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.     

Solid-state compatibility screening of excipients suitable for development of indapamide sustained release solid-dosage formulation

Differential scanning calorimetry and Fourier transform infrared spectroscopy were applied as screening analytical methods to assess the solid-state compatibility of indapamide (4-chloro-N-(2-methyl-2,3-dihydroindol-1-yl)-3-sulfamoyl-benzamide) with several polymers aimed for development of 24?h sustained release solid-dosage formulation. After the initial research phase which was directed towards selection of suitable polymer matrices, based on their solid-state compatibility with the studied pharmaceutical active ingredient, the second phase of evaluation was intended for compatibility selection of other excipients required to complete a sustained release formulation. The preformulation studies have shown that polyvinylpyrrolydone/polyvinyl acetate might be considered incompatible with indapamide, and the implementation of this polymer career should be avoided in the case of the entitled development. The experimental data additionally have revealed that sorbitol is incompatible with indapamide. The obtained results afforded deeper insight in to the solid-state stability of the studied binary systems and pointed out directions for further development of indapamide sustained release solid-dosage formulation.     

Some Preformulation Studies of Pyruvic Acid and Other α-Keto Carboxylic Acids in Aqueous Solution: Pharmaceutical Formulation Implications for These Peroxide Scavengers

The purpose of this study is to assess some of the variables determining the aldol-like condensation of pyruvic acid (1), a peroxide scavenger, in aqueous solution to parapyruvic acid and higher oligomers. Its stability is compared to 3 other α-keto carboxylic acids, 2 with sterically hindered methylene groups alpha to the keto functionality (2-3) and phenylglyoxylic acid (4) with no methylene group. High-performance liquid chromatography, nuclear magnetic resonance, and liquid chromatography mass spectroscopy techniques are used in the kinetics and product analyses. 1 condensation is concentration dependent and base catalyzed above pH 7, consistent with the reaction mechanism proceeding through the attack of the fraction of the methylene group, alpha to the keto group, in its anionic form, at the keto group of a second molecule of 1. The major product is confirmed to be parapyruvic acid, but higher-order oligomers are also observed. All 3 of the other α-keto carboxylic acids 2-4 are considerably less reactive, with 4 being completely stable. Stable solutions of 1 can be prepared by the use of relatively dilute solutions maintained at slightly acidic pH values. 1 prevents the oxidation of methionine on addition of hydrogen peroxide.     

处方前研究的意义及方法

简略介绍处方前研究的意义、一般程序和方法。     

Preparation and Characterization of Salt Forms of Enalapril

Selection of an optimal salt form of a drug candidate is a vital component of preformulation stage of drug development. In this study, six salts of enalapril – citrate, mesylate, tartrate, malate, besylate and tosylate – were prepared and characterized by Mass Spectroscopy, Differential Scanning Calorimetry, Thermogravimetric Analysis, Microscopy, Powder X-ray Diffraction, Karl Fischer Titration, High Performance Liquid Chromatography, Fourier-Transform Infra-red Spectroscopy and Head Space Gas Chromatography. All the six salts were subjected to a tiered screening involving five stages in the following order: crystallinity, hygroscopicity, solubility, stability and flow/compactability. Enalapril malate showed encouraging profile because of its lower hygroscopicity, higher solubility, good solid state stability, and better flow and compactability, in comparison to the marketed maleate salt.     

Cocrystal and Salt Forms of an Imidazopyridazine Antimalarial Drug Lead

Cocrystallization and salt formation were used to produce new multicomponent forms of a novel antimalarial imidazopyridazine drug lead (MMV652103) that displayed improved physicochemical properties. The drug lead had earlier shown good in vitro potency against multidrug resistant (K1) and sensitive (NF54) strains of the human malaria parasite Plasmodium falciparum, and high in vivo efficacy in both Plasmodium berghei and Plasmodium falciparum mouse models. A major drawback of MMV652103 is its limited aqueous solubility. Various new supramolecular products, including several multicomponent solid forms, are reported here, namely 3 cocrystal forms with the dicarboxylic acid coformers adipic acid, glutaric acid, and fumaric acid, and a salt form with malonic acid. These were characterized by thermal methods and their structures elucidated by single-crystal X-ray diffraction. A customized solubility experiment was performed in fasted-state simulated intestinal fluid for comparison of the solubility behavior of each new form of the drug lead with that of the untreated starting material. All of the multicomponent forms showed an improvement in the maximum concentrations (C_max) attained by the drug lead and the rate at which it dissolved. The recorded C_max values exceeded the concentration of the untreated compound by factors in the range 4.6-5.6.     

格列吡嗪pH非依赖型缓释片的处方前研究

目的 开发一种基于微环境pH调控技术的格列吡嗪pH非依赖型缓释片,对格列吡嗪、辅料、pH调节剂进行处方前研究.方法 采用差示扫描量热法和傅里叶变换红外光谱法评价格列吡嗪与辅料是否相容;采用高效液相色谱法测定格列吡嗪和有关物质的质量分数.结果 差热分析结果表明,乳糖、硬脂酸镁和候选的pH调节剂对格列吡嗪的特征峰位有影响,影响范围在1～13℃之间;傅立叶红外光谱分析结果表明,格列吡嗪在特征区和指纹区内的特征峰没有发生明显的变化;液相分析结果显示,样品中的格列吡嗪质量分数在99.4％以上,有关物质质量分数在0.5％以下.结论 所选辅料、pH调节剂全部与格列吡嗪相容,对格列吡嗪的稳定性没有明显的影响,可用于处方研究当中.     

Impact of Surfactant and Surfactant-Polymer Interaction on Desupersaturation of Clotrimazole

The impact of surfactants on supersaturation of clotrimazole solutions was systematically evaluated. Four clinically relevant surfactants, sodium dodecyl sulfate, vitamin E TPGS, Tween 80, and docusate sodium were studied. The induction time for nucleation and rate of desupersaturation were determined at a supersaturation ratio of 90% amorphous solubility. Measurement was also performed in the presence of predissolved hydroxypropyl methylcellulose acetate succinate to study the effect of surfactant-polymer interaction on desupersaturation. The 4 surfactants showed varied effects on desupersaturation. From supersaturation maintenance perspective, in the presence of hydroxypropyl methylcellulose acetate succinate, the rank order for the 4 surfactants was found to be: docusate sodium > vitamin E TPGS > sodium dodecyl sulfate > Tween 80. Given the importance of maintaining supersaturation and varied effect of surfactants on nucleation kinetics and desupersaturation rate, a careful examination of active pharmaceutical ingredient, polymer and surfactant interaction on an individual basis is recommended for selecting an appropriate surfactant for use in amorphous solid dispersion formulation.