Development and Validation of HPTLC Method for Determination of Edaravone in Bulk and in Injectable Dosage Form
A simple, rapid, reliable and accurate high performance thin layer chromatography method has been developed for the estimation of Edaravone in bulk and pharmaceutical dosage form. The chromatographic development was carried out on aluminum plates, pre-coated with silica gel 60 F254, using a mixture of Toluene: Methanol (6:â€‰4â€‰v/v) as mobile phase. Detection was carried out densitometrically at 254â€‰nm. Theð‘…fvalue of analyte was found to be0.66±0.02. The method was validated with respect to linearity, accuracy, precision, limit of detection, limit of quantification and specificity. The linear regression analysis data for the calibration plots showed a good linear relationship with Ÿ2=0.9995 in the concentration range 200–600â€‰ng/spot. The % assay (Mean ± S.D.) was found to be100.27±0.72. Accuracy of the method was accessed by percentage recovery and found to be99.77±0.71%. The method is new, simple and economical for routine estimation of edaravone in bulk, pre-formulation studies and pharmaceutical formulation rapidly at low cost in routine analysis.
Keywords: Edaravone, HPTLC, Pharmaceutical dosage form
Edaravone [EDA] is a neuroprotective agent used for the purpose of aiding neurological recovery following acut ebrain ischemia and subsequent cerebral infarction. Chemically, it is 3-Methyl-1-phenyl-2-pyrazolin-5-one. . It is a strong novel free radical scavenger, was developed by Mitsubishi Tanabe Pharma Corporation (Osaka, Japan). It acts as a potentantioxidant, protecting against oxidative stress and neuronal apoptosis Furthermore, edaravone has anti-apoptotic, anti-necrotic, and anti-inflammatory cytokine effects, as well as scavenging free radicals in cardiovascular diseases and stroke, showing protective effects in the heart, vessel, and brain in experimental studies [2-5] Different methods have been reported for the determination of EDA in the bulk drug, in the dosage forms and in biological samples. HPLC [6-7] and potentiometric titrations  methods are available for determination of the analyte in bulk drug and formulation. RP-HPLC , RP-HPTLC  and LC-MS/MS  methods are reported for determination in biological samples.
The literature survey revealed that HPTLC method is not reported for determination of EDA in bulk and pharmaceutical dosage forms.
The present study describes the development and validation of a simple, specific, sensitive, accurate, precise, and economical HPTLC method for determination of EDA in bulk and injectable dosage form. The proposed method is optimized and validated as per the International Conference on Harmonization (ICH) guidelines [12,13].
Fig 1: Edaravone
2.1 Reagents and chemicals
Edaravone was kindly gifted from Sun Pharmaceuticals, Vadodara, Gujarat, India. Edaravone injection was obtained from commercial sources within their shelf life period. All the reagents and solvents used were of analytical grade and obtained from Merck Chemicals.
Chromatography was performed on 20cm×10cm aluminum foil plates precoated with 0.2mm layers of silica gel 60 F254 (E. Merck, Germany). The plates were prewashed with methanol and water mixture, dried in the current of dry air and activated at 120°C for 5min. Samples were applied as bands 6mm wide, by use of a CAMAG (Switzerland) Linomat 5 applicator with a CAMAG microliter syringe. A constant application rate of 150nLs−1was employed. Linear ascending development was performed in a twin-trough glass chamberwith mobile phase consisted of toluene: methanol (6:4 v/v), which gave sharp and symmetrical peak withð‘…f0.66 + 0.02. The optimized chamber saturation time was 15 min at room temperature (25âˆ˜C±2âˆ˜C) and relative humidity60%±5%. After development, the plates were dried. Densitometric scanning, at 254 nm, was performed with a CAMAG TLC scanner 4 in absorbance mode. The source of radiation was a deuterium lamp emitting a continuous UV spectrum in the range of 190–400 nm.
An accurately weighed quantity of 10â€‰mg EDA was transferred to 10â€‰mL volumetric flasks, dissolved in methanol, and volume was made up to mark with the same solvent to obtain a working standard having concentration 1000â€‰ngâ€‰μL−1.
Initially, different ratios of methanol and toluene were tried, but tailing of spots was observed. Finally, the mobile phasecomprising of toluene:â€‰methanolâ€‰(6:â€‰4â€‰v/v) gives good resolution, sharp and symmetrical peak withð‘…ð¹value of 0.63 at 254â€‰nm.
Figure 2: Chromatogram of standard Edaravone: (Rf = 0.63).
3. Result and discussion
Validation of HPTLC method:
The proposed method was validated as per the ICH guidelines in terms of its linearity, accuracy, specificity, intraday and interday precision, limit of detection (LOD), and limit of quantification (LOQ).
The amount of standard solution equivalent to 200-600 ng/spot of EDA was spotted on the prewashed TLC plates. The plates were developed, dried and scanned as described above. The calibration plot was constructed by plotting peak areas against the corresponding concentrations (ng/spot) of EDA. The linearity of response for EDA was assessed in the concentration range 200-600 ng/spot in terms of slope, intercept and correlation coefficient values. The calibration plot showed the correlation coefficient (r2 = 0.999), the intercept (5.838) and the slope (703.3) over the concentration range of 200-600 ng/spot (Fig. 2). The results of regression analysis are shown inTable 1.
The limit of detection (LOD) and the limit of quantification (LOQ) of the drug were derived by calculating the signal-to-noise ratio (S/N, i.e., 3.3 for LOD and 10 for LOQ) using the following equations designated by International Conference on Harmonization (ICH) guidelines
LOD = 3.3 × σ/S
LOQ = 10 × σ/S
Where, σ = the standard deviation of the response and S = slope of the calibration curve.
Suitable levels of precision and accuracy have been demonstrated between the upper and lower concentration limit of linearity under study.
The intra-day and inter-day variation for the determination of EDA was carried out at three different concentration levels 400, 600, 800 ng/spot. Intra-day variations were assessed by analyzing these concentrations in triplicate within a day and inter-day variation was assessed by using the same concentration of drug and analyzing it different days and time.
The accuracy of the method was determined by the use of standard addition at three different levels. The pre analyzed sample solution of 400 ng/spot of EDA was spiked with extra amount equivalent to 80 %, 100 % and 120 % of the standard edaravone and the mixtures were analyzed by the proposed method. The experiment was conducted in triplicate. When these solutions were analyzed the recoveries were found to be within acceptable limits (Table 1).
The mobile phase was optimized and it showed good result. There was no interference of diluents and other constituent’s in determining peak purity. This method is specific.
A new HPTLC method has been developed for the identification and quantification of EDA. Low cost, faster speed, and satisfactory precision and accuracy are the main features of this method. The method was successfully validated as per ICH guidelines and statistical analysis proves that the method is sensitive, specific, and repeatable. It can be conveniently employed for routine quality control analysis of EDA as bulk drug and in marketed injectable formulation.
The authors express their gratitude to Sun Pharmaceuticals Vadodara, Gujarat, India for providing a gift sample of Edaravone, the Management of Pioneer Pharmacy Degree College, Vadodara, Gujarat, India, and Anchrom Test lab Pvt. Ltd, Mumbai, Maharastra, India, for providing the necessary facilities.