INTRODUCTION:

Hypertension is one of the most prevailing ailments in India. Telmisartan is chemically 4'-((1, 4’-Dimethyl-2'-propyl(2,6'-bi-1H-benzimidazol)-1'-yl) methyl) -(1,1'-biphenyl)-2-carboxylic acid. The angiotensin II receptor antagonist (angiotensin receptor blocker, ARB) used in the management of hypertension. It was discovered by Boehringer Ingelheim and launched in 1999 as Micardis. Telmisartan is an oral drug that is used to treat high blood pressure. It may also be used to lower risk for heart attack, stroke, or death of people in the age group of 55years or older and cannot take angiotensin converting enzyme (ACE) inhibitor. High blood pressure is a common condition and when not treated can cause damage to the brain, heart, blood vessels, kidney failure, loss of vision, and other problems. In addition to take medication, making life style changes will also help to control your blood pressure. These changes include eating a diet that is low in fat and salt, maintaining a healthy weight, exercising atleast 30mins per day, not smoking and using alcohols in moderation. Telmisartan is also used sometimes to treat heart failure and diabetic nephropathy.

Fig: 1 Telmisartan

MATERIAL AND METHODS:

Instrument:

Chromatographic separation was performed on UV3092 Labindia – UV/Visible spectrophotometer

Chemicals and Reagents:

Telmisartan were purchased from Yarrow Chem Ltd, Mumbai. Sodium hydroxide of Analytical grade was purchased and Distilled Water was used.

Solubility studies:

100mg of Telmisartan was added to a screw capped different three, 100 ml of volumetric flask containing water, methanol and 0.1M sodium hydroxide respectively. The volumetric flasks were shaken mechanically in a sonicator, then the solubility of each flask is observed. The flask containing water is totally insoluble, flask containing methanol is sparingly soluble and the flask containing sodium hydroxide is totally soluble.

METHOD DEVELOPMENT:

Preparation of Stock solution:

Accurately weighed 100 mg of Telmisartan was transferred in to 100 ml volumetric flask containing 100 ml of 0.1M sodium hydroxide. Then it was kept over a sonicator until the drug dissolved completely in sodium hydroxide.

Assay of Telmisartan:

Marketed formulation Adcom (Intel) was selected for tablet analysis, i.e. containing 10 mg of Telmisartan. Twenty tablets were accurately weighed, average weight determined and ground to fine powder. An accurately weighed quantity of powder equivalent to 50 mg of Telmisartan was transferred into 50 ml volumetric flask containing 40 ml of hydrotropic solution. The flask was sonicated for about 20 min to solublize the drug; volume was adjusted to mark with Na OH and filtered through whatman filter paper no. 41. The Absorbance of sample solutions was analyzed on UV spectrophotometer at 295 nm against distilled water as blank. Drug content of tablet formulation was calculated using the following formula.

A_T

Amount = × C_S× D_F× W

A_S

Where,

A_T = absorbance of test solution

A_S= Absorbance of standard solution

C_S= Concentration of standard solution

D_F= Dilution factor

W = Weight taken

Linearity and Range:

Different concentrations of Telmisartan ranging from 1µg/ml – 6µg/ml were prepared, scanned and the absorbance was measured at 295nm. The results are tabulated in the table 1.

Figure 2: Overlay spectrum of Telmisartan standard showing linearity at 295nm.

Table 1: Absorbance data of different concentrations of Telmisartan

Sl. No	Concentration of Telimasartan	Absorbance
1	1	0.101
2	2	0.191
3	3	0.288
4	4	0.392
5	5	0.495
6	6	0.602

Figure 3: Calibration graph of Telmisartan

Accuracy:
To check the accuracy of the method the prepared from marketed formulation was subjected to analysis by both methods. The results are shown in Table 2. Mean of three values is 99.7%w/w. The estimated percentage purity was found to be close to 100% w/w which proves the accuracy of the method

Table 2: Assay results showing accuracy of the methods

Amount Present Concentration (µg/ml)	Amount found (µg/ml)	% Purity (w/w)
20	19.84	99.22
30	29.88	99.61
40	40.20	100.5

Statistical Parameter:

The results obtained by repeating the estimation procedure four times were observed to have good statistical parameters as given in Table 3.

Table 3: Statistical Parameter for the Telmisartan

TIME	Amount found (µg/ml)	S. D	% RSD
MORNING	29.82	0.0010	0.6991
EVENING	29.82	0.0011	0.7614
MORNING	29.69	0.0001	0.7184
EVENING	30.02	0.0003	0.7847

Limit of Detection and Limit of Quantification:

The limit of detection and limit of quantification for Telmisartan were found to be 0.17μg/mL and 0.34μg/mL respectively.

Table 4: Optical Characteristics of Telmisartan

Parameters	Telmisartan
Limit of Detection	0.0997
Limit of Quantifiaction	0.3023

Recovery:

The marketed formulation was subjected to further analysis to check the reproducibility of the method. The results are shown in Table 5. The percentage recovery is from 97-103% the method is reproducible.

Table 5: Result of Recovery studies

S. No	Amount present (µg/ml)	Amount Added (µg/ml)	Amount recovered (µg/ml)	% Recovery
1	10	0	9.74	97.37
2	10	10	19.48	97.41
3	10	20	29.43	98.09
4	10	30	39.80	99.49
5	10	40	49.37	98.73

DISCUSSION:

For the estimation of Telmisartan from bulk samples and their tablet dosage forms was determined by simultaneous equation method by using UV Spectrophotometer. The regression equation of the linearity curve between concentrations of Telmisartan over its absorbances were found to be y=0.098x0.1008 with a correlation coefficient (r2) of 0.998 for Telmisartan.

CONCLUSION:

As there were several methods reported for the determination of Telmisartan but there is no simple determination, with the easily available solvents so the recent work is useful for the determination of Telmisartan. It is a unique method gives higher and speedy throughput analysis. By the study of validation parameters, it is confirmed that the results obtained from this analytical method are reliable, within the acceptance criteria and the proposed method is immensely robust as per the ICH guideline.

REFERENCES

1. Ajit Pandey, H. Sawarkar, Mukesh Singh, Dr. P Kashyap, Priyanka Ghosh. UV- Visible Spectrophotometric Method for estimation of Telmisartan in Bulk and Tablet Dosage Form. International Journal of Chem Tech Research.2011;3(2): 657-660.

2. Dharmendra K. Damor, Rajashree C. Mashru. Method development and validation of simultaneous estimaton of cilostazol and Telmisartan. International Bulletin of Drug Research. 2015:5(8): 12-22.

3. K. Sonia, Dr. M. Nappinnai, Dr. P. Panneerselvam. Stability indicating Method Development and Validation of Telmisartan and Ramipril by UV Spectrophotometry. Research J. Pharm. and Tech.2018: 11(7): 3087-3090.

4. K. P. Hirpara, Dave V. M., Dr. S. D. Faldu, Dr. B. D. Patel. UV-Spectrophotometric Determination for Simultaneous Estimation of Amlodipine Besylate and Telmisartan in Combination. Journal of Pharmaceutical Science and Bioscientific Research.2012:2(3):133-137.

5. Mayur Modi, Rikin Shah and R.C. Mashru. Development and Validation Of Spectrophotometric Methods For Simultaneous Estimation Of Metoprolol Succinate And Telmisartan In Combined Pharmaceutical Formulation. International Journal Of Pharmaceutical Science and Research. 2012:3(5): 1348-1354.

6. Riddhi Patel, Dilip G. Maheshwari. UV Spectrophtometric Methods For Simultaneous Estimation Of Telmisartan And Cilostazol In Synthetic Mixture. Pharma Science Monitor. 2015: 6(1):276-291.

7. Sonia K, Manikandan K, Hamunyare Ndwabe, Peddamadi Bhavya Sree, Lakshmi KS. Method Development and Validation of simultaneous estimation for Amlodipine besylate and Olmesartan medoxomil by HPTLC method. International Journal of Research in Pharmaceutical Sciences.2018: 9(1): 201-205.

Received on 10.01.2019 Modified on 10.02.2019

Research J. Pharm. and Tech. 2019; 12(5):2413-2415.

DOI: 10.5958/0974-360X.2019.00404.9