An effective and sensitive stability-indicating chromatographic approach based on HPLC for silodosin assay

Er and Erk Journal of Analytical Science and Technology (2016) 7:20 DOI 10.1186/s40543-016-0100-y Journal of Analytical Science and Technology RESEARCH ARTICLE Open Access An effective and sensitive stabilityindicating chromatographic approach based on HPLC for silodosin assay Engin Er* and Nevin Erk Abstract Background: A stability-indicating reversed-phase high-performance liquid chromatography (HPLC) method with a high sensitivity was developed for the determination of silodosin (SIL) in the presence of hydrochlorothiazide (HCT) as an internal standard. Methods: Chromatographic separation of SIL and IS were successfully achieved on an Agilent ZORBAX CN column with an isocratic mobile phase composed of a mixture of methanol:acetonitrile:ammonium acetate (pH 4.0; 0.015 M) (40:30:30, v/v/v) at a flow rate of 1.3 mL min−1. The drugs were quantified using a photodiode array detector set at a wavelength of 270 nm. The reversed-phase HPLC method has been validated as per International Conference on Harmonisation (ICH) of Technical Requirements for Registration of Pharmaceuticals for Human Use guidelines to determine SIL in pharmaceutical dosage form. Results: The proposed method showed a good linearity in the concentration range of 4.0–600.0 μM with a lower detection limit of 85.0 nM under optimized conditions. The statistical performance of the fully validated HPLC method was compared to our developed sensitive spectrofluorimetric method, and the performance results of the proposed HPLC method were considerably satisfactory. The validated method was successfully applied to quantify the SIL in capsules, and the corresponding recovery value was found to be 99.5 %. Conclusions: The validated HPLC method may be a promising alternative analytical tool for routine analysis of SIL in pharmaceutical samples. Keywords: Silodosin, HPLC, Spectrofluorimetry, Determination, Validation Background Silodosin (SIL) is a new selective α1-adrenoreceptor antagonist in alpha-blocker class with a high pharmacologic selectivity as shown in Scheme 1 (Sweetman 2009). α1-adrenoreceptor antagonists were widely used in the treatment of lower urinary tract symptoms resulting from benign prostatic hyperplasia (BPH). BPH is a common disorder of the urogenital tract for at least 50 % of men aged over 50 years (Goi et al. 2015). At this point, SIL has been proven to advanced relieve the muscles in the prostate by reducing lower urinary tract symptoms related to BPH (Goi et al. 2015; Yoshida et al. 2007). Therefore, a reliable and precise determination method * Correspondence: Department of Analytical Chemistry, Faculty of Pharmacy, Ankara University, Tandoğan, 06100 Ankara, Turkey is highly important for the analysis of SIL in pharmaceutical or clinical samples. The literature revealed that various analytical methods have been reported to determine the SIL in pharmaceutical or clinical samples including UV spectrophotometry (Jahan and Malipatil 2014b), spectrofluorimetry (Bhamre and Rajput 2014), high-performance liquid chromatography (HPLC) (Jahan and Malipatil 2014a ; Aneesh and Rajasekaran 2012; Vali et al. 2012), high-performance thin-layer chromatography (Sayana et al. 2012), ultra high-performance liquid chromatography (UHPLC) (Shaik et al. 2014; Prasad et al. 2012) and liquid chromatographytandem mass spectrometry (LC-MS/MS) (Zhao et al. 2009) and electrochemicalsensing (Er et al. 2015) methods. Recently, the authors have attached great importance develop the sensitive and reliable analytical methods for © 2016 The Author(s). Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Er and Erk Journal of Analytical Science and Technology (2016) 7:20 Page 2 of 8 from J.T. Baker (Phillipsburg, NJ) with HPLC grade. The other chemicals and reagents were purchased from Sigma-Aldrich Company (Germany) and were of analytical grade. All solutions and mobile phase were prepared with ultrapure water using Waters Milli-Q Plus purification system. Scheme 1 Molecular structure of SIL determination of biological and drug molecules at nano-molar levels. In this point, we thought that an effective and highly sensitive analytical tool such as HPLC is required with a short response time for SIL assay. In addition, the spectrophotometric approach is also preferred especially in the detection of drug molecules due to its many advantages such as cost effectiveness, easy operation, high sensitivity and repeatability, rapid response time and low detection limit (Tekkeli and Önal 2011; Walash et al. 2013). The present study has indicated accurate and efficient analytical methods based on reversed-phase HPLC and spectrofluorimetry for the determination of SIL in a pharmaceutical sample. Methods Chemicals and reagents SIL powder was gifted from Recordati Pharm. Company. Urorec® (containing 8.0 mg SIL per capsule) capsules were purchased from a local market in Ankara, Turkey. The internal standard (IS) was used as a hydrochlorothiazide (HCT) in HPLC measurements. The methanol and acetonitrile solutions for HPLC studies were purchased Instrumentation and conditions HPLC analyses were performed by an Agilent 1100 series LC system (Agilent Technologies, Wilmington, USA) equipped with an Agilent series G-1315B diode-array detector (DAD), G-1313A ALS autosampler, G1311A Quat pump and G1379A degasser. Chromatographic separation was performed on a Agilent ZORBAX CN column (reversed-phase) (150 mm × 4.6 mm, 5 μM) in isocratic mode. Data were collected and processed by the use of Agilent ChemStation. The mobile phase consisted of a mixture of aqueous 0.015 M ammonium acetate (pH 4.0):methanol:acetonitrile in the ratio (30:40:30, v/v/v). The pH of the ammonium acetate was adjusted to 4.0 by addition of NaOH and HCl, and the mixture was pumped at 25 °C with a flow rate of 1.3 mL min−1. The detection was achieved at 270 nm, and the injection volume was 10 μL. The mobilephase mixture was filtered through a 0.45μm membrane filter (Millipore, Bedford, MA) and degassed under ultrasonic bath before HPLC analysis. The quantification of SIL was based on peak area ratio using IS. Fluorescence spectra were measured by Agilent Cary Eclipse spectrofluorometer (CA, USA) equipped with a Xenon flash lamp. The slit widths for excitation and emission monochromators were fixed at 10 nm. All measurements were performed in a 1.0cm quartz cell at room temperature (25 °C). Fig. 1 Effect of pH on the fluorescence intensity of SIL (a) in methanol:water (1:1, v/v). Effect of the excitation wavelength on the fluorescence intensity of SIL in pH 6.0 phosphate buffer (b) Er and Erk Journal of Analyti (...truncated)