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.     

Enhanced release of solid dispersions of etodolac in polyethylene glycol

This work examines the release of etodolac from various molecular weight fractions of polyethylene glycol (PEG) solid dispersions. Solid dispersions of etodolac were prepared in different molar ratios of drug/carrier by using solvent and melting methods. The release rate of etodolac from the resulting complexes was determined from dissolution studies by use of USP dissolution apparatus 2 (paddle method). The physical state and drug:PEG interaction of solid dispersions and physical mixtures were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR) and differential scanning calorimetry (DSC). The dissolution rate of etodolac is increased in all of the solid dispersion systems compared to that of the pure drug and physical mixtures. The solid dispersion compound prepared in the molar ratio of 1:5 by the solvent method was found to have the fastest dissolution profile. The physical properties did not change after 9 months storage in normal conditions.     

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     

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.     

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.     

Free flowing solid dispersions of the anti-HIV drug UC 781 with Poloxamer 407 and a maximum amount of TPGS 1000: Investigating the relationship between physicochemical characteristics and dissolution behaviour

Solid dispersions and physical mixtures made up of the poorly water-soluble drug UC 781, a polymer and a surfactant were prepared to contribute to the understanding of the relationship between physicochemical characteristics and dissolution behaviour. In addition, to facilitate downstream processing while still favouring drug dissolution to a maximum extent, formulation conditions were investigated to obtain a free flowing powder which contains a maximum amount of surfactant. Poloxamer 407, a polyethylene-polypropylene glycol block copolymer, was selected as a suitable polymer based on UC 781 supersaturation results. d-Alpha-tocopheryl polyethyleneglycol succinate 1000 (TPGS 1000) was preferred as a surfactant since it increased UC 781 dissolution when formulated in a self-micro emulsifying drug delivery system (SMEDDS), as compared to TPGS 400, TPGS 4000 and TPGS 6000. Based on flow properties, a TPGS 1000/Poloxamer 407 ratio of 80/20 was used to prepare solid dispersions by spray drying. Pure drugs, physical mixtures and solid dispersions were characterized by differential scanning calorimetry and X-ray powder diffraction. Eutectic phase behaviour was obtained in which the relative distribution of the polyethylene glycol folding was dependent on UC 781 concentration. Drug release was markedly increased when formulated as a solid dispersion with Poloxamer 407 and TPGS 1000. Formulation of solid dispersions did however not further improve the drug dissolution rate compared to that of physical mixtures. Nonetheless, variability of dissolution results was considerably reduced upon solid dispersion formulation.     

Physicochemical characterisation,drug polymer dissolution and in vitro evaluation of phenacetin and phenylbutazone solid dispersions with polyethylene glycol 8000

Poor water solubility leads to low dissolution rate and consequently, it can limit bioavailability. Solid dispersions, where the drug is dispersed into an inert, hydrophilic polymer matrix can enhance drug dissolution. Solid dispersions were prepared using phenacetin and phenylbutazone as model drugs with polyethylene glycol (PEG) 8000 (carrier), by melt fusion method. Phenacetin and phenylbutazone displayed an increase in the dissolution rate when formulated as solid dispersions as compared with their physical mixture and drug alone counterparts. Characterisation of the solid dispersions was performed using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). DSC studies revealed that drugs were present in the amorphous form within the solid dispersions. FTIR spectra for the solid dispersions of drugs suggested that there was a lack of interaction between PEG 8000 and the drug. However, the physical mixture of phenacetin with PEG 8000 indicated the formation of hydrogen bond between phenacetin and the carrier. Permeability of phenacetin and phenylbutazone was higher for solid dispersions as compared with that of drug alone across Caco‐2 cell monolayers. Permeability studies have shown that both phenacetin and phenylbutazone, and their solid dispersions can be categorised as well‐absorbed compounds. © 2011 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:4281–4294, 2011     

The Effect of Carrier-Drug Ratios on Dissolution Performances of Poorly Soluble Drug in Crystalline Solid Dispersion System

The choice of carrier and drug ratio are critical factors as far as the type of solid dispersion is concerned. Amorphous solid dispersion has been cited as the most desirable type among the different types of solid dispersion due to the benefit of amorphicity in increasing the drug solubility of a poorly soluble drug. Recent reports delineated that a partially crystalline solid dispersion system may perform better due to the inherent issue of solution mediated recrystallisation of a completely amorphous system. In oppose to the conventional choice of using amorphous polymer, this study aimed to investigate the use of a crystalline carrier, polyethylene glycol (PEG) for dissolution enhancement of a model poorly soluble drug, Flurbiprofen (FBP), a BCS Class II candidate. Solid dispersions of different FBP to PEG 6000 molar ratios via solvent evaporation were prepared. Physical characterisation of preparations was performed using differential scanning calorimetry (DSC), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and optical microscope. DSC and ATR-FTIR analyses suggest the obtained solid dispersion exhibits crystalline FBP. This is then supported by the optical microscope analysis as the birefringence of crystals was noted. Further increasing the drug-carrier molar ratio to one-to-three and one-to-six showed that there was an amorphous FBP constituent in the system. DSC analysis revealed the melting point depression of FBP by the carrier which signifies interaction between the drug and polymer. Dissolution study showed the solid dispersion of FBP improves the drug solubility and drug release compared to the pure drug. A higher carrier ratio in the formulation results in a higher drug release.     

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.     

Solubility of selected derivatives of 1,4-benzodiazepin-2-one in solid dispersions in PEG 6000

Pharmaceutical availability of diazepam, oxazepam and nitrazepam from solid dispersions of PEG 6000 have been studied in comparison with corresponding physical mixtures and pure benzodiazepines. Selected derivatives of 1,4-benzodiazepin-2-one are poorly water soluble drugs. The aim of this work was to report the properties of diazepam- and nitrazepam-PEG 6000 solid dispersions. Differential scanning calorimetry (DSC) and X-ray diffraction were used to characterize the solid dispersions. The effect of PEG 6000 on the dissolution of selected derivatives of 1,4-benzodiazepin-2-one was investigated. The dissolution of diazepam, oxazepam and nitrazepam from its solid dispersions increased in the presence of PEG 6000.     

Improving the solubility of ampelopsin by solid dispersions and inclusion complexes

The aim of this study was to increase the solubility of ampelopsin (AMP) in water by two systems: solid dispersions with polyethylene glycol 6000 (PEG 6000) or polyvinylpyrrolidone K-30 (PVP K30) and inclusion complexes with beta-cyclodextrin (BCD) and hydroxypropyl-beta-cyclodextrin (HPBCD). The interaction of AMP with the hydrophilic polymers was evaluated by differential scanning calorimetry (DSC), Fourier transformation-infrared spectroscopy (FTIR), scanning electron microscopy (SEM). The results from DSC, FTIR and SEC analyses of solid dispersions and inclusion complexes showed that AMP might exist as an amorphous state or as a solid solution. On the other hand, the SEM images of the physical mixtures revealed that to some extent the drug was present in a crystalline form. The influence of various factors (pH, temperature, type of polymer, ration of the drug to polymer) on the solubility and dissolution rate of the drug were also evaluated. The solubility and dissolution rates of AMP were significantly increased by solid dispersions and cyclodextrin complexes as well as their physical mixtures. The improvement of solubility using polymers was in the following order: HPBCD approximately BCD>PVP K30>PEG 6000.     

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.     

托伐普坦固体分散体的制备及体外溶出特性考察

目的 采用固体分散技术提高难溶性药物托伐普坦的体外溶出度。方法 选用聚维酮K_29/32为载体材料,以溶剂蒸发法制备托伐普坦固体分散体。采用差示扫描量热法(DSC)、X-射线粉末衍射法(XRPD)对所得固体分散体进行鉴定, 并进行溶解度、体外溶出实验。结果 固体分散体的DSC 图谱及X-射线粉末衍射确定了托伐普坦以无定形态分散在载体中, 体外溶解实验表明其溶出较原料药、物理混合物均有明显提高。结论 将托伐普坦与PVP K_29/32制成固体分散体,其分散状态发生了改变,溶出性能明显提高。     

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     

微管蛋白抑制剂SUD-35固体分散体的制备、鉴定及初步体外药效学研究

目的将难溶性微管蛋白抑制剂SUD-35制备成固体分散体,以增加其溶解度及溶出速率。方法以聚乙二醇6000为载体,溶剂-熔融法制备SUD-35固体分散体。采用差示扫描量热分析与X-射线衍射观察药物在载体中的存在状态,并进行溶解度和体外溶出度研究。采用MTT法对SUD-35固体分散体对小鼠白血病L1210细胞药效进行测定。结果 SUD-35固体分散体中SUD-35的溶解度和溶出速率相对原料药和物理混合物均有明显提高,差示扫描量热分析与X-射线衍射结果显示SUD-35以无定型状态存在于固体分散体中,细胞药效结果显示SUD-35固体分散体对小鼠白血病L1210细胞增殖抑制率强于SUD-35纯药。结论聚乙二醇6000为载体制备SUD-35固体分散体,可显著提高SUD-35的溶解度及溶出速率。     

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.     

他克莫司固体分散体的制备及体外溶出度测定

目的:制备他克莫司固体分散体,提高他克莫司的体外溶出度。方法:以体外溶出度为指标,从泊洛沙姆188(Poloxamer188)、聚维酮K30(PVP K30)、羟丙甲纤维素(HPMCE3)、聚乙二醇6000(PEG6000)中筛选最优载体及其比例。并采用差示热量扫描(DSC)、红外光谱(FTIR)、电子扫描电镜(SEM)等进行物相表征。结果:4种不同载体制成的固体分散体均能增加他克莫司体外溶出度,通过比较优选出HPMCE3为最佳载体。物相鉴定表明,他克莫司大部分以无定型状态分散于HPMCE3中。结论:制备他克莫司-HPMCE3固体分散体可以明显提高其体外溶出度,且制备方法简单可行。     

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.     

Similarities in the release rates of different drugs from polyethylene glycol 6000 solid dispersions

The dissolution rates (mg min-1) of 10 drugs, solid dispersed by fusion in polyethylene glycol 6000 (PEG 6000) have been examined by rotating disc methodology. The dispersions generally displayed release rates which were linearly dependent upon the drug concentration (% drug) at high polymer content. However the range over which this linearity was encountered varied unduly, e.g. 0-2% for phenylbutazone and 0-15% for paracetamol. The slope of this line (mean value: 0.451 mg min-1 % -1) was statistically the same for nine of the drugs studied, the exception being griseofulvin which did not form a true solid dispersion but was a microcrystalline dispersion of the drug within the PEG. During fusion, chain scission of the PEG 6000 occurred in the presence of several drugs. PEG 6000 was incompatible with disulfiram, frusemide, chlorothiazide and chlorpropamide.     

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.