Development and Validation of Spectrophotometric Method of Analysis for Fexofenadine HCl

PV Polawar, UD Shivhare*, KP Bhusari and VB Mathur

Sharad Pawar College of Pharmacy, Wanadongri, Hingna Road, Nagpur 441 110

*Corresponding Author E-mail: udshivhare@gmail.com

ABSTRACT:

Fexofenadine is a new non sedating oral antinistaminic which is clinically effective in the treatment of allergic rhinitis and is not yet official in any pharmacopoeia. Literature survey has been revealed that there is no any visible spectrophotometric method has been reported for estimation of fexofenadine HCL in bulk form and in pharmaceutical formulation. Hence an attempt has been made to develop and validate a simple, economic, rapid and accurate method.

In present investigation three simple and sensitive extractive spectrophotometric methods have been developed and validated for the determination of fexofenadine HCL in tablet dosage form. The developed methods involve formation of extractable ion pair complex of drug with bromophenol blue, bromocresol purple and bromocresol green dyes in acidic medium. Chloroform is used as extracting solvent for bromophenol blue and 1% v/v amyl alcohol in chloroform is used for Bromocresol purple and bromocresol green. Extractable complexes shows maximum absorption at 416 nm, 412 nm and 419 nm, the drug in the worked experimental shows linearity range for bromophenol blue, bromocresol purple and bromocresol green in concentration ranges of 0-7 mg/ml respectively. The coloured chormophores were found to be stable for 40 min. 60 min and 30 min respectively. The effect of pH and dye concentration was also studied.

The results of analysis for all the three methods have been validated statistically and by recovery studies. The proposed methods were simple, sensitive and economical for the quantitative determination of Fexofenadine HCL and were successfully employed for the estimation of bulk drug and in formulation.

KEY WORDS: Fexofenadine, chormophores, colorimetry.

INTRODUCTION:

Fexofenadine HCL (FH),chemically designated as (±)-4-[1-hydroxy-4-(4- hydroxydiphenylmethyl)-1-piperidinyl]-butyl]-µ,µ-dimethyl benzeneacetic acid hydrochloride¹ is a histamine H₁ receptor antagonist used in patients with allergic rhinitis.. FH can be estimated by HPLC methods^2,3but no spectrophotometric method was reported in literature till date. Hence an attempt has been made to develop and validate a simple, economic rapid and accurate method. The three methods described here are based upon colorimetry.

MATERIALS AND METHODS:

Materials – Only A R grade reagents and solvents were used. The pure drug Fexofenadine HCL was obtained as a gift sample from Sun pharmaceuticals Ltd., Silvassa (Guj)

Instrument:- Shimadzu UV-Visible double beam Spectrophotometer (model 1601) was used for spectral studies. Shimadzu - UV– 150-20 was used in validation parameter

Standard solution:-

Stock Standard Solution: Accurately weighed quantity of FH (100 mg) was dissolved in methanol (10.0 mL) in a volumetric flask (100.0 mL) and volume made upto the mark with distilled water.

Standard Solution-A: A 1.0 ml of stock standard solution was diluted to 100.0 ml with distilled water (concentration 10 mcg/ml)

Sample Solution– Twenty tablets were weighed and finely powdered. A quantity of tablet powder equivalent to 100 mg of FH taken in volumetric flask (100 ml) was shaken with methanol (10.0 ml) for 10 min and the volume was made upto the mark with distilled water. The solution was then filtered through whatman filter paper and the aliquot portion of the filtrate was diluted to 100.0 ml with distilled water to get sample solution A-1.

Table No. 1 : Optimum Assay Conditions

Parameters	Dyes
Parameters	Bromophenol blue	Bromocresol purple	Bromocresol green
Wavelength Maximum	416 nm	412 nm	419 nm
pH of aqueous phase	3.0	2.0	2.0
Extracting solvent	CHCl₃	1% v/v amyl alcohol in CHCl₃	1% v/v amyl alcohol in CHCl₃
Dye concentration	1 mg/ml	1 mg/ml	1.25 mg/ml
Colour stability	40 min	60 min	30 min
Concentration range	0-7 mcg/ml	0-10 mcg/ml	0-15 mcg/ml

Table No. 2 : Summary of results of acid-dye colorimetric methods.

Sample code	Bromophenol blue		Bromocresol purple		Bromocresol green
Sample code	% Label claim*	% Recovery*	% Label claim*	% Recovery*	% Label claim*	% Recovery*
Allegra (Tablet A)	99.70	99.51	99.71	100.31	98.01	98.49
Curefix (Tablet B)	98.95	100.07	98.76	99.41	98.43	100.22
Fexidine(Tablet C)	99.07	99.50	99.30	99.51	99.87	99.37

PROCEDURE: (For estimation of Fexofenadine hydrochloride in tablet)

Using Bromophenol Blue (BPB)

Accurately measured portion (5.0 ml) of standard solution – A and sample solution – A-1 were taken in different separating funnels. To each of the separating funnel, dye solution (5.0 ml), buffer solution (5.0 ml, pH 3) and chloroform (10.0 ml) was added. The separating funnels were shaken for 2 min. The layers were allowed to separate. The separated layers were collected in dry test tubes containing anhydrous sodium sulphate. The absorbance of each organic layer was measured in 1.0 cm cell at 416 nm against blank.

Using Bromocresol Green (BCG)

Similar procedure described above using BCG dye solution (5.0 ml) and buffer solution (5.0 ml, pH 2) in place of dye and buffer was used. The absorbance of organic layer was measured at 419 nm against blank.

On the basis of various parameters studied, the following assay conditions were fixed for the assay of FH by acid dye method using bromophenol blue, bronocresol purple and bromocresol green dyes.

Using Bromocresol Purple (BCP)

Similar procedure described above was followed using BCP dye solution (5.0 ml) and buffer solution (5.0 ml, pH 2) in place of dye and buffer was used. The absorbance of organic layer was measured at 412 nm against blank.

The accuracy and specificity of the proposed method was revealed by the results of the validation as,

1. The five different test concentrations were studied for accuracy and precision of the method.

2. Specificity was studied by measuring the degree of interference at room temperature at 50⁰C after addition of 0.1 N HCL, at 50⁰C after addition of 3% H₂O₂ and at 50⁰C by heating and all samples kept for 24 hrs.

3. Ruggedness studies have carried out under three conditions i.e. instruments, dyes and analysis.

RESULTS AND DISCUSSION:

In this study, Fexofenadine HCL forms extractable ion pair complex with BPB, BCP and BCG dyes, which is soluble in CHCl₃, 1% v/v amyl alcohol in CHCl₃ respectively and measured quantitatively at 416 nm, 412 nm and 419 nm respectively. The optimum conditions were establish by varying one parameter at a time and keeping the other parameters fixed and observing the effect produced on the absorbance of chromogen. For accuracy of the method, the five different test concentration have yielded the results within range. For precision study, the five samples from the same batch have shown the results within acceptance limit i.e. % RSD below 2.0.For linearity studies, the lines are passing through the origin. Ruggedness studies have carried out under three different conditions and results indicates that the method was reproducible and independent of environmental variables.

CONCLUSION:

It is concluded from the results that the proposed acid-dye colorimetric methods was accurate and precise. However, proposed methods which well validated seem to be quite sensitive and can be successfully applied for the routine analysis of fexofenadine HCL in its tablet formulation. The proposed method was made most accurate by the result of recovery study shown in Table No.2

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Received on 20.12.2008 Modified on 30.12.2008

Research J. Pharm. and Tech. 1(4): Oct.-Dec. 2008;Page 539-540