*Corresponding Author:
Richa Kumari
Sagar Institute of Technology and Management, Barabanki -225 001, India
E-mail: [email protected]
Date of Submission 17 February 2010
Date of Revision 18 August 2010
Date of Acceptance 7 November 2010
Indian J Pharm Sci, 2010, 72 (6): 785-787  

Abstract

A rapid and sensitive reverse phase RP-HPLC method is proposed for the estimation of tamsulosin hydrochloride in tablets. Tamsulosin hydrochloride was chromatographed on a reverse phase C18 column with a mobile phase consisting of acetonitrile and water in the ratio of 50:50 v/v. The mobile phase was pumped at a flow rate of 1.5 ml/min. The eluents were monitored at 214 nm. The retention time of the drug was 1.7 min. With this method, linearity was observed between area under curve and concentration of tamsulosin hydrochloride in the injected solution, in the range of 5 to 100 μg/ml. The method was found to be applicable for analysis of the drug in tablets. The results were validated statistically.

Keywords

RP-HPLC, stability indicating, tamsulosin HCl, validation

Tamsulosin Hydrochloride is chemically 5-{(2R)-2[{2-(2- ethoxyphenoxy)ethyl} amino]propyl}-2-methoxybenzene sulfonamide [1-5]. It is an α1 adrenoceptor blocking agent, exhibit selectivity for α1 receptors in the human prostate [6-8]. It brings about relaxation of prostatic and urethral smooth muscle. Literature survey reveals that the few techniques like HPLC, chiral LC method and non-aqueous potentiometric methods have been reported for the estimation of tamsulosin hydrochloride [9-11]. The focus of present study was to develop and validate a rapid, stable and economic RP-HPLC method for the estimation of tamsulosin hydrochloride in pharmaceutical dosage forms.

A binary gradient RP-HPLC with Shimadzu LC-10AT and LC-10AT VP series HPLC pumps, a 20 μl sample injection loop (manual) and SPD 10A VP UV/Vis absorbance detector was used for the study. The output signal was monitored and integrated using Shimadzu CLASS-VP Version 6.12 SP1 software.

A pure sample of tamsulosin hydrochloride was procured from Cipla. Tamsulosin hydrochloride tablets were purchased from a local pharmacy. The mobile phase consists of acetonitrile and water (50:50 v/v) was selected as it was found to ideally resolve the peaks of tamsulosin hydrochloride. The components of the mobile phase were pumped to the column at a flow rate of 1.5 ml/min that produced column back pressure of 195 kgf/cm2. The eluents were monitored at 214 nm having ambient column temperature. Acetonitrile and water used were of HPLC grade (Merck) and all other reagents were of AR grade. Mobile phase was prepared by mixing 500 ml of acetonitrile with 500 ml of water. The mobile phase was sonicated for 15 min and then it was filtered through a 0.45 μ membrane filter paper. About 10 mg of standard tamsulosin hydrochloride was accurately weighed and taken in 100 ml volumetric flasks separately and dissolved in the mobile phase. The volume was adjusted up to the mark with mobile phase to give stock solutions of 100 μg/ml. The standard stock solution was filtered through a 0.22 μ membrane filter paper. To determine the content of tamsulosin hydrochloride in conventional tablets, twenty tablets were weighed; their average weight was determined and finely powdered. The tablet powder equivalent to 10 mg of tamsulosin hydrochloride was weighed and transferred to a 100 ml volumetric flask and dissolved in 50 ml of mobile phase. The solution was ultrasonicated for 20 min and filtered through 0.22 μ membrane filter paper. The sample solution was further diluted with mobile phase to obtain sample solutions within the Beer Lambert’s range for the drug solution.

Linearity was determined by taking appropriate aliquots of the drug from the standard stock solution into a series of 10 ml volumetric flasks. It was diluted up to the mark with mobile phase in such a way that final concentrations of tamsulosin hydrochloride was in the range of 5-100 μg/ml. Triplicate dilutions of each concentration of the drug were prepared separately. From these triplicate solutions, 20 μl injections of each concentration of the drug were injected into the HPLC system two times separately and chromatographed under the optimized conditions. Evaluation of the drug was performed with the UV detector set at 214 nm and peak areas were recorded. The plots of peak area Vs respective concentration of tamsulosin HCl was found to be linear in the range of 5-100 μg/ml. The specificity of the RP-HPLC method was determined by complete separation of tamsulosin HCl as shown in (fig. 1).

Figure

Figure 1: Typical chromatogram of tamsulosin HCl

Also parameters like retention time (Rt), resolution (Rs) and tailing factor (T) of tamsulosin HCl were evaluated. The precision of the method was determined using the standard solutions of tamsulosinr

HCl. Standard solutions of concentrations, 20 and 40 μg/ml prepared in triplicate were used for studying the degree of precision of the developed method [12-15]. Repeatability of the assay was determined by duplicate injections of the prepared solutions in the same day for the intraday precision (Table 1). To check the accuracy of the proposed method, recovery studies were carried out by applying the standard addition method. A known amount of standard tamsulosin HCl corresponding to 80, 100 and 120% of the label claim was added to preanalysed sample of tablet dosage form. The recovery studies were carried out three times, at each level of recovery (Table 2).

Tablet formulation % Mean* ±SD % RSD
T1 99.68 0.64 0.642
T2 99.87 0.21 0.2102

Table 1: Statistical evaluation of tablet analysis.

Tablet formulation Type of recovery in % % Mean* SD % RSD
T1 80 99.73 0.368 0.369
  100 99.82 0.4262 0.4269
  120 99.8 0.1883 0.1886
T2 80 100.27 0.161 0.1605
  100 99.87 0.103 0.1031
  120 100.6 0.195 0.1938

Table 2: Statistical data for recovery studies.

The LOD and LOQ were separately determined (Table 3) based on the standard deviation of response of the calibration curve. The standard deviation of y-intercepts of regression lines and slope of the calibration curve may be used to calculate LOD and LOQ. LOD= 3.3×D/S and LOQ= 10×D/S, where, D is the standard deviation of the y-intercepts of regression line and S is the slope of the calibration curve.

Parameter     Result
Linearity range (μg/ml) 5-100
Regression coefficient (r2) ±SD 0.9997
Retention time (min) 1.7
Tailing factor 1.33
Theoretical plates 22011
Limit of detection (μg/ml) 0.019
Limit of quantification (μg/ml) 0.0575

Table 3: Validation and system suitability parameters

Optimization of mobile phase was performed based on resolution, asymmetric factor and peak area obtained. Overlain UV spectra of tamsulosin showed that drug absorbs at 214 nm. This wavelength was selected as the detection wavelength. Calibration curve was obtained by plotting peak area versus concentration and it was found to be linear.

The amount of drug found was between 99-101%. The sample recoveries in formulations were in good agreement with their respective label claim which suggested non-interference of formulation excipients in the estimation. The lower values of % RSD in (Table 2) indicate that the method is precise and accurate. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.0190 μg/ ml and 0.0575 μg/ml, respectively. Hence it can be concluded that the proposed method is a stability indicating simple, specific, precise and accurate which can be employed for the estimation of tamsulosin HCl in bulk and formulations.

Acknowledgements

The authors are thankful to Cipla Pharmaceuticals Ltd. for supplying the gift samples of pure tamsulosin hydrochloride.

References