Stability Indicating Reversed-Phase High Performance Liquid Chromatography Method for Determination of Impurities in Ofloxacin Tablet Formulations

A gradient reversed-phase high performance liquid chromatography (RP-HPLC) method was developed for separation and quantitation of impurities in pharmaceutical dosage form of ofloxacin tablets. The developed method was a stability indicating test method for estimation of related impurities generated during synthesis, formulation, and storage of ofloxacin tablets. Forced degradation studies were performed on ofloxacin tablets including acid hydrolysis (5.0 M hydrochloric acid), base hydrolysis (5.0 M sodium hydroxide), oxidation (30% hydrogen peroxide), heat (105°C) humidity degradation 25°C/92% RH/119 b & 40 min, and photolytic degradation (2600 Lux/119 h & 40 min). From the degradation study, the degradation was found between 0–15%. Limit of detection and limit of quantification were established in terms of percentage for all potential impurities. The recovery studies were conducted on finished dosage samples (tablets) for all potential impurities and the average percentage recovery was ranged from 90.8 to 104.2. Placebo interference was verified by taking the placebo (composition of excipients) equivalent to weight in portion of test preparation and no interference was observed. The method was validated and found to be linear, accurate, precise, specific, robust, and reliable. The developed method was established in accordance to ICH guidelines.     

人工神经网络紫外分光光度法同时测定去痛片组分含量

用BP人神经网络处理复方制剂去痛片的紫外吸收光谱数据,达到了对其各组分含量进行同时测定的目的。通过对网络结构和参数的优化,提高了预报的准确度。     

Thermal desorption counter‐flow introduction atmospheric pressure chemical ionization for direct mass spectrometry of ecstasy tablets

A novel approach to the analysis of ecstasy tablets by direct mass spectrometry coupled with thermal desorption (TD) and counter‐flow introduction atmospheric pressure chemical ionization (CFI‐APCI) is described. Analytes were thermally desorbed with a metal block heater and introduced to a CFI‐APCI source with ambient air by a diaphragm pump. Water in the air was sufficient to act as the reactive reagent responsible for the generation of ions in the positive corona discharge. TD‐CFI‐APCI required neither a nebulizing gas nor solvent flow and the accompanying laborious optimizations. Ions generated were sent in the direction opposite to the air flow by an electric field and introduced into an ion trap mass spectrometer. The major ions corresponding to the protonated molecules ([M + H]⁺) were observed with several fragment ions in full scan mass spectrometry (MS) mode. Collision‐induced dissociation of protonated molecules gave characteristic product‐ion mass spectra and provided identification of the analytes within 5 s. The method required neither sample pretreatment nor a chromatographic separation step. The effectiveness of the combination of TD and CFI‐APCI was demonstrated by application to the direct mass spectrometric analysis of ecstasy tablets and legal pharmaceutical products. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis and characterization of new copolymers of ethyl methacrylate grafted on tapioca starch as novel excipients for direct compression matrix tablets

In last years, the introduction of new materials for drug delivery matrix tablets has become more important. This paper evaluates the physicochemical and mechanical properties of new graft copolymers of ethyl methacrylate (EMA) on tapioca starch (TS) and hydroxypropylstarch (THS), synthesized by free radical polymerization and dried in a vacuum oven (OD) or freeze-dried (FD). Infrared and ¹³C NMR spectroscopies confirm the change of chemical structure of the copolymers and X-ray diffraction shows up the higher amorphization of copolymers respect to the carbohydrates. Particle size analysis and SEM indicate that graft copolymerization leads to an increase of particle size and a more irregular shape. Graft copolymerization implies decrease of density and moisture content values. Heckel equation shows that copolymers have less densification by particle rearrangement and fragmentation than carbohydrates. Concerning the drying methods, FD products have larger plasticity and lower elasticity than OD copolymers. Graft copolymerization produces a decrease of the applied pressure necessary to obtain tablets, ejection force and friction work. Furthermore, graft copolymers show longer disintegration time than tablets from raw starches. These qualities suggest that these copolymers could be used as excipients in matrix tablets obtained by direct compression, and with a potential use in controlled release.     

Analysis of quinocide in unprocessed primaquine diphosphate and primaquine diphosphate tablets using gas chromatography–mass spectrometry with supersonic molecular beams

Malaria is one of the most widespread and deadly diseases on the planet. Every year, about 500 million new cases are diagnosed, and the annual death toll is about 3 million. Primaquine has strong antiparasitic effects against gametocytes and can therefore prevent the spread of the parasite from treated patients to mosquitoes. It is also used in radical cures and prevents relapse. Consequently, primaquine is an often-used drug. In this study the separation of unprocessed primaquine from the contaminant quinocide based on gas chromatography–mass spectrometry with supersonic molecular beam (SMB) is presented and 7.5 mg primaquine diphosphate tablets were analyzed. We present a novel method for fast determination of quinocide which is an isomer of primaquine as the main contaminant in unprocessed primaquine and in its medical form as tablets by gas chromatography–mass spectrometry with SMB (also named supersonic GC–MS). Supersonic GC–MS provides enhanced molecular ion without any ion source related peak tailing plus extended range of compounds amenable for GC–MS analysis. In addition, major isomer mass spectral effects were revealed in the mass spectra of primaquine and quinocide which facilitated the unambiguous identification of quinocide in primaquine tablets. Fast GC–MS analysis is demonstrated with less then 2 min elution time of the drug and its main contaminants.     

统计模拟分光光度法在增效联磺片分析中应用的研究

本文应用统计模拟分光光度法建立了同时测定增效联磺片三组分含量的分析方法。用全面交叉组合法安排实验，获得有限但足够的实验数据，再用逐步回归法构造在不同波长下吸光度与组分浓度经验关系的“最优”数学模型，用全组合检索法寻优求出未知样品诸组分的含量。为认证此方法用均匀设计安排回收率试验，并对含量测定结果进行了方差分析，结果均令人满意．     

人工神经网络紫外分光光度法测定息喘灵片多组分体系的研究

介绍了人工神经网络（ＡＮＮ）原理，详细讨论了网络参数的选择及其对预报的影响。将该技术应用于息喘灵片三组分体系的预报测定并取得满意结果。     

Assay of anti-coagulant drug warfarin sodium in pharmaceutical formulation and human biological fluids by square-wave adsorptive cathodic stripping voltammetry

The cyclic voltammogram of the anti-coagulant drug warfarin sodium at the hanging mercury drop electrode exhibited a well-defined single two-electron irreversible peak over the pH range 4-7, which may be attributed to the reduction of the CO double bond of the drug molecule. Based on the interfacial adsorptive character of the drug onto the mercury electrode surface, a square-wave cathodic stripping procedure was optimized for its trace determination. The calibration plot was linear over the concentration range of 5×10⁻⁹ to 4×10⁻⁷ M warfarin sodium in Britton-Robinson (B-R) buffer of pH 5, with limits of detection and quantitation of 6.5×10⁻¹⁰ and 2.1×10⁻⁹ M warfarin sodium, respectively. The proposed procedure was successfully applied for assay of warfarin sodium in its pharmaceutical formulation “hemofarin tablets”, human serum and urine without the necessity for sample pretreatment or time-consuming extraction or evaporation steps, prior to assay of the drug. Limits of detection of 1.1×10⁻⁹ and 1.3×10⁻⁸ M warfarin sodium were achieved, while limits of quanitation of 3.7×10⁻⁹ and 4.3×10⁻⁸ M warfarin sodium were estimated in human serum and urine, respectively. The pharmacokinetic profiles of the drug were studied and the estimated pharmacokinetic parameters were favorably compared with those reported in literature.     

Study on the bioavailability of puerarin from Pueraria lobata isoflavone self-microemulsifying drug-delivery systems and tablets in rabbits by liquid chromatography-mass spectrometry

To evaluate the bioavailability of puerarin from Pueraria lobata isoflavone self-microemulsifying drug delivery systems (SMEDDS) and Yufengningxin tablets, a rapid and specific liquid chromatography--mass spectrometric method was developed and validated to determine puerarin in rabbit serum. The analyte was extracted from serum samples by precipitating the serum proteins, separated on a Diamonsil C(18) column and detected by mass spectrometry with an electrospray ionization interface. 4-Hydroxybenzaldehyde was used as the internal standard. The method has a limit of quantitation of 10 ng/mL using 200 microL serum. The intra-day relative standard deviations (RSDs) ranged from 3.7 to 6.9% and inter-day RSDs were within 6.5%. After administration of SMEDDS and tablets to rabbits, a significant difference was observed in main pharmacokinetic parameters of t(max), C(max) and AUC(0--infinity) between SMEDDS and tablets, and a 2.2-fold increase in the relative bioavailability of puerarin was observed with the SMEDDS compared with Yufengningxin tablets. It was concluded that the absorption of puerarin from Pueraria lobata isoflavone SMEDDS was enhanced.