INTRODUCTION:

Iloperidone, is chemically (1-[4-[3-[4-(6-fluoro-1,2-benzisoxazol-3-yl)-1-piperidinyl]propoxy]-3-methoxy phenyl]ethanone) (Figure 1) with a molecular formula C₂₄H₂₇FN₂O₄ and molecular weight 426.48. Iloperidone is a second generation atypical antipsychotic agent recently approved by United States Food and Drug Administration and is indicated for the acute treatment of schizophrenia in adults. Iloperidone is a white to off-white finely crystalline powder. It is practically insoluble in water, very slightly soluble in 0.1 N HCl and freely soluble in chloroform, ethanol, methanol, and acetonitrile. It is commercially available in the form of oral tablets in seven different strengths viz. 1mg, 2mg, 4mg, 6mg, 8mg, 10mg and 12mg¹.

Figure 1:Chemical structure of Iloperidone

From the literature survey, it was found that Iloperidone was estimated by few analytical methods such as reversed-phase high-performance liquid chromatographic (RP-HPLC) method in pharmaceutical dosage form ^2-7 and liquid chromatographic-mass spectrometric (LC-MS) method in biological fluids⁸. HPLC-NMR and HPLC-NMR-MS methods for identification of in vivo and in vitro metabolites of iloperidone have also been reported and UV Spectrophotometric method⁹. However, quantification of Iloperidone in pharmaceutical dosage forms by UV spectrophotometric method using economical solvent like 0.1NHCL has not yet reported in the literature. Therefore, an attempt was made to develop a simple, economic, accurate and sensitive UV spectrophotometric method for the estimation of Iloperidone in bulk and tablet dosage form. In the present study, UV analysis of Iloperidone was performed in 0.1N HCL. The spectrum was recorded from 200 nm to 400 nm and the quantitative analysis was carried out at 229.5 nm. The method was validated as per ICH guidelines and can be applied for the determination of Iloperidone in routine analysis.

MATERIAL AND METHODS:

Instrumentation:

The spectrophotometric measurements were carried out using Elico UV/Visible double beam spectrophotometer SL-210 with 1 cm matched quartz cells.

Chemicals:

Pharmaceutical grade of Iloperidone was procured from MSN Laboratories ltd., Hyderabad, India. All the chemicals used were of analytical reagent grade of Merck (Germany) unless otherwise specified. 0.1N HCL was used to prepare all solutions. Freshly prepared solutions were always employed. Formulation of Iloperidone (ILOSURE tablets) was supplied from local pharmacy.

Preparation of Standard solution:

Standard stock solution was prepared by dissolving 10 mg of Iloperidone in 100 mL of 0.1N HCL to obtain a concentration of 100 μg/mL solution. It was heated gently so as to dissolve completely and was used as working standard solution.

Method development:

Aliquot of working standard solution was further diluted in a 10 ml volumetric flask with 0.1N HCL to get concentration of 10μg/mL and it was scanned between 200-400 nm which showed the maximum absorbance ( λ max) at 229.5 nm (Figure 2). The same l_maxwas used for the further measurement of the Iloperidone in bulk and pharmaceutical dosage form.

Figure 2: UV spectra of Iloperidone (10 μg/mL in 0.1 N HCL)

Procedure for calibration curve:

Aliquots of working standard solution were further diluted with 0.1N HCL into 10 ml volumetric flasks to obtain concentrations of 2, 4, 8, 10, 12, 16 and 20μg/mL. Finally, the absorbance of these solutions were measured at l_maxas recorded in (Table 1), in each case against 0.1N HCL as blank as shown in the overlay spectrum (Figure 3). A calibration graph of the absorbance versus the concentration of the Iloperidone was plotted (Figure 4).

Figure 3: Overlay Spectra of Iloperidone (2-20 μg/mL)

Figure 4: Standard plot of Iloperidone

Procedure for analysis of marketed formulations:

For analysis of commercial formulations, twenty tablets containing Iloperidone were taken and powdered. Tablet powder equivalent to 10 mg of Iloperidone was transferred to 100 mL volumetric flask and dissolved in 0.1N HCL and then the solution was heated gently to dissolve and filtered through Whatman filter paper No. 41. It was further diluted in a 10 ml volumetric flask to obtain the required concentration of 10μg/mL. The absorbance of the above solution was measured against 0.1N HCL as a blank at 229.5 nm.

RESULTS AND DISCUSSION:

The proposed method for determination of Iloperidone showed absorbance maxima at 229.5 nm and molar absorptivity of 2.03 x 10⁴ L/mol.cm. The developed method was validated according to International Conference on Harmonization guidelines for validation of analytical procedures. Linear regression equation of absorbance verses concentration, y = 0.0499x - 0.0111 with a correlation coefficient (r) of 0.9994. The optical characteristics such as Beer’s law limit, Sandell’s sensitivity, inter and intraday precision, limit of detection, limit of quantitation were calculated and are summarized in Table 1. The result of analysis of marketed formulation has been shown in Table 2.

To ensure the reproducibility and accuracy of the method, recovery studies were carried out at three different concentration levels i.e. 80 %, 100 %, and 120 % by adding a known amount of pure drug to the pre analyzed sample of tablet powder and the contents were reanalyzed for the drug content using the proposed method. From the amount of drug found, percentage recovery was calculated and found to be within the range. The results of recovery studies are given in Table 3.

Table-1: Optical characteristics of Iloperidone

Parameters Results

l_max(nm) 229.5

Beer’s law limit (mg/ml) 2-20

Molar absorptivity (L mole^-1 cm^-1) 2.03x10⁴

Sandell’s sensitivity 0.020

(mg cm^-2 / 0.001 absorbance unit)

Regression equation (Y = a + bC) Y = 0.0499x - 0.0111

Slope (b) 0.0499

Intercept (a) -0.0111

Correlation coefficient (r) 0.9994

Intraday precision (%RSD) * 0.58

Interday precision (%RSD) * 1.44

Limit of detection (mg/ml) 0.106

Limit of quantitation (mg/ml) 0.321

*Average of six determinations

Table-2: Analysis of Iloperidone tablets

Brand	Labeled amount mg/tablet	Amount found mg/tablet	% Label claim+ SD*
ILOSURE	6	5.999	99.9+ 0.7

*Average of six determinations

Table-3: Recovery studies of Iloperidone tablets

Brand	% Spike Level added, mg	Amount of drug found, mg	Amount of drug + RSD*	Percentage Recovery
ILOSURE	80	8	7.93	99.1+ 0.40
	100	10	9.99	99.9+ 0.44
	120	12	12.10	100.9+ 0.38

*Average of six determinations

CONCLUSION:

In this study a simple, rapid, sensitive, accurate and precise UV spectrophotometric method for the determination of Iloperidone in bulk and pharmaceutical dosage form has been developed and validated. The spectrophotometric method applied has the advantage of overcome the interference caused by the excipients and the degradation products present, if any, in the formulation. The proposed method can be used for the routine quality control analysis of Iloperidone in bulk as well as in marketed tablet dosage forms.

REFERENCES:

1. URL: http://en.wikipedia.org/wiki/Iloperidone.

2. Mandpe L P. Stress degradation studies on Iloperidone and development of a stability indicating HPLC method for bulk drug and pharmaceutical dosage form. Pelagia Research Library, Der Chemica Sinica. 2(2): 2011: 230-239.

3 Manjula Devi AS. Validation of UV Spectrophotometric and HPLC Methods for Quantitative determination of Iloperidone in Pharmaceutical Dosage Form, International Journal of Pharm.Tech Research CODEN (USA):IJPRIF. 4(2):2012:576-581.

4 Usmangani Chhalotiya K .et al. Liquid chromatographic method for the quantification of antipsychotic agent Iloperidone in pharmaceutical formulation. ISRN Analytical Chemistry, 2: 2012, 55-59.

5 Sekhar Reddy BRC. A novel RP-HPLC method for the quantification of Iloperidone in formulations. Int. J.A.PS. BMS. 1(4): 2012:354-363.

6 Leenata Mandpe P. Stress degradation studies on Iloperidone and development of a stability indicating HPLC method for bulk drug and pharmaceutical dosage. Pelagia Research Library. 2(2): 2011: 230-239.

7 Naresh Chandra Reddy M. et al. Estimation of 6-fluoro-3-(piperidin-4-yl) benzo [d] isoxazole hydrochloride and 1- (4-(3-chloropropoxy)-3-methoxyphenyl) ethanone of Iloperidone in bulk and dosage form by RP-HPLC. International Journal of Pharmacy and Biological Sciences. 2(2): 2012: 208-217.

8 Mutlib AE. et al. Pico gram determination of Iloperidone in human plasma by solid - phase extraction and by high-performance liquid chromatography selected - ion monitoring electro-spray mass spectrometry. J Chromatography Biomed Appl. 669(2): 1995: 237-246.

9 Venkata Mahesh R. et al. Development and validation of derivative UV - spectrophotometric methods for quantative estimation of Iloperidone in bulk and pharmaceutical dosage form. American Journal Pharmtech Research. 1(4): 2011: 311-316.

Received on 12.02.2014 Modified on 28.03.2014

Asian J. Research Chem. 7(4): April 2014; Page 390-392