Simultaneous Spectrophotometric Estimation of Omeprazole and Ondansetron Hydrochloride by First Order Derivative Spectroscopy Method in Combined Dosage Form.

 

Reshma Kolte*, Vrushali Tambe, Vijaya Vichare and Manaswi Patil

Modern College of Pharmacy (for Ladies), Dehu-Alandi Road, Borhadewadi, Moshi, Pune-412105.

ABSTRACT:

A  simple, accurate  and  reproducible first order spectrophotometric  method,  requiring  no prior  separation,  has  been  developed and validated  for  the estimation  of Omeprazole (OME) and Ondansetron (OND)  in combined dosage form. First order derivative spectroscopy method was adopted to eliminate spectral interference. It was developed using wavelengths 309.8 nm and 275 nm as zero crossing points for estimation of OME and OND respectively. The method obeys Beer’s Law in concentration range of 5-100µg/ml. The results of analysis have been validated statistically and recovery studies confirmed the accuracy of the proposed method.

 

 

 

INTRODUCTION:

Ondansetron (OND) chemically is 1, 2, 3, 9-tetrahydro-9-methyl-3-[(2-methyl-1H- imidazol-1-yl)-methyl]-4H-carbazol-4-one monohydrochloride, is a selective serotonin 5-HT₃ – receptor antagonist used as an antiemetic, used in the management of nausea and vomiting induced by cytotoxic chemotherapy and radio therapy and also post operative nausea and vomiting^1-7. It is official in IP, USP ^10,11. Analytical methods have been reported for estimation of OND alone or in combination with other drugs in pharmaceutical formulations which include methods like simultaneous UV spectrophotometric methods^1,2,3, HPLC^4,5,6, HPTLC^7,8 and Capillary Zone Electrophoresis⁹. Spectrophotometric method reported are Simultaneous equations using Cramer’s Rule and Multicomponent mode of analysis.

 

Omeprazole (OME) chemically is 5-methoxy-2-[[(4-methoxy-3, 5-dimethyl-2-pyridinyl) methyl] sulfinyl]-1Hbenzimidazole, is  substituted benzimidazole sulfoxides  that  function  as proton  pump  inhibitors and used in the treatment of gastro-esophageal reflux disease (GERD),  peptic  ulcer  and Zollinger-Ellison  syndrome. Omeprazole suppresses gastric acid secretion by H+/K+-ATPase enzyme system at the secretory surface of the gastric parietal cell. It is used for the treatment of duodenal, gastric and esophageal ulceration ^1-9.

 

Omeprazole is official in IP, USP ^12,13. Analytical methods have been reported for estimation of OME alone or in combination with other agents in pharmaceutical formulations and biological fluids like HPLC ^6,14,15  and LC-MS¹⁶, simultaneous UV spectrophotometric methods¹⁷ and  HPTLC¹⁸ .

 

The  objective  of  this investigation  is  to  develop  and validate simple, accurate  and  economical  UV- First order derivative spectroscopic method for estimation of  OME and OND in solid dosage form.

 

MATERIAL AND METHODS:

Instrumentation:

Spectral measurements were made on Shimadzu UV spectrophotometer -1800 model using 10 mm matched quartz cells. All the weighing was done on single pan electronic balance (model Shimadzu AUW-220D).

 

Reagents and chemicals:

Pure drug sample of OME and OND was kindly supplied as a gift sample by Cipla Ltd.

Distilled water and Methanol AR Grade (Merck) were used as solvent.

 

First Order Derivative Method

Determination of absorptivity values:

Standard stock solutions of Omeprazole and Ondansetron were prepared by separately dissolving 10 mg of each drug in methanol, sonicated for 15 min. and diluted to 100 ml with Methanol.

 

Figure 1: Overlay spectra of OME and OND.

 

Figure 2: Calibration Curve for Ondansetron at 275nm and Omeprazole at 309.8.

 

Figure 3: It shows overlay of derivative spectra of Ondansetron.

 

 

Figure 4: It shows overlay of derivative spectra of Omeprazole.

 

Figure 5: It shows overlay of derivative spectra of OME and OND.

 

Both stock solutions were diluted separately to obtain concentration range of 5-30 µg/ml scanned in the spectrum mode from 200 to 400 nm. From the overlain spectra (Figure 1), first order derivative spectroscopy method was selected for the analysis of both the drugs. The spectrums were converted to first order derivative spectra (Figure 3, 4 and 5) by using derivative mode with 21 data point.  From the derivative overlain spectra 309.8 nm and 275 nm were selected as wavelengths of measurements for OME and OND respectively. At 309.8 nm OME had considerable absorbance and OND showed zero absorbance.

 

 

Table 1:  Results of Linearity data for OME and OND                                

Sr. No.	Parameters	OME	OND
1	Linearity μg /ml)	5-30	5-30
2	Correlation Coefficient (R2)	0.996	0.999

 

 

Table 2: Results of assay results for the determination of OME and OND in the tablet formulation

Drug	Label Claim (μg/ ml)	Amount Found (μg/ ml)	% label Claim	S. D. (±)
OME	40	40	100	0
OND	100	100	100	0

n=6

 

At 275 nm OND had good absorbance and OME showed zero absorbance. The calibration curves were plotted for both the drugs at selected wavelengths and the regression equation was computed.

 

Determination of Linearity:

Standard stock solution of pure drugs containing 20 mg of Omeprazole and 8 mg of Ondansetron was prepared in methanol, sonicated for 15 min. and diluted to 100 ml with methanol. The working standard solutions were obtained by dilution of the stock solution in distilled water.

 

Series of solutions containing 5–100 µg/ml of OME and 2-40 µg/ml of OND respectively were used to determine linearity of the method. Solutions were scanned and converted to first order derivative spectra. The values of amplitudes for OME and OND were measured at respective wavelengths.

 

Formulation Assay:

Twenty marketed tablets were weighed and crushed to fine powder. Powder equivalent to 20 mg of OME and 8 mg of OND weighed and mixed with small quantity of methanol, sonicated for 15 min. and diluted to 100 ml with Methanol. The solution was then filtered through Whatmann filter paper No. 41. Appropriate aliquots were taken for further analysis. Absorbance was measured at 309.8 nm and 275 nm and concentration of OME and OND was determined from respective calibration curves.

 

RESULTS AND DISCUSSION:

The developed First order derivative spectrophotometric method for simultaneous determination of Ondansetron and Omeprazole in tablet formulation was found to be simple and convenient for the routine analysis of two drugs. The method is used to eliminate the spectral interference from one of the two drugs while estimating the other drug by selecting the zero crossing point on the derivative spectra of each drug as the selected wavelength. Reason for not using simultaneous equation and absorbance ratio methods were not used as there is maximum spectral overlap and more difference in the absorbance in their marketed ratio.  The proposed method is accurate, precise and reproducible which can be well understood from validation data as given in Table 1 to 4. The % R.S.D. was found to be less than 2, which indicates the validity of methods. Linearity was observed by linear regression equation method for OME and OND in different concentration range. The Correlation coefficient of these drugs was found to be close to 1.00, indicating good linearity in Figure 2.The assay results obtained by proposed methods as shown in Table 2 are in best agreement; hence it can be used for routine analysis of two drugs in combined dosage forms. The method is accurate, simple, rapid, precise, reliable, sensitive, reproducible and economic and is validated as per ICH guidelines.

 

 

Table 3: Results of Recovery studies:

Level of % recovery	Amount present     µg/ml		Amount of standard added    µg/ml		Total amount recovered µg/ml		%Recovery
	OME	OND	OME	OND	OME	OND	OME	OND
50	10	4	5	2	15	6	100	100
100	10	4	10	4	20	8	100	100
150	10	4	15	6	25	10	100	100

n=6

 

 

Table 4: Results of Precision study:

Analyte	Label claim (µg/ml)	Amount estimated (µg/ml)	% label claim ± SD
OME	15	15	100±0.0
OND	6	6	100±0.0

n=6

 

CONCLUSION:

The proposed method is simple, precise, accurate and rapid for the determination of OME and OND in combined tablet dosage forms. This method can be adopted as an alternative to the existing spectrophotometric methods. It can be easily and conveniently adopted for routine quality control analysis.

 

ACKNOWLEDGEMENTS:

The authors are thankful to Cipla Ltd. for providing gift sample of drugs for this work and Modern College of Pharmacy for Ladies, Moshi for providing necessary facilities.

 

 

REFERENCES:

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Received on 12.05.2012        Modified on 24.05.2012

Accepted on 15.06.2012        © AJRC All right reserved