Thermochemistry on ephedrine hydrochloride and N-methylephedrine hydrochloride

The crystal structures of ephedrine hydrochloride and N-methylephedrine hydrochloride have been determined by X-ray crystallography. The molar enthalpies of dissolution of the two compounds with various molalities were measured at T = 298.15 K in distilled water by means of isoperibol solution-reaction calorimeter, respectively. According to the theory of Pitzer, the molar enthalpies of dissolution of the two compounds at infinite dilution, ${\mathrm{\Delta }}_{\text{s}}{H}_{\text{m}}^{\infty }$, and Pitzer’s parameters ${\beta }_{\text{MX}}^{(0)L}\text{,}{\beta }_{\text{MX}}^{(1)L}\text{,}\text{and}{C}_{\text{MX}}^{{}^{\Phi }L}$, were obtained. Then the values of apparent relative molar enthalpies $({}^{\Phi }L)$, hydration heat, and relative partial molar enthalpies of the two compounds $({\overline{L}}_2)$ were derived from the experimental results of the enthalpies of dissolution of the two compounds. Finally, the ionic radius of the cations can be calculated from the data of the corresponding effective volume of the cations.     

Hydration of tri-n-hexyl amine hydrochloride,tri-n-octyl amine hydrochloride,tri-n-decyl amine hydrochloride and tri-n-dodecyl amine hydrochloride benzene solutions

Isopiestic equilibrations of THxA·HCl, TOA·HCl, TDA·HCl and TLA·HCl benzene solutions have been made in the concentration range from 0·02 to 0·13 mole/kg at different water activities and 25°C. The mean hydration number of the chloride ion at unit water activity was found to be 1·024±0·015 for the systems investigated. To determine the effect of water activity on the amine salt activity the results were treated on the basis of the Gibbs-Duhem equation and a simple linear relation obtained between salt and water activities. IR spectrophotometric measurements were performed to identify the nature of the hydrated species.     

Spectrophotometric determination of nicoumalone, acebutolol hydrochloride and procainamide hydrochloride

A sensitive spectrophotometric method is described for the determination of nicoumalone (NIC), acebutolol hydrochloride (ACBH) or procainamide hydrochloride (PAH) either in pure form or in pharmaceutical formulations. The method is based on the oxidative coupling reaction through the involvement of an aromatic primary amino group (released through reduction in NIC or hydrolysis in ACBH or existing free in PAH) in the drug with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in the presence of ferric chloride [Fe(III)]. The resulting chromophores are measured at 620 nm for NIC and ACBH and 580 nm for PAH. The concentration measurements are reproducible within a relative standard deviation of 1%.     

Stability-indicating assay for pivmecillinam hydrochloride and pivmecillinam hydrochloride capsules.

A high-pressure liquid chromatographic assay has been developed for pivmecillinam hydrochloride and pivmecillinam hydrochloride capsules. The method separates five reported degradation products and a number of esterified, related compounds. The accuracy of this method is comparable to the published ultraviolet assay and the relative standard deviation of a series of six replicate assays was better than +/- 0.7%.     

Fleroxacin hydrochloride hydrate

In the structure of the title compound, 4‐[3‐carboxy‐6,8‐di­fluoro‐1‐(2‐fluoro­ethyl)‐1,4‐di­hydro‐4‐oxo‐7‐quinolyl]‐1‐methyl­piperazinium chloride hydrate, C₁₇H₁₉F₃N₃O₃⁺·­Cl^?·­H₂O, the quinoline and its substituents, except for the fluoro­ethyl group, are coplanar, while the piperazinium moiety exists in a chair form. There are π–π‐stacking interactions between the quinoline rings, and intra‐ and intermolecular hydrogen bonds in the crystal.     

Sibutramine hydrochloride monohydrate

In the present work, the thermal decomposition of sibutramine hydrochloride monohydrate (SBT) (an appetite suppressant agent) was studied using differential scanning calorimetry (DSC) and thermogravimetry/derivative thermogravimetry (TG/DTG). Solid-state characterization was carried out by diffuse reflectance infrared fourier transform spectroscopy (DRIFT), scanning electron microscopy (SEM) and X-ray powder diffraction (XRPD). Isothermal and non-isothermal methods were employed to determine the kinetic data of decomposition process. From isothermal experiments, activation energy (Ea) can be obtained from slope of ln t versus 1/T, and the value obtained was 96.06 and 101.43 kJ mol⁻¹ in N₂ and air atmospheres, respectively. For non-isothermal method Ea can be obtained from plot of logarithms of heating rates, as a function of inverse of temperature, resulting in a value of 96.56 and 98.22 kJ mol⁻¹ in N₂ and air atmospheres, respectively. The compatibilities of several commonly used pharmaceutical excipients (microcrystalline cellulose, magnesium stearate, colloidal silicon dioxide, lactose monohydrate) and empty hard-gelatin capsules with SBT were evaluated using DSC. The 1:1 physical mixtures of these excipients with SBT showed physical interaction of the drug with magnesium stearate. On the other hand, DRIFT results did not evidence any chemical modifications.     

流动注射-化学发光方法测定盐酸萘甲唑林和盐酸氧甲唑林

H2SO4酸性条件下,甲醛对KMnO4-盐酸萘甲唑林(盐酸氧甲唑林)化学发光体系有较强的增敏作用,且强度与药物浓度呈良好的线性关系.据此,建立了采用KMnO4-甲醛体系测定制剂中盐酸萘甲唑林(盐酸氧甲唑林)的流动注射-化学发光分析法.在优化的实验条件下,盐酸萘甲唑林在1.0×10-8～7.0×10-6g/mL范围内呈良好的线性关系,检出限为8.69×10-9g/mL;盐酸氧甲唑林在5.0×10-8～1.0×10-5范围内呈线性关系,检出限为3.47×10-8g/mL.对浓度为1.0×10-6g/mL的盐酸萘甲唑林和盐酸氧甲唑林分别进行的11次平行测定,RSD分别为4.0%和4.1%.     

盐酸二甲双胍的毛细管电泳法快速测定

建立了毛细管电泳高频电导法快速测定片剂中盐酸二甲双胍的方法。考察了缓冲溶液、有机溶剂添加剂、毛细管长度以及分离电压和进样条件等因素对分离检测的影响。在最佳条件下5.0 min内即可实现盐酸二甲双胍分离检测,盐酸二甲双胍的线性范围为1.50μg/mL~130μg/mL,检出限为1.0μg/mL。该方法成功地测定了盐酸二甲双胍片剂中的盐酸二甲双胍。     

微流控芯片测定滴鼻液中的盐酸萘甲唑啉

建立了微流控芯片非接触电导检测法测定盐酸萘甲唑啉的分析方法。探讨了缓冲液种类、浓度,添加剂种类、浓度以及分离电压等因素对分离检测的影响。优化选择20 mmol/L H3BO3 10 mmol/L Tris(pH 7.5)缓冲溶液,2mmol/L-βCD添加剂,分离电压2.70 kV时,3 min内可实现盐酸萘甲唑啉的快速分离检测。在优化条件下,盐酸萘甲唑啉的线性范围为20~1.0×103μg/mL(r=0.995),检出限为5.0μg/mL(S/N=3),RSD为2.5%,加标回收率为98.3%~101%。