Separation and quantification of ropinirole and some impurities using capillary liquid chromatography

Effect of Antiadherents on the Physical and Drug Release Properties of Acrylic Polymeric Films

Antiadherents are used to decrease tackiness of a polymer coating during both processing and subsequent storage. Despite being a common excipient in coating formulae, antiadherents may affect mechanical properties of the coating film as well as drug release from film-coated tablets, but how could addition of antiadherents affect these properties and to what extent and is there a relation between the physical characteristics of the tablet coat and the drug release mechanisms? The aim of this study was to evaluate physical characteristics of films containing different amounts of the antiadherents talc, glyceryl monostearate, and PlasACRYL(TM) T20. Eudragit RL30D and Eudragit RS30D as sustained release polymers and Eudragit FS30D as a delayed release material were used. Polymer films were characterized by tensile testing, differential scanning calorimetry (DSC), microscopic examination, and water content as calculated from loss on drying. The effect of antiadherents on in vitro drug release for the model acetylsalicylic acid tablets coated with Eudragit FS30D was also determined. Increasing talc concentration was found to decrease the ability of the polymer films to resist mechanical stress. In contrast, glyceryl monostearate (GMS) and PlasACRYL produced more elastic films. Talc at concentrations higher than 25% caused negative effects, which make 25% concentration recommended to be used with acrylic polymers. All antiadherents delayed the drug release at all coating levels; hence, different tailoring of drug release may be achieved by adjusting antiadherent concentration with coating level.

Box-Behnken supported validation of stability-indicating high performance thin-layer chromatography (HPTLC) method: An application in degradation kinetic profiling of ropinirole

Stability-indicating high-performance thin-layer chromatographic (HPTLC) method for the analysis of ropinirole HCl was developed and validated as per the ICH guidelines. The method employed the mobile phase and toluene-ethyl acetate-6 M ammonia solution (5:6:0.5, v/v/v) was optimized with the help of a design expert. Densitometric analysis of ropinirole HCl was carried out in the absorbance mode at 250 and 254 nm. Compact spots for ropinirole HCl were found at R f value of 0.58 ± 0.02. The linear regression analysis data for the calibration plots showed R (2) = 0.9989 ± 0.0053 with a concentration range of 100-3000 ng spot(-1). The method was validated for precision, accuracy, ruggedness, robustness, specificity, recovery, limit of detection (LOD) and limit of quantitation (LOQ). The LOD and LOQ were 12.95 and 39.25 ng spot(-1) respectively. Drug was subjected to acidic, alkaline, oxidative, dry heat, wet heat and photo degradation stress. All the peaks of degradation products were well resolved from the standard drug peak with significant difference of R f. The acidic and alkaline stress degradation kinetics of ropinirole, were found to be in first order, showing high stability (t 1/2, 146.37 h(-1); t 0.9, 39.11 h(-1)) in the acidic medium and low stability (t 1/2, 97.67 h(-1); t 0.9, 14.87 h(-1)) in the alkaline environment.

Spectrophotometric estimation of ropinirole hydrochloride in tablets

A simple, sensitive, rapid, accurate and precise spectrophotometric method has been developed for estimation of ropinirole hydrochloride in bulk and tablet dosage forms. Ropinirole hydrochloride shows maximum absorbance at 250 nm with molar absorptivity of 8.703×10³ l/mol.cm. Beer's law was obeyed in the concentration range of 5-35 μg/ml. Results of analysis were validated statistically and by recovery studies.

Highly sensitive and selective spectrophotometric and spectrofluorimetric methods for the determination of ropinirole hydrochloride in tablets

Three sensitive, selective, accurate spectrophotometric and spectrofluorimetric methods have been developed for the determination of ropinirole hydrochloride in tablets. The first method was based on measuring the absorbance of drug solution in methanol at 250 nm. The Beer's law was obeyed in the concentration range 2.5-24 microg ml(-1). The second method was based on the charge transfer reaction of drug, as n-electron donor with 7,7,8,8-tetracyanoquinodimethane (TCNQ), as pi-acceptor in acetonitrile to give radical anions that are measured at 842 nm. The Beer's law was obeyed in the concentration range 0.6-8 microg ml(-1). The third method was based on derivatization reaction with 4-chloro-7-nitrobenzofurazan (NBD-Cl) in borate buffer of pH 8.5 followed by measuring the fluorescence intensity at 525 nm with excitation at 464 nm in chloroform. Beer's law was obeyed in the concentration range 0.01-1.3 microg ml(-1). The derivatization reaction product of drug with NBD-Cl was characterized by IR, 1H NMR and mass spectroscopy. The developed methods were validated. The following analytical parameters were investigated: the molar absorptivity (epsilon), limit of detection (LOD, microg ml(-1)) and limit of quantitation (LOQ, microg ml(-1)), precision, accuracy, recovery, and Sandell's sensitivity. Selectivity was validated by subjecting stock solution of ropinirole to acidic, basic, oxidative, and thermal degradation. No interference was observed from common excipients present in formulations. The proposed methods were successfully applied for determination of drug in tablets. The results of these proposed methods were compared with each other statistically.

Isolation and characterization of some potential impurities in ropinirole hydrochloride

Three impurities in ropinirole hydrochloride drug substance at levels approximately 0.06-0.15% were detected by reverse-phase high performance liquid chromatography (HPLC). These impurities were isolated from the drug substance. These impurities were analyzed using reverse-phase HPLC. Based on the spectral data (IR, NMR and MS), structures of these impurities were characterized as 4-[2-(propylamino) ethyl]-1,3-dihydro-2H-indol-2-one hydrochloride (impurity-A), 5-[2-(diropylamino) ethyl]-1,4-dihydro-3H-benzoxazin-3-one hydrochloride (impurity-B) and 4-[2-(diropylamino) ethyl]-1H-indol-2,3-dione hydrochloride (impurity-C). Synthesis of these impurities is discussed.

An overview of the recent trends in development of HPLC methods for determination of impurities in drugs

An extensive survey of the literature published in various analytical and pharmaceutical chemistry related journals has been conducted and the high-performance liquid chromatography (HPLC) methods which were developed and used for determination of process-related impurities in drugs have been reviewed. This review covers the time period from 1995 to 2001 during which around 450 analytical methods including all types of chromatographic and hyphenated techniques were reported. HPLC with UV detection was found to be the technique of choice for many workers and more than 200 methods were developed using LC-UV alone. A critical analysis of the reported data has been carried out and the present state-of-art of HPLC for determination of impurities of analgesic, antibiotic, anti-viral, anti-hypertensive, anti-depressant, gastro-intestinal and anti-neoplastic agents has been discussed.