Estimation of Aripiprazole in Bulk Drug and Formulation by UV-Derivative Spectroscopy

 

Sarma Shreya Balaram, Akula Ramesh and Jagadish P.C.^*

Department of Pharmaceutical Quality Assurance, Manipal College of Pharmaceutical Sciences,

Manipal University, Manipal, 576104, Karnataka, India.

 

ABSTRACT:

Aripiprazole is an atypical neuroleptic drug used to manage conditions like schizophrenia and bipolar disorder. The aim of current work is to compare UV spectrophotometric and derivative techniques of aripiprazole to establish simple, sensitive method. In different spectrophotometric orders of aripiprazole, zero order has shown maximum absorbance at 217nm. Experimental wavelengths in other derivative orders were selected considering maximum absorbance. Wavelength difference and smoothing factor values were optimized to give improved spectral resolution and sensitivity. The method was linear and obeyed Beer’s law in the range of 1.0-6.0 µg/mL. Linearity, limit of detection (LOD), limit of quantitation (LOQ) and accuracy were evaluated for each order as per ICH Guidelines. First order has shown highest correlation coefficient with lower values of LOD and LOQ whereas other derivative orders have shown higher values. So, first order derivative spectroscopy was identified as the best for the estimation of aripiprazole in bulk drug and formulation.

 

 

INTRODUCTION:

Aripiprazole, chemically is 7-{4-[4-(2, 3-dichlorophenyl) piperazin-1-yl] butoxy} -3,4-dihydroquinolin-2-one [Figure 1] with a molecular formula C₂₃H₂₇Cl₂N₃O₂ and molecular weight 448.385. ^[1]

 

Figure 1: Aripiprazole chemical structure

 

Aripiprazole is a partial dopamine agonist, shows its antipsychotic activity by a combination of partial agonist activity at D2 and 5-HT1A receptors and antagonist activity at 5-HT2A receptors. Hence, it can be useful to relieve both positive symptoms and negative symptoms of schizophrenia. ^{[1, 2]} 

 

Derivative spectroscopy refers to the process of modification of a normal spectrum to its first, second or higher derivative spectrum. It can be used to clarify absorption bands in more complex UV spectra by using first or higher derivatives of absorbance with respect to wavelength. Gaussian band which represents an ideal absorption band is used as reference to understand the transformations occur in the derivative spectra. The derivative spectrum is measured either by the zero-crossing technique or the “peak-to peak” technique, or the “baseline–to peak” technique. ^{[3, 4, 5, 6]} Following are the advantages of derivative spectrophotometry over classical spectrophotometry: ^[7]

1) Useful in quantification analysis either for characterizing materials or for identification.

2)    Resolution between bands can be achieved with increase in order due to decrease in derivative centroid bandwidth.

3)    It eliminates baseline shifts and improves the accuracy of the method.

4)    Quantification of a narrowband component in presence of broadband component can be achieved by reducing errors caused by scattering.

5)    Identification and detection of trace levels of component in presence of strongly absorbing matrix.

 

Literature review reveals several analytical and bioanalytical methods for the estimation of aripiprazole including LC-MS methods^[8,9], HPLC methods^[10-12] and UV-Visible spectrophotometry methods ^[13,14]. Nevertheless no derivative spectroscopic methods were found in the literature for the determination of aripiprazole in tablets. The objective of current work is to compare the zero, first, second and third order spectroscopic techniques and to find out the most appropriate, sensitive and suitable spectrophotometric order which can be routinely used in quality control analysis for the estimation of aripiprazole in tablets.

 

MATERIALS AND METHODS:

Instruments:

UV-Visible spectrophotometer (UV-1800, Shimadzu Co, Japan) with a spectral bandwidth 0.1nm and wavelength accuracy ±0.5nm, a pair of 3cm quartz cells, Eppendorf micropipette of 100-1000μL and Sartorius electronic balance were used.

 

Chemicals and Reagents:

Aripiprazole standard (99.99%) was procured from Lupin pharmaceuticals, Pune as a gift sample. Acetonitrile was purchased from Merck. Aripiprazole tablets (Arpizol 30mg) were purchased from a local pharmacy.

 

Method development:

Selection of wavelengths:

Absorbance of working standards was determined at 217 nm for zero order, 209nm for first order, 199nm for second order and 223nm for third order respectively when scanned within the range of 190-400nm.

 

Figure 2: Aripiprazole spectrum

Preparation of stock solution:

Aripiprazole stock solution (1000µg/mL) was prepared by adding 25mg of aripiprazole to a 25mL volumetric flask containing 10mL of acetonitrile and sonicated for 2 minutes. Then the volume was made up to 25mL using same solvent. This stock solution was further diluted with the acetonitrile to obtain a standard solution of 100µg/mL. Acetonitrile was used as the solvent which offers minimal background interference.

 

Preparation of tablet solution:

Ten tablets of Arpizol (30mg of aripiprazole tablets) were weighed, powdered and average weight equivalent to 10 mg was accurately weighed and introduced into a 10mL volumetric flask, sonicated for 2 minutes with 5mL of acetonitrile and volume was made up to the mark with same. Then it was filtered through whattman filter paper no.41. From this, 10µg/mL solution was prepared.

 

Derivative spectroscopic analysis:

In derivative spectroscopy, wavelength range is affected by wavelength difference (Δλ) and n (smoothing factor) values. Noise is inversely proportional to wavelength difference and optimal wavelength range makes the peaks sharper and increases S/N ratio. Controlling the degree of smoothing improves sensitivity of the method. ^[15] A series of n values (n = 1-9) were tested for aripiprazole standard solutions of concentrations 1.0 – 6.0µg/mL and optimum values include wavelength range 190-300 nm, n = 9, Δλ = 2 nm were selected in the first, second and third-order derivative spectra.

 

RESULTS:

Method validation:

As per ICH guidelines specificity, accuracy, precision, linearity, LOD, LOQ and robustness were performed. ^[16]

 

Specificity:

The standard (10µg/mL) and formulation (10µg/mL) solutions of aripiprazole, when scanned in the range of 190-400nm showed similar absorption spectra. Hence, it was concluded that excipients did not interfere with the quantitation of aripiprazole [Figure 3].

 

Figure 3: specificity

Precision:

Intra-day and Inter-day precision were performed by analyzing three different concentrations of aripiprazole twice in a day and on two different days.

 

Table 1: Intra-Day precision

Concentration (µg/mL)	Absorbance	%RSD
3	0.4458	0.5053%
	0.4462
	0.4499
4	0.5594	0.4773%
	0.5640
	0.5641
5	0.7010	0.3135%
	0.7034
	0.7054

 

Table 2: Inter-Day precision

Concentration (µg/mL)	Absorbance		%RSD
	Day 1	Day 2
3	0.4458	0.4379	1.1507%
	0.4462	0.4382
	0.4499	0.4391
4	0.5545	0.5594	0.9483%
	0.5564	0.5640
	0.5509	0.5641
5	0.6928	0.7010	0.8507%
	0.6930	0.7034
	0.6924	0.7054

 

Accuracy:

Accuracy (recovery) studies were performed by standard addition method at three concentration levels 80%, 100%, and 120% by spiking appropriate amount of drug to the tablet solution of 100% concentration [Table 3].

 

Linearity:

The proposed method of analysis for aripiprazole was found to be linear in the range of 1-6μg/mL. The correlation coefficient of calibration curve obtained was with in the acceptable limits [Table 4] [Fig. 4a, 4b, 5a, 5b, 6a, 6b, 7a, and 7b].

 

Limit of detection (LOD) & Limit of quantitation (LOQ):

LOD and LOQ values of aripiprazole in different derivative orders were calculated from their respective regression equations [Table 4].

 

Table 3: Accuracy results in different orders

Order	Recovery level	% Recovery	%Recovery (Mean)	% RSD
Zero	80	101.24%	100.68	0.42%
	100	100.21%
	120	100.61%
First	80	99.24%	100.01	0.85%
	100	99.61%
	120	101.2%
Second	80	87.11%	88.49	3.81%
	100	85.23%
	120	93.13%
Third	80	102.10%	101.6	0.92%
	100	100.29%
	120	102.41%

 

Figure 4(a): zero order derivative spectrum

 

Figure 4(b): zero order linearity graph

Table 4: Linearity results in different orders

Order	Range (µg/mL)	Wavelength (nm)	Regression equation	Slope	Intercept	r2	LOD (µg/mL)	LOQ (µg/mL)
Zero	1 – 6	217	y=0.1343x+0.0148	0.1343	0.0148	0.9999	0.1124	0.3408
First	1 – 6	209	y=0.0499x+0.0015	0.0499	0.0015	0.9997	0.0116	0.0350
Second	1 – 6	229	y=0.0147x+0.00007	0.0147	0.00007	0.9997	0.0470	0.1426
Third	1 – 6	199	y= 0.0036x+0.0001	0.0036	0.0001	0.9982	0.1522	0.4612

 

Figure 5(a): first order derivative spectrum

 

Figure 5(b): first order linearity graph

 

Figure 6(a): Second order derivative spectrum

 

Figure 6(b): Second order linearity graph

 

Figure 7(a): Third order derivative spectrum

 

Figure 7(b): Third order linearity graph

Robustness:

The evaluation of robustness was done by deliberate variation of maximum absorbance wavelength.

 

Table 5: Robustness:

Wavelength (nm)	Absorbance	%RSD
216	0.5783	0.3553 %
217	0.5806
218	0.5665

 

DISCUSSION:

Aripiprazole is soluble in solvents like acetonitrile, ethanol and sparingly soluble in methanol. Ethanol and methanol showed higher background interferences at its lambda maximum as compared to acetonitrile. Hence, acetonitrile was selected as the solvent. The calibration curves were constructed at the wavelengths corresponding to maxima at analytical wavelengths 217nm, 209nm, 199nm, 223nm for zero order, first order, second order and third order respectively. Linearity and accuracy parameters for each derivative order was carried out and compared with the zero order. Out of all, first and third order derivatives showed better recoveries while LOD and LOQ values were lower for first [Table 6].

 

Table 6:Comparison of derivative orders

Parameters	Zero order	First order	Second order	Third order
λ max	217	209.20	199.20	223.20
r2	0.99994	0.9997	0.9997	0.9982
Slope	0.13434	0.0499	0.0147	0.0036
Intercept	0.01483	0.0015	0.00007	0.0001
LOD(µg/mL)	0.11240	0.01158	0.0470	0.1522
LOQ(µg/mL)	0.34080	0.0350	0.1426	0.4612
%Recovery	100.68%	98.86%	88.48%	101.6%

 

CONCLUSION:

The first order derivative was more sensitive having lower LOD and LOQ values and found to be more accurate, reproducible, and sensitive when compared to zero order UV spectroscopic method for quantification of aripiprazole. Hence, the first order method can be routinely used in quality control analysis to assess pharmaceutical tablet formulation.

 

REFERENCES:

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Received on 15.05.2014                Modified on 15.06.2014

Accepted on 24.06.2014                © RJPT All right reserved