Direct Spectrophotometeric Determination of Metformin Hydrochloride in Pure Form and in Pharmaceutical Formulations

PM Patil, MA Phanse, VL Gaikwad and PD Chaudhari

Modern College of Pharmacy, Nigdi, Pune - 44.

*Corresponding Author E-mail: pallavipatil_2007@yahoo.com

ABSTRACT

A new simple, sensitive spectrophotometric method in ultraviolet region has been developed for the determination of Metformin hydrochloride in bulk and dosage form. Metformin hydrochloride was shown maximum absorbance at 232 nm with apparent molar absorptivity of 1.0781×10 ⁴l/mol.cm. Beer’s law was obeyed in the concentration range of 10 to 50 ug/ml. Results of analysis were validated statistically and by recovery studies. The developed method was found to be sensitive, accurate, precise and reproducible and can be used for the routine quality control analysis of metformin hydrochloride.

KEYWORDS: Metformin hydrochloride, spectrophotometric, Assay, Recovery.

INTRODUCTION:

Metformin hydrochloride is chemically N, N-dimethyllmldicarbonimidic diamide monohydrochloride. It is a local antidiabetic agent with a quicker onset of action¹. Metformin hydrochloride is a drug that has been used to control blood glucose levels with type-2 diabetes patients. The FDA has approver metformin hydrochloride only for treatment of type-2 diabetes. Consequently, some physicians do not have much clinical experience with gluciphage, or are reluctant to use it use it unless the patient has diabetes². Metformin hydrochloride lowers both basal and postprandial elevated blood glucose in patients with NIDDM; when hyperglycemia cannot be satisfactorily managed on diet alone. The highly polar compound escapes metabolism almost entirely, and is eliminated via renal excretion^3-8. Absolute bioavailability of a 500mg immediate-release tablet is about 50 to 60%; the half-life is 2-6h and the maximum plasma concentration is reached after 2.5h, the drug being excreted through the urinary tract unaltered⁹. Metformin appears to work in three ways. First, it decreases the absorption of dietary carbohydrate through the intestines second, it reduce the production of glucose by the liver. Third, and perhaps most importantly, metformin increases the sensitivity of muscle cells to insulin¹⁰. The adverse events most commonly associated with metformin hydrochloride are diarrhea, nausea, and upset stomach. Lactic acidosis is a rare, but serious side effect.

Literature survey revealed that there is no UV- spectrophotometric method for determination of metformin hydrochloride from bulk as well as dosage form. The present investigation reports a simple UV- spectrophotometric method for the analysis of Metformin hydrochloride in bulk as well as in pharmaceutical formulation. Metformin hydrochloride has high water solubility¹¹.

MATERIAL AND METHODS:

A UV- Spectrophotometer Jasco V-550 UV/VlS Spectrophotometer with 1cm matches quartz cells was used. Pure Metformin hydrochloride was obtained as a gift sample from Litaca Pharmaceuticals Ltd Pune. The tablets of different batches were purchased from the market (recent manufactured). Metformin hydrochloride (10mg) was accurately weighed and dissolved in distilled water so as to give a stock solution of concentration of 100ug/ml. Aliquots of stock solution were transferred into series of 10ml of volumetric flasks and volume was adjusted with distilled water to give final concentration of 10, 20, 30, 40, 50 µg/ml. The absorbance was measured at 232nmagainst distilled water as a blank. We have taken a scan from 200 to 400nm and we found maximum absorbance at 232nm. The repeated experimentation revealed the same wavelength to be the best is not interfering to the analysis of said product because of any extraneous factors like solvent, analysis condition.

The proposed method was applied to the analysis of commercially available Metformin hydrochloride pharmaceutical formulation. A volume equivalent to 10mg of Metformin hydrochloride was transferred into 100ml volumetric flask. A small volume of distilled water was added and shaken well to dissolve.

Table 1: Results of analysis.

Pharmaceutical Formulation	Label claim(mg)	Amount found	% Recovery	Standard deviation	Coefficient of variation
Batch A	500mg	495mg	99.8%	0.0602	0.0493
Batch B	500mg	490mg	99.5%	0.0271	0.8041
Batch C	500mg	499mg	99.9%	0.0382	0.7231

Mean of six determinations

Fig 1: Calibration curves for marketed Metformin hydrochlorideTablet.

It was made up to volume and the solution is filtrate. The filtrate was further diluted with distilled water to 10ug/ml concentration and the absorbance measured at 232nm against distilled water as a blank.

Recovery studies were carried out by adding a known quantity of pure drug (1mg/ml) to pre analyzed formulation and the proposed method was followed. From the amount of drug found, percentage recovery was calculated.

RESULTS AND DISCUSSION:

The proposed method of determination of Metformin hydrochloride showed of 1.0781 ×10 ⁴l/mol.cm. Linear regression of absorbance on concentration gave the equation Y= 0.011X +0.0478 with a correlation coefficient of 0.9778 for marketed tablet. Relative standard deviation of 0.004, 0.006, and 0.002 (for each batch) were observed for analysis of six replicate sample, indicating precision and reproducibility. Metformin hydrochloride exhibits maximum absorption at 232nm and obeyed Beer’s Law in the concentration range 10-50 µg/ml. The results of analysis and recovery studies are presented in Table 1. The percentage recovery value 99.8, 99.5 and 99.9 (for each batch) indicates that there is no interference from the excipients present in the formulation.

CONCLUSION:

The developed method was found to be sensitive, accurate, precise and reproducible and can be used for routine quality control analysis of Metformin hydrochloride in bulk drug and pharmaceutical formulation. This method is not reported yet and tried for the first time. The methods may

Fig 2: Calibration curves for pure drug (Metformin hydrochloride)

have an impact on pharmacological or pharmaco-kinetic studies.

REFERENCES:

1. Sweetman SC. Martindal: the complete drug reference.34^th ed. London Pharmaceutical Press. 2005.

2. Thatcher SP. COS: The Hidden Epidrmic,Perspective Press. 2000.

3. Stepensky D, Friedman M, Srour W, Raz I and Hoffman. A. Preclinical evaluation of pharmacokinetic-pharmacodynamic rationale for oral CR metformin formulation. J.Control.Rel. 2001; 71: 107-115.

4. Physicians’ Desk Reference, Volume 57, Medical Economics Company, Inc., New Jersey, USA, 2003.

5. Balan G, Timmins P, Green DS, Marather PH. In vitro – in vivo Correlation (IVIV) Models for Metformin after Administration of Modified Release (MR) Oral Dosage Forms to Healthy volunteers. J.Pharm.Sci. 2001; 90(8): 1176-1185.

6. Gusler G, Gorsline J, Levy G, Zhang S, Weston, IE, Naret D and Berner B. Pharmacokinetics of Metformin Gastroretentive Tablets in Healthy volunteers. J.Clin.Pharmacol. 2001; 41: 655-661.

7. Yuen KH and Peh K. Simple High-performance liquid chromatographic method for the Determination of Metformin in Human Plasma. J.Chromatogr.B. 1998; 710: 243-246.

8. Taub ME, Kristensen L and Frokjaer S. Optimized Conditions for MDCK permeability and Turbidometric solubility studies using compounds representative of BCS classes I-IV. Eur.J.Pharm.Sci. 2002; 15: 331-340.

9. Block LC, Schemling LO, Couto AG, Mourao SC, Bresolin MB. Pharmaceutical equivalence of metformin tablets with various binders. Rev. Cienc. Farm. Basica Apl ISSN 1808-4532. 2008; 29: 29-35.

10. Damico,C et al. Eds. Nursing, Drug Handbook.22^nd Ed, Sprininghouse Publishers. 2002.

11. Basak SC, Kumar KS, Ramalingam M. Design and release characteristics of sustained release tablet containing metformin hydrochloride Revista Brasileira de Ciencias Farmaceuticas Brazilian Journal of Pharmaceutical Sciences 2008; 44: 477-483.

Received on 13.05.2009 Modified on 15.07.2009

Research J. Pharm. and Tech.2 (4): Oct.-Dec. 2009; Page 874-875