Solubility Prediction of Satranidazole in Propylene Glycol-Water Mixtures Using Extended Hildebrand Solubility Approach

Extended Hildebrand solubility approach is used to estimate the solubility of satranidazole in binary solvent systems. The solubility of satranidazole in various propylene glycol-water mixtures was analyzed in terms of solute-solvent interactions using a modified version of Hildebrand-Scatchard treatment for regular solutions. The solubility equation employs term interaction energy (W) to replace the geometric mean (δ₁δ₂), where δ₁ and δ₂ are the cohesive energy densities for the solvent and solute, respectively. The new equation provides an accurate prediction of solubility once the interaction energy, W, is obtained. In this case, the energy term is regressed against a polynomial in δ₁ of the binary mixture. A quartic expression of W in terms of solvent solubility parameter was found for predicting the solubility of satranidazole in propylene glycol-water mixtures. The expression yields an error in mole fraction solubility of ~3.74%, a value approximating that of the experimentally determined solubility. The method has potential usefulness in preformulation and formulation studies during which solubility prediction is important for drug design.     

Prediction of Intestinal Drug Absorption Properties by Three-Dimensional Solubility Parameters

Purpose. The purpose of this study was to investigate the use of solubility parameters for the prediction of gastrointestinal absorption sites and absorption durations of drugs. Methods. Three-dimensional solubility parameters of drug substances were calculated using an advanced parameter set based on the group contribution methods of Fedors and Van Krevelen/Hoftyzer. The results of the calculations were illustrated via Bagley diagram and related to absorption data reported in the literature. Results. Solubility parameters of drugs which are known to be absorbed over a long period in human's digestive tract were found in a limited area within the Bagley diagram. From the three-dimensional solubility parameters of these substances, a region for optimal absorption with the centre coordinates _v = 20.3 (J cm^–3)^0.5 and _h = 11.3 (J cm^–3)^0.5 could be derived. Drugs with absorption sites along the whole gastrointestinal tract were found in this area. Drugs which are preferably absorbed from upper parts of the intestine are located in another typical region with partial solubility parameters _h of more than 17 (J cm^–3)^0.5. Conclusions. The method which is presented in this paper appears as a simple but effective method to estimate the absorption behaviour of new substances in drug research and development.     

The Expanded Hansen Approach to Solubility Parameters. Paracetamol and Citric Acid in Individual Solvents

In this study two solubility-parameter models have been compared using as dependent variables the logarithm of the mole fraction solubility, lnX₂^e, and ln(α)/U (originally used in the extended Hansen method), where α is the activity coefficient and U is a function of the molar volume of the solute and the volume fraction of the solvent. The results show for the first time the proton-donor and -acceptor hydrogen-bonding capacities of paracetamol, as measured by the acidic and basic partial-solubility parameters. The influence of solvents on the differential scanning calorimetry (DSC) pattern of the solid phases was also studied in relation to the solubility models tested. Citric acid was chosen as a test substance because of its high acidity and its proton donor capacity to form hydrogen bonds with basic solvents. The partial acidic and basic solubility parameters obtained from multiple regression were consistent with this property, validating the model chosen. The results show that the more direct lnX₂^e variable was more suitable for fitting both models, and the four-parameter model seemed better for describing the interactions between solvent and solute.     

Solubility Prediction of Satranidazole in Aqueous N,N-dimethylformamide Mixtures Using Extended Hildebrand Solubility Approach

The solubility of satranidazole in several water–N,N-dimethylformamide mixtures was analysed in terms of solute–solvent interactions and data were treated on the basis of extended Hildebrand solubility approach. The solubility profile of satranidazole in water–N,N-dimethylformamide mixtures shows a curve with a solubility maxima well above the ideal solubility of drug. This is attributed to solvation of the drug with the water–N,N-dimethylformamide mixture, and indicates that the solute–solvent interaction energy (W) is larger than the geometric mean (δ₁δ₂) of regular solution theory. The new approach provides an accurate prediction of solubility once the interaction energy (W) is obtained. In this case, the energy term is regressed against a polynomial in δ₁ of the binary solvent mixture. A quartic expression of W in terms of solvent solubility parameter was found for predicting the mole fraction solubility of satranidazole in the studied mixtures. The method has potential usefulness in preformulation and formulation studies during which solubility prediction is important for drug design.     

Benzoyl Peroxide Solubility and Stability in Hydric Solvents

Saturated solubility and reaction rate constants for the decomposition of benzoyl peroxide in solution and suspension were determined for use in formulation development. The solvents studied included ethanol, propylene glycol, and cosolvent mixtures of PEG 400 and water. The solubility of benzoyl peroxide was inversely related to the solvent polarity, with greater solubility occurring with semipolar solvents. The stability of benzoyl peroxide in solution was dependent on the solvent, concentration of benzoyl peroxide, and temperature. The compound was least stable in PEG 400. Stability was improved when water was added to PEG 400. Similar solvent effects were observed in suspension. In benzoyl peroxide suspensions of PEG 400 and PEG 400/water blends, benzoyl peroxide stability was dependent on solubility, with improved stability occurring in blends where the benzoyl peroxide was least soluble. Thus, solution formulations of benzoyl peroxide in pharmaceutically acceptable solvents are unlikely to show good stability; however, suspension formulations should be reasonably stable if the vehicle is selected to provide low benzoyl peroxide solubility.     

Prediction of Shrinkage of Individual Parameters Using the Bayesian Information Matrix in Non-Linear Mixed Effect Models with Evaluation in Pharmacokinetics

Purpose

When information is sparse, individual parameters derived from a non-linear mixed effects model analysis can shrink to the mean. The objective of this work was to predict individual parameter shrinkage from the Bayesian information matrix (M _BF ). We 1) Propose and evaluate an approximation of M _BF by First-Order linearization (FO), 2) Explore by simulations the relationship between shrinkage and precision of estimates and 3) Evaluate prediction of shrinkage and individual parameter precision.

Methods

We approximated M _BF using FO. From the shrinkage formula in linear mixed effects models, we derived the predicted shrinkage from M _BF . Shrinkage values were generated for parameters of two pharmacokinetic models by varying the structure and the magnitude of the random effect and residual error models as well as the design. We then evaluated the approximation of M _BF FO and compared it to Monte-Carlo (MC) simulations. We finally compared expected and observed shrinkage as well as the predicted and estimated Standard Errors (SE) of individual parameters.

Results

M _BF FO was similar to M _BF MC. Predicted and observed shrinkages were close . Predicted and estimated SE were similar.

Conclusions

M _BF FO enables prediction of shrinkage and SE of individual parameters. It can be used for design optimization.     

三个参数对临床用药的指导意义

临床上对患者作出明确诊断,确定使用药物很重要。药物动力学的半衰期(t12)、血浆蛋白结合率(pb%)和解离指数(pka)等三个参数对医师用药具有指导意义,现分述如下。1　半衰期(t12)[1]半衰期又称半寿期、残半期,是药物动力学的一个重要参数。常分为吸收半衰期、分布半衰期和消除半衰期。一般无特殊说明,药物的半衰期均指消除半衰期。t12是指血浆中药物的浓度下降一半所需的时间。多数药物都是按一级动力学方程消除,从用药后任何时间算起,在原有药物浓度的基础上,下降一半所需的时间。对于一具体药物来说都是固定的常数,它与血药浓度高低没有关…     

溶解度参数在固体分散体中的应用

介绍溶解度参数在固体分散体中的应用, 利用基团贡献法求出药物的溶解度参数.选择与药物溶解度参数差在1.6~7.5的载体为固体分散体载体的选择提供简单实用的方法.     

Viscoelastic Properties of Polyacrylic Acid Gels in Mixed Solvents

The objective of this study is to investigate the viscoelastic properties of Carbopol 934P polymeric systems in a variety of mixtures of pharmaceutical solvents. Carbopol 934P neutralized with a 1:1 equivalent ratio of triethanolamine was dissolved in various binary or ternary solvent mixtures consisting of propylene glycol, glycerol formal, and water. Dynamic moduli G and G, complex viscosities, and , and loss tangent, tan, were examined over a frequency range of 10-3 to 10 Hz using an oscillatory viscoelastic rheometer at 30°C. The results indicated that for 0.5-1.5 wt% neutralized Carbopol in ternary mixtures, G and G increased by 3-4 orders of magnitude and the phase angle decreased from 80 to 25° when the water content in the solvent mixture increased from 10 to 80 wt%. These studies also indicated that the addition of water to nonaqueous Carbopol 934P polymer systems transforms them from low-viscosity solutions to gels with significant elastic behavior involving physical interaction and entanglement of polymer segments with solvents.     

A Method to Predict the Equilibrium Solubility of Drugs in Solid Polymers near Room Temperature Using Thermal Analysis

A method is presented for determining the equilibrium solubility of a drug in a solid polymer at or near room temperature, which represents a typical storage temperature. The method is based on a thermodynamic model to calculate the Gibbs energy change ΔG_SS associated with forming a binary drug–polymer solid solution from the unmixed polymer and solid drug. The model includes contributions from heat capacity differences between the solid solution and the corresponding unmixed components, breaking up of the solid drug structure, and drug–polymer mixing. Calculation of ΔG_SS from thermal analysis data is demonstrated, and it is shown that minima of plots of ΔG_SS versus the dissolved drug concentration represent the equilibrium drug solubility in the polymer. Solid solutions were produced for drug–polymer systems (griseofulvin, indomethacin, itraconazole; PVP K30, Eudragit L100, Eudragit E100) in drug weight fractions up to ～25%. At 25°C, it was seen that heat capacity effects were important in determining the drug solubility. It was concluded that drug solubilities in solid polymers can be determined using thermal analysis, and must include heat capacity effects when evaluated near room temperature.     

Predicting the Solubility of Drugs in Solvent Mixtures: Multiple Solubility Maxima and the Chameleonic Effect

Abstract— An approach to reproduce the solubility profile of a drug in several solvent mixtures showing two solubility maxima is proposed in this work. The solubility of sulphamethoxypyridazine was determined at 25°C in several mixtures of varying polarity (hexane: ethyl acetate, ethyl acetate:ethanol and ethanol: water). Sulphamethoxypyridazine was chosen as a model drug because of its proton-donor and proton-acceptor properties. A plot of the mole fraction of the drug vs the solubility parameter of the solvent mixtures shows two solubility peaks. The two peaks found for sulphamethoxypyridazine demonstrate the chameleonic effect as described by Hoy and suggest that the solute-solvent interaction does not vary uniformly from one mixture to another. The different behaviour of the drug in mixtures of two proton-donor and proton-acceptor solvents (alcohol and water), and in mixtures of one proton acceptor (ethyl acetate) and one proton donor-proton acceptor (ethanol) is rationalized in terms of differences in the proton donor-acceptor ability of the solvent mixtures. An approach based on the acidic and basic partial solubility parameters together with the Hildebrand solubility parameter of the solvent mixtures is developed to reproduce the experimental results quantitatively. The equation predicts the two solubility maxima as found experimentally, and the calculated values closely correspond to the experimental values through the range composition of the solvent mixtures. These results show that the chameleonic effect can be described in a quantitative way in terms of Lewis acid-base interactions; this approach can assist the product formulator to choose the proper solvent mixture for a new drug. A good solvent blend should result in a solubility parameter close to that of the drug; the acidic and basic partial solubility parameter values should provide maximum acid-base interaction of the mixed solvent with the drug. The failure in one of these conditions results in decreased solubility. Solubility parameters as well as the acidic and basic parameters are tabulated or they can be obtained from group contribution methods, making easier the evaluation of the best solvent mixture for a drug.     

增加难溶性药物溶解度方法新进展

如何增加难溶性药物溶解度是药剂学设计的重点。现就近年来微粉化技术、环糊精包含技术、固体分散技术等传统技术和其它一些新方法对增加难溶性药物溶解度的新进展作一综述。     

Prediction of an Outcome Using Trajectories Estimated from a Linear Mixed Model

In longitudinal data, interest is usually focused on the repeatedly measured variable itself. In some situations, however, the pattern of variation of the variable over time may contain information about a separate outcome variable. In such situations, longitudinal data provide an opportunity to develop predictive models for future observations of the separate outcome variable given the current data for an individual. In particular, longitudinally changing patterns of repeated measurements of a variable measured up to time t , or trajectories, can be used to predict an outcome measure or event that occurs after time t .

In this article, we propose a method for predicting an outcome variable based on a generalized linear model, specifically, a logistic regression model, the covariates of which are variables that characterize the trajectory of an individual. Since the trajectory of an individual contains estimation error, the proposed logistic regression model constitutes a measurement error model. The model is fitted in two steps. First, a linear mixed model is fitted to the longitudinal data to estimate the random effect that characterizes the trajectory for each individual while adjusting for other covariates. In the second step, a conditional likelihood approach is applied to account for the estimation error in the trajectory. Prediction of an outcome variable is based on the logistic regression model in the second step. The receiver operating characteristic curve is used to compare the discrimination ability of a model with trajectories to one without trajectories as covariates. A simulation study is used to assess the performance of the proposed method, and the method is applied to clinical trial data.     

The Estimation of Solubility in Binary Solvents: Application of the Reduced 3-Suffix Solubility Equation to Ethanol–Water Mixtures

The reduced 3-suffix solubility equation (R3SSE) is applied to the characterization of solubility in the ethanol–water system. The data needed are the solubility of the compound in each of the pure solvents and at one ethanol–water composition. This composition has been estimated from solubility data to be 0.56 volume fraction of ethanol. The solubility obtained at this volume fraction is used to estimate the ternary solute–solvent interaction constant, C ₂. The R3SSE, with the C ₂ thus obtained, predicts the mixed solvent solubilities of the compounds tested, as accurately as that obtained from several volume fractions. The superiority of the R3SSE over two related equations—a simple second-degree polynomial equation and a simplified form of the R3SSE which neglects contributions to solubility from the solvent mixture—is also demonstrated for a number of solutes.     

GC法检测氟康唑原料药中的有机溶剂残留量

目的:建立检测氟康唑原料药中有机溶剂残留量的方法。方法:采用气相色谱法。色谱柱为DB-17毛细管柱,柱温采用程序升温,载气为N2,氢火焰离子化检测器,测定原料药中残留溶剂丙酮、乙酸乙酯、甲苯。结果:丙酮、乙酸乙酯、甲苯的检测浓度线性范围分别为128～2555(r=0.9997)、130～2589(r=0.9995)、27～530μg·mL-(1r=0.9991);平均回收率分别为98.1%、98.0%、97.5%,RSD分别为2.3%、1.3%、1.5%,最低检测限分别为11、7.1、0.6ng;3批样品中均未检出3种有机溶剂。结论:所建立的方法简便、灵敏、准确,能够有效分离和准确检测氟康唑原料药中的有机溶剂残留量。     

利用Excel规划求解法计算药物静脉注射药动学方程参数最优解

目的:利用Excel规划求解功能建立一种简便的计算药物静脉注射药动学方程参数最优解的方法。方法:采用Excel规划求解功能获得药物静脉注射后一、二室模型药动学参数和隔室模型参数,并与DAS和残数法得到的结果进行比较。结果:Excel规划求解可在一定约束条件下获得一、二室模型参数的最优解,与DAS运行结果完全一致。结论:Excel规划求解法可用于临床药物静脉注射后一、二室模型参数的计算。     

化妆品和药品残留溶剂测定方法差异的探讨

摘 要 目的：对《化妆品安全技术规范》2015年版和中国药典2015年版中残留溶剂检测方法的异同进行了归纳与总结,为《化妆品安全技术规范》中残留溶剂检测方法的提高完善提供参考。方法: 分别比较分析了《化妆品安全技术规范》2015年版和中国药典2015年版中检测残留溶剂的种类和限度、残留溶剂检测方法的特点。结果: 中国药典残留溶剂的测定方法更为详细具体,《化妆品安全技术规范》残留溶剂的测定方法是一种通用的检测方法,所使用的方式方法及流程可扩展至更多溶剂的测定,部分有检测方法的溶剂缺乏限度。结论: 建议《化妆品安全技术规范》增加通用方法能检测的残留溶剂的种类,参照中国药典对化妆品中限用的残留溶剂制定类似药典的限度表,对化妆品残留溶剂的控制将更加完善,确保产品的质量安全。     

Modeling the Solubility of Pharmaceuticals in Pure Solvents and Solvent Mixtures for Drug Process Design

The knowledge of the solubility of pharmaceuticals in pure solvents and solvent mixtures is crucial for designing the crystallization process of drug substances. The first step in finding optimal crystallization conditions is usually a solvent screening. Since experiments are very time consuming, a model which allows for solubility predictions in pure solvents and solvent mixtures based only on a small amount of experimental data is required. In this work, we investigated the applicability of the thermodynamic model perturbed-chain statistical associating fluid theory (PC-SAFT) to correlate and to predict the solubility of exemplary five typical drug substances and intermediates (paracetamol, ibuprofen, sulfadiazine, p-hydroxyphenylacetic acid, and p-aminophenylacetic acid) in pure solvents and solvent mixtures. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:4205–4215, 2009