Spectrophotometric Estimation of Omeprazole in Pharmaceutical Dosage Form

Rakesh Singh and Swarnlata Saraf*

Institute of Pharmacy, Pt. Ravishankar Shukla University, Raipur 492 010 (CG) India

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

ABSTRACT

Zollinger Ellison syndrome, chronic peptic ulcer, and GERD are the disease condition which require to administered drug for a long period. Omeprazole belongs to the class of proton pump inhibitors widely used for such disease conditions. A simple, accurate, rapid, sensitive and economical spectrophotometric method for the determination of omeprazole in its pharmaceutical dosage forms has been developed. Omeprazole shows absorption maxima at 298.4 nm and obeyed Lambert Beer’s law in the concentration range of 2-18µ g/ml in the 6.8 phosphate buffer. The accuracy and reproducibility of the proposed method was statistically validated by recovery studies.

KEY WORDS Omeprazole, spectrophotometric method, Proton pump inhibitor.

INTRODUCTION:

Proton pump inhibitors (PPIs) have dramatically influenced the management of acid-peptic disorders in recent years1. Omeprazole is 6-methoxy-2-[(4- methoxy-3, 5-dimethylpyridin-2-yl)methylsulfinyl]- 1H-benzimidazole, is powerful inhibitor of gastric acid secretion in normal healthy subjects2 and in patient with duodenal ulcer.3 Omeprazole is official in I.P 1996.4 Macek J et al had estimated omeprazole in human plasma by protein precipitation and liquid chromatography-tandem mass spectrometry.5 Hultman La et al had determined omeprazole by liquid chromatography with tandem mass spectrometry.6 I.P (1996) suggests HPLC method for the estimation of omeprazole in bulk drugs. As no UV- spectrophotometric method reported for the estimation of the omeprazole in pharmaceutical dosage forms, and there are number of formulations available in market, which contain these drugs. In this present work a very simple and economic UV spectrophotometric method has been reported.

MATERIAL AND METHODS:

UV-Spectrophotometer (Systronic 2202, India) was used for experiments. All the chemicals used during experimentation were of analytical grade. The commercially available tablets of omeprazole were procured from local market.

Preparation of standard solutions:

Stock solution of omeprazole was prepared by dissolving 20mg (accurately weighed) of standard omeprazole in 10ml of 6.8 phosphate buffer. This was further diluted to get a working standard stock solution of 200 µ g/ml. Then 1,2,3,4…..10ml of working standard solution were transferred into a series of 10ml volumetric flasks. The volume made up with 6.8 phosphate buffer solution. Then the sample was scan in UV range (200-400), Peak maxima were observed at 298.4 nm (fig 1). The absorbance of the solution was measured at 298.4 nm against blank, and the calibration curve plotted.

Estimation from tablet

Average weight of twenty tablets was determined and these were then finely powdered (separately for each formulation tested). The powdered amount equivalent to 100mg (accurately weighed) was dissolved in 100 ml of 6.8 phosphate buffer and sonicated in bathsonicator for 10 min. Then filtered 1ml of above solution was transferred to 10ml volumetric flask and volume made up and drug content was determined from the calibration curve.

Fig 1. UV spectra of omeprazole in 6.8 phosphate buffer for determination of λmax

Table-1: Result of analysis of commercial formulations

Formulations	Amount labeled mg/tab	Amount found mg/tab	SD*	%RSD*	SE*	‘t’ cal*	% recovery
1	20	19.82	0.121	0.6	0.049	1.324	99.56
2	20	19.67	0.143	0.7	0.058	1.981	99.21
3	20	20.02	0.098	0.4	0.04	1.212	99.79

*Average of six determinations; SD=standard deviation; %RSD= Relative standard deviation; SE= standard error.

RESULT AND DISCUSSION:

In the present study, UV spectrophotometric method has been developed for the estimation of omeprazole in pharmaceutical formulations. Optimum operating conditions used in the procedures were established adopting one variable at a time. The absorption maxima was found to be 298.4 nm. The Beer’s law was found in the concentration range of 2-18 µ g/ml. The molar absorptivity was found to be 7.14×103 l/mol/cm and Sandell’s sensitivity was found to be 0.0483 µ g/cm2 × 0.001. The regression equation gives slope of 0.0363 with the intercept at 0.0348. The correlation coefficient was found to be 0.9921. The precision and accuracy of the method was established by measuring six replicate samples of the drug in commercial formulations. None of the excipients of the formulation interfered in the analysis of omeprazole by this proposed method. The results obtained by the proposed method were in good agreement with the labeled amounts. Performing recovery experiments using standard addition method checked the accuracy of the proposed method. In this, known amount of pure drug was added to the previously analyzed samples, and these samples were re-analyzed. The percentage recovery was close to 100% (Table-1). The proposed method is simple, convenient, accurate, sensitive and reproducible. Hence this can be utilized for routine analysis of omeprazole in formulations.

CONCLUSION:

UV spectrophotometric method provides the simplest, accurate, rapid, sensitive and economical spectrophotometric method for the determination of omeprazole in its pharmaceutical dosage forms.

ACKNOWLEDGEMENTS:

The author wishes to thanks AICTE New Delhi and CG-COST for financial assistance under research promotion scheme.

REFERENCE:

1. Rani S, Padh H. Inter-individual variation in pharmacokinetics of proton pump inhibitors in healthy Indian males. Indian J. Pharm. Sci. 2006, 68 (6), 754-759.

2. Howden CW, Forrest JAH, Reid JL. Effect of single and repeated dose of omeprazole on gastric acid and pepsin secretion in man. 1984, 25, 707-710.

3. Walt RP, Gomes M de FA, Wood EC et al. Effect of daily oral omeprazole on 24 hour intragastric acidity. Br Med J. 1983, 287,12-14.

4. Indian pharmacopoeia 1996, Vol 1, Published by the controller of publication, Delhi, P. 532-534.

5. Macek J, Klima J, Ptacek P. Rapid determination of omeprazole in human plasma by protein precipitation and liquid chromatography- tandem mass spectrometry. Journal of chromatography B. 2007, 852, 282-287.

6. Hultman la, Stenhoff H, Liljeblad M. Determination of esomeprazole and its two main metabolites in human, rat and dog plasma by liquid chromatography with tendem mass spectroscopy. Journal of chromatography B. 2007, 848, 317-322.

Received on 12.08.2008 Modified on 22.08.2008

Research J. Pharm. and Tech. 1(3): July-Sept. 2008; Page 276-277