New Visible Spectrophotometric Methods for Determination of Nepafenac

 

B. Anupama*, D. Madhavi, S. Amareswari and CH. Hari Prasad

K.V. S. R. Siddhartha College of Pharmaceutical Sciences, Vijayawada-520010, AP, India.

*Corresponding Author E-mail: madhavi30_d@yahoo.com

ABSTRACT:

Two simple and sensitive visible spectrophotometric methods have been developed for the estimation of Nepafenac in pure and pharmaceutical dosage forms. These methods are based on the oxidative coupling reaction between  MBTH(3-Methyl-2-bezothiazolinone hydrazone) and Nepafenac resulting in the formation of  pink colored chromogen ( λ_max 540 nm) and the complex formation between Potassium permanganate and Nepafenac resulting in the formation of  blood red colored chromogen (λ_max 425 nm). The absorbance is measured against the corresponding reagent blanks. These methods have been statistically evaluated and found to be precise and accurate.

 

 

 

INTRODUCTION:

Nepafenac which is chemically 2-Amino-3-benzoylbenzene acetamide. This novel pro-drug rapidly penetrates ocular tissues and is converted intraocularly from nepafenac to amfenac, a potent NSAID¹. A number of methods such as HPLC  was reported for the estimation of Nepafenac in its pure form and pharmaceutical formulations. Literature survey reveals that Visible Spectrophotometric methods have not been reported for its quantitative determination its pure form and pharmaceutical formulations^4-5. In the present investigation, The simple and sensitive visible spectrophotometric methods have been developed for the determination of Nepafenac. The developed method involve the formation of colored  chromogens with MBTH and Potassium permanganate reagent⁶. These colored chromogen showed absorption maximum at 540 nm and 425 nm respectively. Beers law is obeyed in the concentration range of 5-25 µg/ml and 10-50  µg/ml . The results of analysis for the these methods have been validated statistically and by recovery studies.

 

EXPERIMENTAL:

Preparation of Reagents:

1.      MBTH reagent preparation: 0.2 g of MBTH in 100ml distilled water.

2.      Ferric chloride reagent preparation: Dissolve 0.7 g of  Ferric chloride in 100ml of  0.5N HCl.

3.      Standard drug solution (MBTH): Accurately weighed 100mg of Nepafenac in 100ml distilled water from that 1 ml was diluted to 10 ml with water².

4.      Potassium permanganate reagent preparation: 99.54 g of Potassium permanganate in 100 ml distilled water.

5.      Standard drug solution (KMnO4): Accurately weighed 100mg of Nepafenac in 100ml distilled water from that 1 ml was diluted to 10 ml with water³.

 

ASSAY PROCEDURES:

Method A (MBTH):

Aliquots of working standard solution of Nepafenac ranging from 0.5-2.5ml were transferred in to a series of 10ml volumetric flasks. To these 1.5ml of  MBTH regent  wes added and shaken for 2 min. Then 2 ml of Ferric chloride  reagent was added. Wait for 10 min. Finally made upto 10ml with water . The absorbance of the pink colored chromogen was measured at 540 nm against reagent blank and the amount of Nepafenac present in the sample was computed from its calibration curve.

 

Method B (KMnO4):

Aliquots of working standard solution of Nepafenac ranging from 1-5ml were transferred in to a series of 10ml volumetric flasks. To these 1ml of Potassium permanganate reagent was added and wait for 10 min. finally volume was made up to 10ml with water.

 

RESULTS AND DISCUSSION:

The optical characteristics such as Beer’s law limits, Sandell’s sensitivity, molar extinction coefficient, percentage relative standard deviation, percentage range of error (0.05-0.01) were calculated for the method and results are summarized in table 1.

Table-1: Optical characteristics, precision and accuracy of the proposed method

PARAMETERS	Method A	Method B
λmax (nm)	540	425
Beer’s law limit (µg/ml)	5-25	10-50
Sandell’s sensitivity (µg/cm2/0.001 abs. unit)	0.052	0.030
Molar absorptivity(litre.mole-1.cm-1)	0.00048×10 4	0.00084×10 4
Regression equation(Y*)
Slope(b)	0.009	0.019
Intercept(a)	0.177	0.134
Correlation Coefficient(r)	0.9996	0.9996
%Relative standard deviation	0.397	0.348
% Range of error
0.05 Significance level	0.331	0.291
0.01 Significance level	0.488	0.428

Y* = a + bx, where Y is absorbance and x is concentration of Nepafenac in µg/ml.

 

Table 2: Estimation of Nepafenac in Pharmaceutical Formulations

Formulations (Ophthalmic suspension)	Labeled Amount (mg/ml)	Amount found* by proposed method		% recovery** by proposed method
		Method A	Method B	Method A	Method B
Sample-1	5	5.01	4.98	100.1	99.89
Sample -2	5	4.98	4.91	99.89	99.64
Sample- 3	5	4.91	5.01	99.64	100.1

*Average of six determinations; **Recovery of amount added to the pharmaceutical formulation; (Average of three determinations).

 

 

The values obtained for the determination of Nepafenac in pharmaceutical formulation (ophthalmic suspension) by the proposed method is presented in table 2. Studies reveal that the common excipients and other additives usually present in the suspension did not interfere in the proposed methods.

 

CONCLUSION:

The proposed methods are applicable for the assay of drug Nepafenac and have an advantage of wider range under Beer’s law limits. The proposed methods are simple, selective and reproducible and can be used in routine determination of Nepafenac in pure form and formulation with reasonable precision and accuracy.

 

ACKNOWLEDGEMENT:

The authors are grateful to Siddhartha academy of General and technical education, Vijayawada for providing the necessary facilities to carry out the research.

 

REFERENCES:

1.       The Merck Index,13^th edition, pg no-1698, 9600 .

2.       Kocsis P, Farkas S, Fodor L, Bielik N, Thán M, Kolok S, Gere A, Csejtei M, Tarnawa I (2005). J Pharmacol Exp Ther 315 (3): 1237–46.

3.       Jung-Woo Bae, Young-Seo Park, Uy-Dong Shone, Chang-Sun Myung, Byung-Kwon Ryu, Choon-Gon Jang, and Seok-Yong Lee, Arch Pharm Res Vol 29, No 4, 339-342, 2006.

4.       Osama H Abdelmageed, Journal of AQAC International, March-April 2007.

5.       Senthil Kumar K, Lakshmi Siva Subramaniam, Indian Journal of Pharmaceutical Sciences, November-December 2004, 799-882.

6.       Devala Rao G, K.Ratna Kumari, S.Vijaya Kumari, Acta Ciencia Indica, Vol.XXXV,No,281 (2009).

 

 

Received on 06.12.2010        Modified on 29.12.2010

Accepted on 27.01.2011        © AJRC All right reserved