avicel PH 101.     

热熔挤出技术制备吡罗昔康固体分散体

目的采用热熔挤出技术制备难溶性药物吡罗昔康固体分散体,来提高其溶出速率。方法以共聚维酮(PVP-VA64)为亲水性载体材料,聚乙二醇6000为增塑剂,采用热熔挤出技术制备吡罗昔康固体分散体。通过比较差示扫描量热图谱和累积溶出曲线,来表征和评价所制备的固体分散体。结果所制备的固体分散体溶出速率较物理混合物均显著提高。结论热熔挤出技术适用于制备吡罗昔康固体分散体,药物是以无定型分散在载体中,溶出度得到显著提高。     

布渣叶总黄酮固体分散体的制备及体外溶出度测定

目的:采用固体分散体技术考察不同载体材料对布渣叶总黄酮提取物溶出度的影响.方法:选择不同种类的聚乙二醇、泊洛沙姆、聚乙烯吡咯烷酮为载体材料,与布渣叶总黄酮提取物按质量比1:4混合均匀,分别用熔融法和溶剂法制备固体分散体,以固体分散体中总黄酮、牡荆苷、异牡荆苷、水仙苷的90 min累积溶出度作为评价指标,比较不同载体制备的固体分散体的释药速率,并采用X射线衍射和红外光谱分析对其物相特征进行研究.结果:与布渣叶总黄酮提取物和物理混合物相比,以PEG和泊洛沙姆所制备的布渣叶提取物固体分散体中总黄酮、牡荆苷、异牡荆苷和水仙苷的体外溶出度与溶出速率均明显增加.其中以泊洛沙姆407为载体材料所制备的固体分散体中总黄酮体外溶出度最佳,90 min累积溶出度达到84%;以PEG 6000为载体材料所制备的固体分散体中牡荆苷、异牡荆苷、水仙苷体外溶出度最佳,90 min累积溶出度均达96%以上.结论:采用固体分散体技术,选择PEG 6000或泊洛沙姆407为载体制备布渣叶总黄酮提取物固体分散体,对提取物中脂溶性成分的溶出有明显改善作用.     

Solid dispersion adsorbates for enhancement of dissolution rates of drugs

Amalgamation of solid dispersion and melt adsorption technologies was utilized for enhancing the dissolution rate of poorly soluble drugs. Glibenclamide was employed as a model drug. PEG6000 and Gelucire44/14 were used as hydrophilic carriers for the preparation of solid dispersions, and lactose was utilized as an adsorbent for the preparation of solid dispersion adsorbates. A high dissolution rate of solid dispersion adsorbates was observed when compared to solid dispersions alone and one of the marketed products.     

尼莫地平固体分散物的制备及其片剂溶出度的研究

目的：提高难溶性药物尼莫地平的溶出速率。方法：选用PVP－k30和PEG6000为载体制备了不同晶型尼莫地平固体分散物和机械混合物，比较了它们片剂体外的溶出速率。结果：尼莫地平固体分散物的片剂溶出度高于机械混合物的，低熔点机械混合物片剂溶出度高于高熔点的，不同晶型尼莫地平PEG6000固体分散物片剂体外的溶出速率无显著性差异，低熔点尼莫地平PVK－k30固体分散物的片剂的90min累积溶出量比高熔点的高。结论：不同晶型尼莫地平制备成PVP-k30和PEG6000固体分散物都可以提高其片剂体外的溶出度。     

茶碱脉冲栓剂的制备及体外释药性考察

目的:制备茶碱脉冲栓剂并评价其体外释药性质。方法:以处方基质中泊洛沙姆、羧甲基纤维素钠(CMC-Na)、聚乙二醇6000(PEG6000)、PEG400的不同用量为因素,以释药时滞及累积释药率为指标采用单因素法筛选栓剂处方组成,并考察填充不同内容物(茶碱原料、茶碱-PVP物理混合物和茶碱-PVP固体分散体)的栓剂的累积释药率。结果:较优基质处方组成为70%泊洛沙姆、6%CMC-Na、12%PEG6000、12%PEG400,其体外释药时滞为4h,90min累积释药率为85%以上;3种填充不同内容物的栓剂累积释药率分别为58.8%、65.8%、91%。结论:所制茶碱脉冲栓剂具有较好的脉冲释药作用。     

RP—HPLC法测定布洛芬-聚乙二醇6000固体分散体中布洛芬的含量

目的 建立反相高效液相色谱法测定布洛芬-聚乙二醇6000固体分散体中布洛芬的含量.方法 色谱柱为Shimadzu C18柱,流动相为0.02 mol·L^-1醋酸钠（冰醋酸调节pH至3.0±0.1）-乙腈（40：60）,流速1.0ml·min^-1,检测波长为264nm,进样量为20μl.结果 布洛芬质量浓度在0.051～1.02 mg·ml^-1范围内与相应峰面积呈良好线性关系（r=0.999 9,n=6）,平均加样回收率为98.40%,RSD为0.92%（n=9）.结论 所用方法准确、简便、快速,适用于布洛芬-聚乙二醇6000固体分散体中布洛芬的含量测定.     

In vivo and in vitro evaluation of a solid dispersion system of gliclazide:PEG 6000

OBJECTIVE: Gliclazide is a potent antidiabetic agent because of its capability to decrease blood glucose level via stimulating endogenous insulin secretion from beta-pancreas cells. Gliclazide is insoluble in water and has low dissolution rate. In this study, polyethylene glycol (PEG) 6000 was used as a matrix to disperse gliclazide in the solid state, and the pharmacokinetic profile of this solid dispersion was studied in rats. DESIGN: The solid dispersion of Gliclazide:PEG 6000 (1:4) was prepared by solvent evaporation method. MAIN OUTCOME MEASURES: Samples characterization included differential scanning calorimetry (DSC), infrared spectroscopy (IR), X-ray diffraction (XRD), and solubility and dissolution test. In vivo study was carried out in healthy rats, randomly. After a single dose of oral administration, blood samples were collected pre-dose (15 min before) and 1, 2, 3, 4, 5, 6, 8, 10, and 12 h post-dose. Plasma concentration of gliclazide was determined by high pressure liquid chromatography method using C-18 column, with mobile phase KH2PO4 (pH 4.6)-acetonitril (40:60 v/v) and UV detection at 229 nm. RESULTS: Results showed that there were no differences in DSC, IR spectroscopy, XRD, and dissolution test between the solid dispersion and physical mixture. In vivo data showed that the Tmax of gliclazide in solid dispersion and physical mixture was significantly decreased, while the Cmax, AUC(0-12), and AUC(0-infinity) were significantly increased compared to gliclazide alone. These results indicate that the rapid Tmax was due to rapid absorption of gliclazid across the GI tract membrane. Increased Cmax, AUC(0-12), and AUC(0-infinity) indicate a better absorption of gliclazide in solid dispersion and physical mixture than of gliclazide alone. CONCLUSION: Increased in gliclazide dissolution in the presence of PEG 6000 was followed by improved in vivo data.     

Physicochemical characterization of solid dispersions of the antiviral agent UC-781 with polyethylene glycol 6000 and Gelucire 44/14

The purpose of this study was to prepare and characterize solid dispersions of the antiviral thiocarboxanilide UC-781 with PEG 6000 and Gelucire 44/14 with the intention of improving its dissolution properties. The solid dispersions were prepared by the fusion method. Evaluation of the properties of the dispersions was performed using dissolution studies, differential scanning calorimetry, Fourier-transform infrared spectroscopy and X-ray powder diffraction. To investigate the possible formation of solid solutions of the drug in the carriers, the lattice spacings [d] of PEG 6000 and Gelucire 44/14 were determined in different concentrations of UC-781. The results obtained showed that the rate of dissolution of UC-781 was considerably improved when formulated in solid dispersions with PEG 6000 and Gelucire 44/14 as compared to pure UC-781. From the phase diagrams of PEG 6000 and Gelucire 44/14 it could be noted that up to approximately 25% w/w of the drug was dissolved in the liquid phase in the case of PEG 6000 and Gelucire 44/14. The data from the X-ray diffraction showed that the drug was still detectable in the solid state below a concentration of 5% w/w in the presence of PEG 6000 and Gelucire 44/14, while no significant changes in the lattice spacings of PEG 6000 or Gelucire 44/14 were observed. Therefore, the possibility of UC-781 to form solid solutions with the carriers under investigation was ruled out. The results from infrared spectroscopy together with those from X-ray diffraction and differential scanning calorimetry showed the absence of well-defined drug–polymer interactions.