Estimation of Diltiazem Hydrochloride from Tablet Formulation Using Spectrophotometric Methods

Nagasuri Ravindra¹, Singhvi Indrajeet^2* and Pillai Sujit²

¹Goenka College of Pharmacy, Lachhmangarh, Dist: Sikar. 332 313. Rajasthan, India.

²Pacific College of Pharmacy, Pratap Nagar Extension, Airport Road, Udaipur. 313 001. Rajasthan, India

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

ABSTRACT

Three simple and sensitive visible spectrophotometric methods have been developed for the quantitative estimation of diltiazem hydrochloride (DITZ) from tablet dosage form. The developed methods are based on formation chloroform extractable colored complex of drug with metanil yellow (MY, method A), tropaeolin 000 (TRP, method B) and alizarin red (AR, method C). The colored complex formed in method A, B, and C showed absorbance maxima at 405.5, 484.5 and 426.0 nm and linearity was observed in the concentration range of 3-24 µg/ml, 3-24 µg/ml and 10-80 µg/ml of DITZ respectively. The results obtained were statistically validated and were found to be reproducible.

KEYWORDS: Diltiazem hydrochloride, Tablets, Spectrophotometric method.

INTRODUCTION:

Diltiazem hydrochloride¹ 1, 5-Benzothiazepin -4 (5H) -one,3-(acetyloxy)-5 [2-(dimethyl amino) ethyl]-2,-3- dihydro-2(4-methoxyphenyl)- mono-hydrochloride, (+)-cis.; is an antihypertensive, antianginal and antiarryhthmic drug. Literature survey reveals that three Spectrophotometric^2-4 and two HPLC^5-6 methods have been reported for the estimation of DITZ from pharmaceutical dosage forms. An attempt has been made in the present study to develop three simple visible spectrophotometric methods for analysis of DITZ in tablet dosage forms.

MATERIALS AND METHOD:

A Shimadzu UV/Visible spectrophotometer- 1700 with 1 cm matched quartz cells was used for spectral measurement. All chemicals used were of analytical grade, metanil yellow solution (0.025% w/v) in acid buffer pH 1.6, tropaeolin 000 (0.03% w/v) in acid buffer pH 1.6 and alizarin red (0.1% w/v) in acid buffer pH 1.2 were prepared and extracted several times with chloroform so as to remove chloroform soluble impurities. Buffer solutions were prepared in double distilled water. The tablet samples of DITZ were procured from the local market.

Procedure for calibration curve:

Accurately weighed (100 mg) pure drug sample of DITZ was transferred to 100 ml volumetric flask, dissolved and made upto mark with chloroform. This stock solution was further diluted with chloroform to get working standard solutions of 30 mg/ml for methods A and B and 100 mg/ml for method C.

Several dilutions of DITZ in a series of 10 ml volumetric flask were prepared with chloroform in concentration range of 3-24 mg/ml for method A and B and 10-80 mg/ml method C of DITZ. To 10 ml of each dilution taken in a separating funnel, 10 ml metanil yellow (method A), tropaeolin 000 (method B) and alizarin red (method C) reagent was added. Reaction mixture was shaken gently for 5 minutes and allowed to stand so as to separate the aqueous and chloroform layer. Colored chloroform layer was separated out and absorbance was measured at 405.5 nm (method A), 484.5 nm (method B) and 426.0 nm (method C) against a reagent blank. A respective calibration curve was plotted from the absorbance values so obtained against concentration.

Procedure for analysis of tablet formulation:

For analysis of formulations, twenty tablets of DITZ were accurately weighed and average weight per tablet was determined. The tablets were powdered and powder equivalent to 50 mg of DITZ was accurately weighed and extracted four times with 20 ml portions of chloroform, the combined chloroform extract was filtered through whatmann filter paper No.41 into 100 ml volumetric flask. The residue was washed with chloroform and the washings were added to the filtrate and the final volume of filtrate was made up to the mark with chloroform. From the above filtrate 10 ml was further diluted to 100 ml in a volumetric flask with chloroform.

For method A and B 2 ml of filtrate was further diluted to 10 ml with chloroform in a volumetric flask. This final dilution was treated as per respective procedure for calibration curve and absorbance was measured at respective wavelength maxima and the amount of drug

Table-1: Optical characteristics, statistical parameters and precision of the proposed methods A, B and C

Parameter	Method-A	Method-B	Method-C
λ_max (nm)	405.5	484.5	426.0
Beer’s law limits (μg/ml)	3-24	3-24	10-80
Molar absorptivity (Lmole^-1cm^-1)	0.2024x10⁶	0.1891x10⁶	0.5660x10⁵
Sandell’s sensitivity (μg cm^-2/0.001 absorbance unit) Regression equation (Y=a+bC)	0.0022	0.0024	0.0080
Slope (b)	0.0446	0.0423	0.0125
Intercept (a)	0.0042	-0.0038	-0.0005
Correlation co efficient (r)	0.9998	0.9999	0.9999
Relative standard deviation (%)*	0.6372	0.2645	0.3050
% Range of error (confidence limits)*
0.05 level	0.5328	0.2212	0.2551
0.01 level	0.7883	0.3272	0.3774

Y=a+bC, where C is concentration in μg/ml and Y is absorbance unit. * Five replicate samples

Table-2: Assay and recovery studies of diltiazem hydrochloride in tablet dosage forms

Sample	Labeled amount (mg/tab)	% Label claim estimated (mg/tab)				% Recovery**
		Proposed method			Reference^* method	A	B	C
		A	B	C
1	60	99.48	99.86	99.78	99.30	99.62	100.09	99.17
2	60	99.73	99.76	99.90	99.43	99.99	100.03	99.59
3	60	60.01	99.61	99.86	98.81	100.53	100.56	100.24

* Reference UV Method developed in our lab ** Average of three determination

present in sample was calculated from respective calibration curve. Result of analysis is reported in table 2. For method C 6 ml of filtrate was further diluted to 10 ml with chloroform in a volumetric flask. This final dilution was treated as per the procedure for calibration curve and absorbance was measured at wavelength maxima and the amount of drug present in sample was calculated from the calibration curve. Result of analysis is reported in table 2.

All the three developed methods were repeated five times on three different tablet formulations.

Recovery studies:

Recovery studies were carried out for all three developed methods by addition of know quantity of pure drug sample to pre analyzed tablet sample solution at three different concentration level. The result of recovery studies is reported in table 2.

RESULT AND DISCUSSION:

The proposed spectrophotometric methods for determination of DITZ from tablet formulation are based on formation of chloroform extractable colored complex of drug with metanil yellow, tropaeolin 000 and alizarin red dye. The pH required for the individual method was optimized. The result of analysis for all three developed method were close to 100% and the statistical parameter and optical characteristic were found satisfactory results of which are reported in table 1. recovery studies were found satisfactory which shows that there is no interference of excipient.

The developed methods were found to be simple, rapid, accurate and can be used for routine analysis of drug from tablet formulation.

REFERENCES:

1. Budvari, S., Eds., In; The Merck Index, 13th Edn., Merck and Co., Inc., White house Station, NJ, 2001, 563 .

2. Ayad MM, Abdalla S and Hosny MM. New colorimetric methods for the determination of trazodone HCl, famotidine, and diltiazem HCl in their pharmaceutical dosage forms. Ana and Bioana Chem. 2003; 376(5): 710-714.

3. Agrawal YK, Shivramachandra K and Rao BE. Spectrophotometric methods for the determination of dilitiazem in pharmaceutical preparations. Ind Jr.of Pharm. Sci. 1992; 54 (6): 218-221.

4. Nafisur R and Hejazazmi SN. Extractive spectrophotometric methods for determination of diltiazem HCl in pharmaceutical formulations using bromothymol blue, bromophenol blue and bromocresol green. Journal of Pharm and Biomed Analysis 2000; 24 (1): 33-41.

5. Sultana N, Arayne MS and Shafi N. A validated method for the analysis of diltiazem in raw materials and pharmaceutical formulations by RP-HPLC. Pak J Pharm Sci. 2007; 20(4): 284- 290.

6. Johnson KE and Pieper JA. An HPLC method for the determination of diltiazem and three of its metabolites in serum. Journal of Liquid Chromatography. 1990; 13 (5) 951-960.

Received on 06.04.2009 Modified on 03.06.2009

Research J. Pharm. and Tech.2 (4): Oct.-Dec. 2009; Page 730-731

Parameter

2. Ayad MM, Abdalla S and Hosny MM. New colorimetric methods for the determination of trazodone HCl, famotidine, and diltiazem HCl in their pharmaceutical dosage forms. Ana and Bioana Chem. 2003; 376(5): 710-714.