Validated UV- Spectroscopic estimation of Simvastatin Concentration in Bulk and Dosage form

 

Pramod Nanasaheb Katkade¹, Ravindranath Bhanudas Saudagar²

¹Department of Pharmacy, Pacific University, Udaipur, Rajasthan- 313003

²Department of Quality Assurance Techniques, KCT’s R. G. Sapkal College of Pharmacy, Anjaneri, Nashik

*Corresponding Author E-mail: pramod_katkade@rediffmail.com.

A simple, accurate, precise, and sensitive a highly selective ultra violet spectrophotometric method has been developed for the estimation of drug  in bulk and dosage form. It shows maximum absorbance at 238nm.  The Beer-Lambert’s law was obeyed in the concentration range of 5-35µg/ml. The linear regression analysis data for calibration plots showed good linear relationship and obtain correlation factor for Simvastatin. The percentage recovery was found to be within range. Thus method was successfully applied for routine analysis of Simvastatin in bulk drug and dosage form.

 

 

 

1. INTRODUCTION:

Simvastatin chemically is (1S,3R,7S,8S,8aR)-8-[2-[(2R,4R)-4-hydroxy-6-oxotetrahydro-2H-pyran-2-yl ] ethyl] - 3,7- dimethyl -1, 2, 3, 7, 8, 8a – hexahydronaphthalen -1-yl 2, 2-dimethylbutanoate. Simvastatin is HMG Co-A reductase inhibitor which is useful in management of increased lipid level. It is derived synthetically from fermentation products of Aspergillus terreus. It is a white or almost white, crystalline powder, practically insoluble in water, very soluble in methylene chloride, freely soluble in  alcohol.^1-3

 

2. MATERIALS:

2.1 Instrument: Absorbance was measured, and the Spectra was recorded over the wavelength of 200-400 nm using a double beam UV- Spectrophotometer Jasco V-630.

 

2.2 Materials: Simvastatin  was obtained as a gift sample from Sterling Biotech, Methanol, Distilled water and other reagents were of analytical grade.

 

3. METHOD:

3.1 Preparation of Stock solutions

Standard Simvastatin 10 mg was weighed and dissolved in 5 mL of methanol in a 100 ml volumetric flask. The flask was shaken and volume was made up to the mark with distilled water to prepare a solution containing 100 µg / ml (stock solution A).^5-7

 

3.2 Selection of analytical concentration ranges

From the standard stock solution  A of  Simvastatin, appropriate aliquots were pipetted out into 10  ml volumetric flasks and dilutions were made with distilled water to obtain working standard solutions of concentrations from  2 to 100 μg / ml. Absorbance for these solutions were measured at absorption maxima at 238 nm. For the standard solution analytical concentration range were found to be 5 -35 µg / ml and those values were reported in Table no. 2.^5-7

 

3.3 Calibration curve for the Simvastatin (5 – 35 µg / ml)

Appropriate volume of aliquots from standard Simvastatin stock solution  A were transferred to different volumetric flasks of 10 ml capacity. The volume was adjusted to the mark with distilled water to obtain concentrations of  5, 10, 15, 20, 25, 30 and 35 µg / ml. Absorbance spectra of each solution against distilled water as blank were measured at 238 nm and the graphs of absorbance against concentration were plotted and shown in Figure 1. The regression equation and coefficient of determination was determined.^5-7

 

3.4 Sample preparation for determination of Simvastatin from dosage form

Ten tablets of a brand were weighed and finely powdered. The powder equivalent to 10 mg of Simvastatin was accurately weighed and transferred to volumetric  flask of 100  ml  capacity containing 5 ml of the methanol and sonicated for 5 min. The flask was shaken and volume was made up to the mark with distilled water  to give a solution of 100 µg / ml (stock solution B). The above solution carefully filtered through Whatmann filter paper (No. 41) and used for the estimation of Simvastatin. To examine the absence of either positive or negative interference of excipients used in formulation, recovery studies were carried out.^5-7

 

4. VALIDATION METHOD:

4.1 Accuracy

Accurately weighed formulation sample equivalent to 10 mg of sample were mixed with 10 mg of Simvastatin pure drug. From above equivalent 20 mg mixture 10mg equivalent weight of sample were dissolved in 5 ml of methanol and further volume make up with distilled water. Solutions were analyzed. ⁴

 

4.2 Precision

The parameter was validated by assaying number of aliquots samples of Simvastatin and its validity was estimated using parameters such as Standard deviation and Relative Standard deviation.⁴

4.3 Recovery Studies

Accurately weighed formulation sample equivalent to 10 mg of sample were mixed with 10 mg of Simvastatin pure drug. From above equivalent 20 mg mixture 10mg equivalent weight of sample were dissolved in 5 ml of methanol and further volume make up with distilled water. Different concentrations like 5, 10, 15, 20, 25, 30 and 35 µg / ml were taken and absorbance was recorded.⁴

 

5. RESULT AND DISCUSSION:

5.1 Determination of wavelength and calibration graph

The λmax of  Simvastatin was found to be 238 nm in methanol and distilled water. The absorbance was measured at 238 nm against methanol and distilled water. The calibration curve was prepared by plotting absorbance versus concentration of drug.

 

5.2 Determination of Molar Absorptivity

Absorptivity constant is the ratio of the absorbance of the sample of the product of the thickness of the medium and concentration of the sample. Increase or decrease in absorbance depends upon Increase or decrease in concentration which always remain constant. The absorbance of different concentrations was determined at 238 nm and molar absorptivity calculated using following formula,

a= A/ bc

Where,

a= Absorptivity

A= Absorbance

b= Pathlength

c= Concentration

 

5.3 Effect on Absorbance with Time (Stability)

The stability of sample was checked by taking absorbance at regular interval of time. Absorbance remains stable for 320 min. than the absorbance decreased with time.

 

6. CONCLUSION:

From the results, it can be concluded that the proposed method for the estimation of Simvastatin is simple, convenient, accurate, sensitive and reproducible. It can be successfully used for routine analysis of the Simvastatin in bulk and pharmaceutical dosage forms.

 

Table no. 1: Optical Characteristics of Simvastatin

Parameters	Results
Absorption maximum	238 nm
Beer’s law limit (μg / ml)	5-35 (μg / ml)
Correlation coefficient (r2)	0.9983
Regression equation (y = mx + c)                                Slope (m) Intercept (c)	y =0.0213x + 0.1477 0.0213x 0.1477

Table no. 2: Results of calibration curve at 238 nm for Simvastatin by UV spectroscopy

 

Sr. no	Concentration (µg / ml)	Absorbance (nm)
1	05	0.2468
2	10	0.3567
3	15	0.4762
4	20	0.5876
5	25	0.6674
6 7	30 35	0.7864 0.8886

 

Table no. 3: Accuracy results of Simvastatin at 238 nm

Amount of Sample (µg / ml)	Amount of Drug Added (µg / ml)	Amount recovered (µg / ml)	% Recovery ± SD
10	8	17.68	98.22
20	10	29.70	99.00
30	12	41.30	98.33

 

Figure no.1 Linearity plot or calibration curve for Simvastatin at 238 nm by UV spectroscopy

 

 

Table no. 4: Precision results of Simvastatin at 238 nm

Conc. μg / ml	Inter-day Absorbance**	% RSD	Intra-day Absorbance**	%RSD
5	0.2468 ± 0.2264	0.0164	0.2462 ± 0.1321	0.0166
10	0.3567 ± 0.3153	0.0124	0.3554 ± 0.3145	0.0154
15	0.4762 ± 0.2632	0.0145	0.4699 ± 0.3237	0.0121
20	0.5876 ± 0.2572	0.0133	0.5866 ± 0.2347	0.0088
25 30 35	0.6674 ± 0.2167 0.7864 ± 0.1136 0.8886 ± 0.3256	0.0145 0.0054 0.0067	0.6656 ± 0.2478 0.7855 ± 0.3267 0.8878 ± 0.2489	0.0132 0.0172 0.0056

 

Table no. 5: Ruggedness results of Simvastatin at 238 nm

Analyst	Label Claim   mg	Amount found mg	% Recovery ± SD
Analyst I	10	9.85	98.50 ± 0.45
Analyst II	10	9.91	99.10 ± 0.58

 

7. REFERENCES:

1.     The United States Pharmacopeia USP 28/ NF 23, Asian Edition, The United States Pharmacopoeial Convention, Inc., Rockville, MD. 2005, 3179.

2.     British Pharmacopoeia, Vol. I, Controller of Her Majesty’s Stationary Office, Norwich, 2004, 1563.

3.     The Merck index, Edition 13, pp.868.

4.     International Conference on Harmonization of  Technical Requirements for the Registration of Pharmaceuticals for Human use. 1996.Validation of Analytical procedures: Methodology. ICHQ2B, Geneva, (CPMP/ICH/281/95).

5.     Vogel’s Textbook of Quantitative Chemical Analysis, 5 ^th edition, ELBS Longman, London, 1997, 661-672.

6.     Miller JC, Miller JN. In: Statistics for Analytical Chemistry, 2nd ed, Wiley, New York, 1984: 83–117

7.     Tan L, Yang LL, Zhang X, Yuan YS and Ling SS. Determination of simvastatin in human plasma by highperformance liquid chromatography. 2000;18(3):232-234.

7.

 

 

Received on 06.06.2016         Modified on 20.06.2016

Accepted on 27.06.2016         © AJRC All right reserved