Diclofenac potassium is a non- steroidal anti-inflammatory drug and a prostaglandin (PG) synthetase inhibitor. The objective of this study was to develop a spectrophotometric method for the assay of diclofenac potassium. A series of diclofenac potassium solutions were prepared ranging from 200 ppm to 12.5 ppm. After preparation of a standard stock solution of 200 ppm in 100 ml of water, different dilutions were made (100ppm, 50ppm, 25ppm and 12.5ppm). At the wavelength 242nm, the absorbance of the standard preparation and dilutions was measured using a UV spectrophotometer. In this study a precise and accurate method was developed. The validation of the developed method for the assay of diclofenac potassium was done by various parameters that included linearity, accuracy test and precision. The method showed good reproducibility and good recovery with % RSD less than 2. The method was found to be simple, economical, rapid, specific, precise and accurate.
Keywords: Diclofenac Potassium; accuracy; linearity; regression equation; precision
Chemically diclofenac potassium is a monobasic potassium salt {2-[(2,6- Dichlorophenyl)amino]-benzene acetic acid} . as shown in Figure 1. . It belongs to a class of non-steroidal anti-inflammatory drugs (NSAIDs), and is effective against analgesia, fever and inflammation [1]. It is classified under prostaglandin (PG) synthetase inhibitors [2-4]. Diclofenac potassium acts by inhibiting © cyclooxygenase (COX) enzyme, the enzyme responsible for the formation of prostaglandins (PGs) such as PGF α. The 2 drug alleviates dysmenorrheic pain and no side effects have been reported [5]. It also restores exercise performance in women suffering from dysmenorrhea [6].
A method for the determination of diclofenac potassium individually or in combination with other drug preparations by High-performance liquid chromatography (HPLC) has been reported by Khatal LD et al [7]. A UV spectrophotometric method for the estimation of diclofenac potassium in a formulation has also reported [8]. Other assay methods for the determination of diclofenac potassium were Highperformance liquid chromatography (HPLC) method [9-11] and UV- spectroscopy method [12-13]. The present work describes the development of a validated UV-spectroscopy method that can quantify diclofenac potassium from a dosage form. The present diclofenac
Materials and Methods: A standard diclofenac potassium sample was supplied by Abbot Pharmaceutical Laboratories (Pakistan limited) in bulk.
UV visible spectrophotometer Shimadzu double beam 1601 was used to measure spectra. The solvent used was water for the assay.
A series of diclofenac potassium solutions were prepared ranging from 200 ppm to 12.5 ppm accurately by dissolving the active diclofenac potassium in water. The diclofenac potassium solution was scanned in the UV regions. The wavelength maximum (λmax) was observed at 242nm.
A series of diclofenac potassium solutions were prepared ranging from 200 ppm to 12.5 ppm. After preparation of a standard stock solution of 200 ppm in 100 ml of water, different dilutions were made (100ppm, 50ppm, 25ppm and 12.5ppm). At the wavelength 242nm, the absorbance of the standard preparation and dilutions was measured using the UV spectrophotometer. The quantity in mg, of diclofenac potassium was determined.
The validation of developed method for the assay of diclofenac potassium was done by various parameters that included linearity, accuracy test and precision.
Linearity was determined in the range of −1 12.5-200 μg mL . Least square linear regression analysis was applied to Peak area versus concentration of diclofenac potassium. A linear regression line was obtained with correlation coefficient (R2 > 0.9993). The regression equation for active (what is active here?) is displayed in Figure 2.
8
Accuracy of the developed method for the y = 0.011x + 0.029 2.5 R² = 0.999 2 1.5 abs 1 Linear (abs) 0.5 0 0 100 200 300 assay of diclofenac potassium was determined as the percentage of recovery of known amounts of diclofenac potassium at spike concentration that was 40, 50 and 60 mg mL−1. Every sample was taken five times and result range was 99.8%- 100.20%, (Table 2) The method has a high degree of accuracy and this was indicated by high recovery.
Figure 2: Linearity of diclofenac potassium
Repeatability (i.e. intra-day precision and inter day precision) of the developed method for the assay of diclofenac potassium was determined. It was defined as relative standard deviation % RSD. Five different dilutions of diclofenac potassium (200ppm, 100ppm, 50ppm, 25ppm and 12.5ppm) in the linear range were analyzed in the same day (intra-day precision) and two consecutive days (inter-day precision); every sample was taken five times. Good precision was observed in both intra and inter-day %RSD values, the values were in the range of 0.51-1.92% (Table 3).
% Conc Drugs %RSD Recovery 80% 1.20 100.20 Diclofenac 100% 1.20 100.00 potassium 120% 1.30 99.98 200 2.334 100 1.23 50 0.61 25 0.32 12.5 0.154 Table No. 1 : Absorbance of drug in different concentration Table 2: Accuracy of diclofenac potassium The insignificant results showed no remarkable difference in inter and intraday precision.
In concentration range of 12.5-200 μg/ml the calibration curve was linear for diclofenac potassium with correlation coefficient of 0.9993. The precision both intra and inter-day and accuracy of the proposed method was determined and validated statistically. The method showed good reproducibility and good recovery with % RSD less than 2. The method was found to be simple, economical, rapid, specific, precise and accurate. This method can be successfully applied for the routine analysis of diclofenac potassium. By performing accuracy studies, the accuracy of the proposed method was confirmed, and the results were acceptable. The precision of the proposed method was confirmed by performing intraday and inter day precision. The method for the determination of diclofenac potassium was validated according to ICH guidelines. This 9 Inter day and intraday precision of diclofenac potassium Table No. 3: Precision of Diclofenac Potassium method can be adapted for routine assay.
The intra-run and inter-run variability and accuracy results were in the acceptable limit according to ICH guidelines. The short analysis time (< 5min) enables its application in routine and quality control analysis of finished products.
ug −1 mL Inter Drugs %RSD %Recovery 200 0.55 100 1.26 50 1.91 Diclofenac 25 1.79 potassium 12.5 1.12