A collaborative in vitro dissolution study using the flow-through method

A collaborative in vitro dissolution study has been performed in 4 laboratories using the flow-through method at various hydrodynamic conditions. The USP XXI salicylic acid calibrator tablet was used as test formulation. The results obtained by the flow-through method were compared with data generated using the compendial USP XXI paddle method. The flow-through method was found to produce reproducible and corresponding dissolution data both within and among the different laboratories. It can be concluded that the flow-through method does not produce larger variations, expressed in terms of ranges of amount dissolved at various times, compared to the paddle method. In fact, at some flow conditions, smaller variations were obtained with the flow-through method compared to the paddle method. This was confirmed by the coefficients of variation for the time to dissolve 20, 50, and 80% of the salicylic acid. The coefficient of variation was also found to decrease with increasing hydrodynamic intensity for both dissolution methods. The use of deaerated dissolution medium was found to be a critical experimental factor and the need for a proper pretreatment of the medium must be emphasized.     

Pharmaceutical characterisation and evaluation of cocrystals: Importance of in vitro dissolution conditions and type of coformer

The objectives of this study were to demonstrate the importance of experimental set-up and type of coformer for the enhanced dissolution properties of cocrystals. Carbamazepine–saccharin and carbamazepine–nicotinamide cocrystals were prepared by the sonic slurry method and characterised with SEM, DSC, XRPD and particle size analysis. Solubility and dissolution testing (closed and open system) were performed in compendial media and media with a physiologically relevant amount of surfactant. Carbamazepine cocrystals (1:1 molar ratio) did not show a difference in the equilibrium solubility compared to the carbamazepine in compendial media but a substantial difference was observed in modified media. In compendial media, a faster dissolution rate was obtained only from the carbamazepine–saccharin cocrystal, whereas in modified media both cocrystals had a substantial higher dissolution compared to carbamazepine. With the selected method a clear difference in the dissolution profiles of each cocrystal is shown, driven by the characteristics of the coformer used. This study demonstrated that improved dissolution of carbamazepine from the cocrystal forms can be revealed only by appropriate selection of in vitro conditions. The characteristics of the coformer define a critical variable for dissolution of pharmaceutical cocrystals with important implications for their in vivo performance.     

克拉霉素片体外溶出曲线比较研究

目的 建立克拉霉素片的溶出曲线比较法,比较7家国产制剂与参考制剂在不同溶出介质中的溶出曲线。方法 采用桨法,转速为50r/min,分别用pH6.0、pH6.8、pH7.0缓冲液为溶出介质,参考2015年版《中国药典》克拉霉素含量测定项下的色谱条件和系统适用性,测定累计溶出率,采用单点判定法和相似因子法比较7家国产制剂与参考制剂溶出曲线的相似性。结果 2家国产制剂在pH6.0缓冲液中的溶出曲线与参考制剂相似,1家国产制剂在pH6.8缓冲液中的溶出曲线与参考制剂相似,3家国产制剂在pH7.0缓冲液中的溶出曲线与参考制剂相似。结论 采用pH6.0、pH6.8、pH7.0缓冲液作为溶出介质,可有效区分不同工艺的克拉霉素片;国产制剂与参考制剂的溶出曲线在上述溶出介质中存在一定差异。     

In vitro and in vivo evaluation of carbamazepine-loaded enteric microparticles

The objective of the study was to prepare and evaluate carbamazepine-loaded enteric microparticles produced by a novel coacervation method. An aqueous polymeric stabilizer solution was added to an organic carbamazepine/Eudragit L100-55 solution. Water, which is a non-solvent for the drug and the enteric polymer, caused phase separation and the formation of coacervate droplets. These droplets hardened into microparticles upon further addition of the aqueous phase. The microparticles were characterized with respect to particle size distribution, morphology, encapsulation efficiency, yield, physical state and physical stability of the drug, wettability, in vitro release and in vivo bioavailability. Microparticles with a smooth surface and dense structure were obtained with high encapsulation efficiency (>85%) and yield (>90%). The drug was in a non-crystalline state in the matrix and physically stable for 5 months at room temperature. Under sink conditions, the drug dissolution rate from the microparticles was significantly enhanced compared to the physical mixture and to the pure drug; the release profile of the microparticles was stable after 5 months. Under non-sink conditions, an unstable supersaturated solution of carbamazepine was obtained from microparticles with the subsequent formation of needle-shaped crystals. The high surface area and good wettability of the microparticles, the non-crystalline state of the drug in the matrix and the fast dissolution rate contributed to a significantly enhanced oral bioavailability from the microparticles when compared to the physical mixture.     

In vitro dissolution and oral bioavailability study of fenofibrate nanomatrix system prepared by hot-melt extrusion

Solvent evaporation method for preparation of nanomatrix has the disadvantages, such as residual organic solvent, environmental pollution, explosion-proofing and so on. To overcome these shortcomings, a series of fenofibrate nanomatrix drug delivery system (NDDS) consisting of nano-porous silica Sylysia^®350 (S350) and pH sensitive material Eudragit^® L100-55 (EL100-55) were prepared using hot-melt extrusion (HME), and their in vitro dissolution and in vivo bioavailability were compared. Finally, the formulation with the highest in vivo bioavailability was selected as the optimized formulation for DSC and PXRD characterization. The results showed that the optimized NDDS showed a higher bioavailability than the reference formulation, although there was crystalline form drug remaining in NDDS. The relative bioavailability of the optimized formulation was 157.1% compared with the commercial product Lipanthyl^®. In addition, the relative bioavailability of the optimized formulation was 124.8% in comparison with the formulation prepared by solvent evaporation method, showing that the NDDS prepared by the HME method was effective in improving the bioavailability of fenofibrate. In conclusion, HME was a promising method to prepare NDDS.     

不同厂家消炎片溶出度的考察

目的考察市售不同厂家消炎片的溶出度。方法采用高效液相色谱法检测,计算消炎片的累积溶出率,提取参数(T50、Td、m)进行统计学处理。结果不同厂家的消炎片溶出参数差异有统计学意义(P<0.01)结论消炎片有必要增加溶出度检查,以控制质量。     

尼群地平固体分散片的制备及其体外溶出度的测定

目的 制备尼群地平(NT)固体分散体片，提高其溶出度：方法 以聚乙烯吡咯烷酮(PVPk30)为载体，用溶剂法制备NT固体分散体；显微镜观察和差示热分析(DTA)鉴别药物在载体中的状态；制备普通片和固体分散体片，测定溶出度，并与市售国产片相比。结果 DTA曲线表明药物在固体分散体中以非晶体状态存在，其体外溶出速率明显提高，20min的累计释放率为73．2％，而普通片及市售国产片分别为22．5％和21．7％。结论 NT制成固体分散体片能明显增加NT的体外溶出度。     

伊曲康唑固体分散体制备及体外溶出实验

目的:运用固体分散体技术提高难溶性药物伊曲康唑的溶解度及体外溶出速率.方法:选用聚乙烯吡咯烷酮(PVPK30)为载体,采用喷雾干燥法制备伊曲康唑固体分散体,通过差热分析及X射线衍射对固体分散体进行鉴定,比较考察伊曲康唑及其物理混合物和固体分散体的溶出特性.结果:差热分析、X射线衍射图谱表明药物以无定形状态分散于载体中;体外溶出结果表明固体分散体能显著增加药物在水及人工胃液中的溶出度(45 min时1:4固体分散体体外溶出度为伊曲康唑的11.5倍.1:4固体分散体在0.1 mo1·L-1盐酸中溶解度是伊曲康唑的67倍).结论:伊曲康唑固体分散体能明显提高伊曲康唑的溶解度及体外溶出速率.     

Investigation on in vitro dissolution rate enhancement of indomethacin by using a novel carrier sucrose fatty acid ester

Background and the purpose of the study

The purpose of the present investigation was to characterize and evaluate solid dispersions (SD) of indomethacin by using a novel carrier sucrose fatty acid ester (SFE 1815) to increase its in vitro drug release and further formulating as a tablet.

Methods

Indomethacin loaded SD were prepared by solvent evaporation and melt granulation technique using SFE 1815 as carrier in 1:0.25, 1:0.5 1:0.75 and 1:1 ratios of drug and carrier. Prepared SD and tablets were subjected to in vitro dissolution studies in 900 mL of pH 7.2 phosphate buffer using apparatus I at 100 rpm. The promising SD were further formulated as tablets using suitable diluent (DCL 21, Avicel PH 102 and pregelatinised starch) to attain the drug release similar to that of SD.. The obtained dissolution data was subjected to kinetic study by fitting the data into various model independent models like zero order, first order, Higuchi, Hixon-Crowell and Peppas equations. Drug and excipient compatibility studies were confirmed by fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and scanning electron microscopy.

Results

The in vitro dissolution data exhibited superior release from formulation S₆ with 1:0.5 drug and carrier ratio using solvent evaporation technique than other SDs prepared at different ratio using solvent evaporation and melt granulation technique. The in vitro drug release was also superior to that of the physical mixtures prepared at same ratio and also superior to SD prepared using common carriers like polyvinyl pyrollidone and PEG 4000 by solvent evaporation technique. Tablets (T₈) prepared with DCL21 as diluent exhibited superior release than the other tablets. The tablet formulation (T₈) followed first order release with Non-Fickian release.

Conclusion

SFE 1815 a novel third generation carrier can be used for the preparation of SD for the enhancement of in vitro drug release of indomethacin an insoluble drug belonging to BCS class II.     

茴拉西坦分散片制备及体外溶出度影响因素考察

目的制备茴拉西坦分散片(ADT),考察其体外溶出特性和影响溶出度的因素。方法采用正交试验设计方案,以溶出度为考察指标,对茴拉西坦分散片进行处方筛选,考察可能影响溶出度和分散均匀性的因素。结果按优化处方制备的分散片溶出较好,分散较快。结论优选处方制备的茴拉西坦分散片溶出度好,影响其溶出度的主要因素为PVPP、L-HPC用量和PVP K30浓度。     

Dissolution of poorly water-soluble drugs in biphasic media using USP 4 and fiber optic system

A novel in-vitro dissolution system based on the principle of flow-through technique has been designed to evaluate the in-vitro release rate of poorly water-soluble compounds. The flow through apparatus (USP 4) has been coupled with the compendial dissolution apparatus (USP apparatus 2). A bi-phasic dissolution medium is used to achieve sink conditions. The dissolved drug is continuously removed from the aqueous phase into the organic phase of the dissolution medium, mimicking the process of absorption in the systemic circulation. The in vitro release profiles obtained from this dissolution model was able to distinguish the formulation changes of several poorly water-soluble drugs from their dosage forms. For AMG 517, the model drug, excellent rank order correlation has been obtained between the in-vitro release and the in-vivo absorption of the drug from several different dosage forms and their formulations. In addition, for several commercial formulations, the model successfully discriminated between the bioequivalent and non-bioequivalent formulations.     

维甲酸自乳化制剂的含量测定及体外溶出评价

目的:研究维甲酸RA自乳化制剂的含量测定方法及体外溶出行为.方法:采用HPLC法测定维甲酸RA自乳化制剂的药物含量,与市售胶囊比较,考察RA自乳化制剂体外溶出行为.结果:与市售胶囊剂相比,以水为溶出介质,维甲酸RA自乳化制剂15min可以溶出80%以上,而市售胶囊只溶出不到5%.自乳化制剂可以显著提高药物的体外溶出.     

醋酸钙片剂与胶囊剂体外溶出度及其磷结合效果的比较

目的 比较醋酸钙片剂与胶囊剂中钙离子的体外溶出度及钙磷结合的特性.方法 建立钙离子与磷酸盐体外结合的定量指示方法,考察不同浓度和不同pH环境下的钙磷结合特性,进而比较醋酸钙片剂与胶囊剂的体外溶出度和钙磷结合效果.结果 钙离子与磷酸盐的结合与两者浓度呈正相关,钙磷结合量随钙离子和磷酸盐浓度的增大而增大,在pH7时结合量最大;醋酸钙片剂与胶囊剂体外溶出速率不同,但溶出完全后两者体外钙磷结合效果相同.结论 所用方法简单易操作,结果准确.在体外,醋酸钙片剂和胶囊剂均能有效与磷酸盐结合.     

HPLC determination of olanzapine and carbamazepine in their nicotinamide cocrystals and investigation of the dissolution profiles of cocrystal tablet formulations

Abstract

Cocrystals have recently gained importance in the pharmaceutical industry. In this study, olanzapine and carbamazepine cocrystals were synthesized by using nicotinamide as cocrystal forming agent to achieve improvements in the physicochemical characteristics of the active ingredients. An HPLC method was developed to determine the amount, thus, the stoichiometric ratios of olanzapine and carbamazepine in the synthesized cocrystals. Olanzapine:nicotinamide and olanzapine tablet formulations were prepared and the developed HPLC method was applied successfully in order to compare the dissolution profiles of these formulations. An ACE 5 CN, 25?cm?×?4.6?mm, 5?µm column was used and a gradient elution program was performed for simultaneous determination of olanzapine, carbamazepine and nicotinamide. Phosphate buffer (pH 5.0, 25?mM) and methanol was used in a ratio from 80:20 to 70:30 while the flow rate was 1?mL?min^?1 for the elution of the compounds within 12?min. In conclusion, two different aims were achieved, the first one was to indicate the stoichiometric ratios of the active ingredients olanzapine and carbamazepine with nicotinamide in their cocrystals, and the second one was the comparison of the dissolution profiles of the olanzapine and olanzapine:nicotinamide cocrystal formulations. It was found that the cocrystal formulation with nicotinamide improved the dissolution profile of olanzapine.     

Development and application of a validated HPLC method for the analysis of dissolution samples of levothyroxine sodium drug products

A rapid, selective, and sensitive gradient HPLC method was developed for the analysis of dissolution samples of levothyroxine sodium tablets. Current USP methodology for levothyroxine (L-T(4)) was not adequate to resolve co-elutants from a variety of levothyroxine drug product formulations. The USP method for analyzing dissolution samples of the drug product has shown significant intra- and inter-day variability. The sources of method variability include chromatographic interferences introduced by the dissolution media and the formulation excipients. In the present work, chromatographic separation of levothyroxine was achieved on an Agilent 1100 Series HPLC with a Waters Nova-pak column (250 mm × 3.9 mm) using a 0.01 M phosphate buffer (pH 3.0)-methanol (55:45, v/v) in a gradient elution mobile phase at a flow rate of 1.0 mL/min and detection UV wavelength of 225 nm. The injection volume was 800 μL and the column temperature was maintained at 28°C. The method was validated according to USP Category I requirements. The validation characteristics included accuracy, precision, specificity, linearity, and analytical range. The standard curve was found to have a linear relationship (r(2)>0.99) over the analytical range of 0.08-0.8 μg/mL. Accuracy ranged from 90 to 110% for low quality control (QC) standards and 95 to 105% for medium and high QC standards. Precision was <2% at all QC levels. The method was found to be accurate, precise, selective, and linear for L-T(4) over the analytical range. The HPLC method was successfully applied to the analysis of dissolution samples of marketed levothyroxine sodium tablets.     

对比分析卡马西平联合丙戊酸钠、单用卡马西平治疗癫痫的临床疗效及其不良反应

目的:分析卡马西平联合丙戊酸钠、单用卡马西平治疗癫痫的疗效及不良反应。方法:选择我院2018年1—12月收治的癫痫患者62例作为研究对象,按照治疗方法的不同分为研究组(卡马西平联合丙戊酸钠治疗)和对照组(卡马西平治疗),比较两组治疗前后的癫痫发作次数和每次发作时间、MoCA评分、HAMD评分、HAMA评分。结果:研究组临床指标在治疗后均显著优于对照组(P<0.05);两组不良反应发生率比较差异无统计学意义(P>0.05)。结论:卡马西平联合丙戊酸钠能有效改善癫痫发作次数和发作时间,提高认知水平,有利于情绪功能改善,疗效突出,安全性高,值得推广。     

Improved solubility and in vitro dissolution of Ibuprofen from poloxamer gel using eutectic mixture with menthol

To improve the solubility and in vitro dissolution of poorly water-soluble ibuprofen with poloxamer and menthol, the effects of menthol and poloxamer 188 on the aqueous solubility of ibuprofen were investigated. The dissolution study of ibuprofen delivered by poloxamer gels composed of poloxamer 188 and menthol were performed. In the absence of poloxamer, the solubility of ibuprofen increased until the ratio of menthol to ibuprofen increased from 0:10 to 4:6, followed by an abrupt decrease in solubility above the ratio of 4:6, indicating that 4 parts of ibuprofen formed eutectic mixture with 6 parts of menthol. In the presence of poloxamer 188, the solutions with the same ratio of menthol to ibuprofen showed abrupt increase in the solubility of ibuprofen. Furthermore, the solution with ratio of 4:6 showed more than 2.5- and 6-fold increase in the solubility of ibuprofen compared with that without poloxamer and that without menthol, respectively. The poloxamer gel with menthol/ibuprofen ratio of 1:9 and higher than 15% poloxamer 188 showed the maximum solubility of ibuprofen, 1.2 mg/ml. Menthol improved the dissolution rates of ibuprofen from poloxamer gels. Dissolution mechanism showed that the dissolution rate of ibuprofen from the poloxamer gels without menthol was independent of the time, but the drug might be dissolved from the poloxamer gels with menthol by Fickian diffusion. Thus, the poloxamer gels developed using eutectic mixture with menthol, which gave the improved solubility and dissolution of drug, are potential candidates for ibuprofen-loaded transdermal and rectal delivery system.     

The influence of amitriptyline and carbamazepine on levomepromazine metabolism in human liver: An in vitro study

BackgroundJoint administration of phenothiazine neuroleptics and an antidepressant or carbamazepine is applied in the therapy of many complex psychiatric disorders. The aim of the present study was to investigate possible effects of the tricyclic antidepressant drug amitriptyline and the anticonvulsant drug carbamazepine on the metabolism of the aliphatic-type phenothiazine neuroleptic levomepromazine in human liver.MethodsThe experiment was performed in vitro using human liver microsomes. The rates of levomepromazine 5-sulfoxidation and N-demethylation (levomepromazine concentrations: 5, 10, 25 and 50 μM) were assessed in the absence and presence of amitriptyline or carbamazepine added in vitro (drug concentrations: 1, 2.5, 5, 10, 25 μM).ResultsA kinetic analysis of levomepromazine metabolism carried out in the absence or presence of carbamazepine showed that the anticonvulsant drug potently inhibited levomepromazine 5-sulfoxidation (K_i = 7.6 μM, non-competitive inhibition), and moderately decreased the rate of levomepromazine N-demethylation (K_i = 15.4 μM, mixed inhibition) at therapeutic drug concentrations. On the other hand, amitriptyline weakly diminished the rate of levomepromazine 5-sulfoxidation (K_i = 63 μM, mixed inhibition) and N-demethylation (K_i = 47.7 μM, mixed inhibition).ConclusionRegarding the central and peripheral effects of levomepromazine and some of its metabolites, the observed metabolic interaction between this neuroleptic and carbamazepine may be of pharmacological and clinical importance.     

Comparison of the in vitro dissolution properties and in vivo steady-state pharmacokinetics of two sustained-release theophylline preparations

The sustained-release properties and relative bioavailability of Theolin^® Retard and Pharphylline^® Retard were studied in eight healthy adults after treatment for five days with twice daily 450 mg, respectively 425 mg. During the day-time dosing interval on the fourth and fifth day theophylline plasma concentrations were assayed by HPLC. After intake of Theolin^® Retard, minimum theophylline plasma concentrations were significantly higher, fluctuations in theophylline plasma concentrations were significantly smaller andt ₇₅ (the period within a dosing interval during which the plasma concentration exceeds 75% of the maximal concentration) was significantly longer than after Pharphylline^® Retard. Maximal concentrations and AUC values were not significantly different. For both products the plasma concentration time-curves on day 5 were significantly lower than on day 4.In vitro dissolution tests confirmed the more sustained release of theophylline from Theolin^® Retard. These results indicate an equal extent of absorption from the two products but better sustained-release properties for Theolin^® Retard.     

In vitro study of sirolimus release from a drug-eluting stent: Comparison of the release profiles obtained using different test setups

In this study drug release from the CYPHER™ stent, the gold standard in drug-eluting stent therapy until the end of its marketing in 2011/2012, was systematically evaluated using different in vitro release tests. The test systems included incubations setups, the reciprocating holder apparatus (USP 7), the flow-through cell apparatus (USP 4) and the vessel-simulating flow-through cell (vFTC) specifically designed for stent testing. The results obtained show a large variability regarding the fractions released into the media after 7 d ranging from 38.6% ± 4.5% to 74.6% ± 1.2%. The lowest fraction released was observed in the vFTC and the highest in an incubation setup with frequently changed media of a volume of 2 mL. Differences were even observed when using fairly similar and simple incubations setups with mere changes of the media volume, under maintenance of sink conditions, and of the vessel geometry. From these data it can be concluded, that in vitro release even from a slow releasing drug-eluting stent is greatly influenced by the experimental conditions and care must be taken when choosing a suitable setup. Comparison of the obtained in vitro release profiles to published in vivo data did not result in a distinct superiority of any of the tested methods regarding the predictability for the situation in vivo due to large differences in the reported in vivo data. However, this comparison yielded that the release observed in vitro using the 2 mL incubation setup and the reciprocating holder apparatus may be faster than the reported in vivo release. The results of this study also emphasize the necessity to use highly standardized release tests when comparisons between results from different experiments or even different labs are to be performed. In this context, the compendial methods are most likely offering the highest degree of standardization.