Assay of Tolperisone by Extractive Spectrophotometry

K. Raghavi*, M. Shaiba, V. Jagathi, M. Sindhura and R. Prashanthi

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

*Corresponding Author E-mail: msindhu44@gmail.com

ABSTRACT:

Two simple and sensitive visible spectrophotometric methods have been developed for the estimation of Tolperisone in pure and pharmaceutical dosage forms. Method A is based on co-ordinate complex formation between the drug and cobalt thiocynate (630 nm) and method B is based on charge transfer complex formation between drug and 2,3 di-chloro-5-6-dicyano 1-4,benzoquinone (DDQ 430 nm) .The absorbance are measured against the corresponding reagent blanks. The methods have been statistically evaluated and found to be precise and accurate.

KEYWORDS: Spectrophotometry, Tolperisone.

INTRODUCTION:

Tolperisone which is chemically 2-methyl-1-(4-methylphenyl)-3-(1-piperidyl)-propan-1-one¹ is a centrally acting muscle relaxant which acts by inhibiting voltage-gated sodium and calcium channels². It is used to treat acute muscle spasms in back pain and spasticity in neurological disorders. A number of methods such as HPLC^3,4and visible spectrophotometry⁵ were reported for the estimation of Tolperisone, in its pure form and pharmaceutical formulations. Literature survey⁶ reveals that visible spectrophotometric methods have not been reported for its quantitative determination its pure form and pharmaceutical formulations. In the present investigation, two simple and sensitive visible spectrophotometric methods have been developed for the determination of Tolperisone. The developed methods involve the formation of colored complexes with cobalt thiocynate and DDQ. The colored chromogens showed the absorption maximum at 630 and 430 nm respectively. Beers law is obeyed in the concentration ranges of 5-30 µg/ml and 50-250 µg/ml respectively. The results of analysis for the two methods have been validated statistically and by recovery studies.

MATERIALS AND METHODS:

Preparation of Reagents:

1. Cobalt thiocynate Solution: 7.25g of cobalt nitrate and 3.8g of ammonium thiocynate was dissolved in 100 ml of water.

2. DDQ solution: 0.4% DDQ in 20 ml 1, 4 dioxan was dissolved in 100 ml of acetone.

3. Acid Phthalate Buffer pH 2.2 [I.P.]

4. Standard drug solution: About 100mg of Tolperisone was accurately weighed and dissolved in 100ml water to obtain a stock solution of 1mg/ml. This solution was further diluted with distilled water to get working standard solution of 100g/ml.

ASSAY PROCEDURES:

Method A:

Aliquots of working standard solution of Tolperisone ranging from 1-3 ml were transferred into a series of separating funnels. To this 4 ml of acid phthalate buffer and 5 ml of cobalt thiocynate were added. Volume is made with 15 ml water and finally extracted with 10 ml nitrobenzene. The absorbance of the blue colored chromogen was measured at 630 nm against reagent blank and the amount of Tolperisone present in the sample solution was computed from its calibration curve.

Method B:

Aliquots of working standard solution of Tolperisone ranging from 0.1-0.5 ml were transferred into a series of 10 ml volumetric flasks. To this 1 ml of DDQ was added. Finally the volume was made up to 10ml with acetone. The absorbance of the yellow colored chromogen was measured at 430 nm against reagent blank and the amount of Tolperisone present in the sample solution was computed from its calibration curve.

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
λ_max(nm)	630	430
Beer’s law limit (µg/ml)	5-30	50-250
Sandell’s sensitivity (µg/cm²/0.001 abs. unit)	0.00379	0.03366
Molar absorptivity(litre.mole^-1.cm^-1)	7.433× 10³	8.372× 10³
Regression equation(Y*)
Slope(b)	0.028	0.025
Intercept(a)	0.246	0.002
Correlation Coefficient(r)	0.993	0.994
%Relative standard deviation	0.237	0.348
% Range of error
0.05 Significance level	0.198	0.290
0.01 Significance level	0.293	0.430

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

Table 2: Estimation of Tolperisone in Pharmaceutical Formulations

Formulations (tablets)	Labelled Amount (mg)	*Amount found by proposed method**		% recovery by proposed method**
Formulations (tablets)	Labelled Amount (mg)	Method A	Method B	Method A	Method B
Tablets 1	150	149.3	149.2	99.56	99.68
Tablets 2	150	149.5	149.8	99.42	99.73
Tablets 3	150	148.9	149.7	99.38	99.82

*Average of determinations

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

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

CONCLUSION:

The proposed methods are applicable for the assay of drug Tolperisone 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 Tolperisone in pure form and formulation with reasonable precision and accuracy.

REFERENCES:

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

2. Kocsis P, et al.(2005). J Pharmacol Exp Ther 315 (3): 1237–46.

3. Jung-Woo Bae, et al. Arch Pharm Res 2006, Vol 29, No 4, 339-342.

4. Napaporn Youngvises, et al. Journal of Chromatography.

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

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