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Estimation of ibuprofen and famotidine in tablets by second order derivative spectrophotometery method
⁎Corresponding author. Tel.: +91 9824372379. dimalgroup@yahoo.com (Dimal A. Shah)
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Received: ,
Accepted: ,
This article was originally published by Elsevier and was migrated to Scientific Scholar after the change of Publisher.
Peer review under responsibility of King Saud University.
Abstract
A simple and accurate method for the analysis of ibuprofen (IBU) and famotidine (FAM) in their combined dosage form was developed using second order derivative spectrophotometery. IBU and FAM were quantified using second derivative responses at 272.8 nm and 290 nm in the spectra of their solutions in methanol. The calibration curves were linear in the concentration range of 100–600 μg/mL for IBU and 5–25 μg/mL for FAM. The method was validated and found to be accurate and precise. Developed method was successfully applied for the estimation of IBU and FAM in their combined dosage form.
Keywords
Ibuprofen (IBU)
Famotidine (FAM)
Second order UV spectrophotometry
Validation
1 Introduction
Ibuprofen (IBU) is chemically, (RS)-2-(4-(2-methylpropyl)phenyl)propanoic acid (O'Neil, 2001). The empirical formula of IBU is C13H18O2 and a molecular weight of 206.2 g/mole (Fig. 1). It is a non steroidal anti-inflammatory drug and it inhibits prostaglandin biosynthesis by blocking the enzyme cyclooxygenase, which converts arachidonic acid to prostaglandin. It is used as analgesic, antipyretic and anti-inflammatory drug (Rang and Dale, 2003). Famotidine (FAM) is chemically 3-[({2-[(diaminomethylidene)amino]-1,3-thiazol-4-yl}methyl)sulfanyl]-N′-sulfamoylpropanimidamide. It has an empirical formula of C8H15N7O2S3 and a molecular weight of 337 g/mole (Fig. 1). It is a histamine-2 receptor blocker. Histamine stimulates cells lining of stomach to produce acid. Famotidine blocks the action of histamine on stomach cells, thus reducing the production of acid by the stomach (Rang and Dale, 2003). Ibuprofen is used as anti-inflammatory and analgesic drug while famotidine reduces gastric acid secretion. By combining ibuprofen and famotidine, the gastrointestinal side effects produced by ibuprofen is reduced by famotidine without altering its ability to reduce pain and inflammation. The combined formulation is indicated for the treatment of rheumatoid arthritis and osteoarthritis and to decrease the risk of developing upper gastrointestinal ulcers.
Structure of (A) ibuprofen and (B) famotidine.
Ibuprofen is official in Indian Pharmacopoeia, British Pharmacopoeia and United state Pharmacopoeia. A literature survey regarding quantitative analysis of these drugs revealed that attempts have been made to develop analytical methods for the estimation of ibuprofen alone and in combination with other drugs by liquid chromatographic (LC) (Indian Pharmacopoeia, 2007; British Pharmacopoeia, 2009; United States Pharmacopoeia and National Formulary, 2004; Reddy and Reddy, 2009), HPTLC (Chitlange et al., 2008; Sam Solomon et al., 2010; Rele and Sawant, 2010), super critical fluid chromatography (Bari et al., 1997) and spectrophotometric methods (Gondalia et al., 2010). Famotidine is official in British Pharmacopoeia and United state Pharmacopoeia. Literature survey revealed that liquid chromatographic (LC) (Sultana et al., 2011), HPTLC (Novaković, 1999) and spectrophotometric methods (Kanakapura et al., 2011) have been reported for the estimation of famotidine.
There is no method reported for the estimation of IBU and FAM in combined dosage form. Present study involves the development and validation of second order derivative spectrophotometric method for the estimation of IBU and FAM in combined dosage form.
2 Experimental
2.1 Apparatus
2.1.1 Spectrophotometer
All the absorption spectra and derivative spectra were recorded on UV–visible double beam spectrophotometer (UV-1700, Shimadzu Corp., Japan) with 1 cm quartz cell.
2.1.2 Electronic balance
All the drugs and chemicals were weighed on Shimadzu electronic balance (AX 200, Shimadzu Corp., Japan).
2.2 Reagents and materials
2.2.1 Pure samples
Analytically pure FAM and IBU were obtained as gift samples from Blue Cross Laboratory Limited, Mumbai, India and Mercury Laboratories Limited, Vadodara, India, respectively. The purity of IBU and FAM were found to be 99.32%, and 99.45% respectively, according to the manufacturer's analysis certificates.
2.2.2 Market samples
Tablet formulation (DUEXIS, Horizon Pharma, USA) containing labeled amount of 800 mg of ibuprofen and 26.6 mg of famotidine was used for the study.
2.2.3 Chemicals and reagents
Methanol (E. Merck, Mumbai, India) used as a solvent was of analytical grade.
2.3 Second order derivative spectrophotometric method
2.3.1 Preparation of standard stock solutions
Stock solutions were prepared by weighing 25 mg each of IBU and FAM and transferring to 2 separate 25 mL volumetric flasks. Volume was made up to the mark with methanol, which gave 1000 μg/mL of both the drugs. Aliquot from the stock solutions of FAM was appropriately diluted with methanol to obtain the working standard of 100 μg/mL of FAM.
2.3.2 Selection of wavelengths
Working standard solutions of IBU and FAM were diluted appropriately with methanol to obtain solution containing 100 μg/mL of IBU and 10 μg/mL of FAM. Spectra of above solutions were scanned in the spectrum mode between 200 and 400 nm, with a bandwidth of 2 nm. These zero order spectra of IBU and FAM were treated to obtain corresponding second order derivative spectra with an interpoint distance of 8 nm and scaling factor of 100.
Using memory channels, the second order derivative spectra were overlapped. The zero crossing point (ZCPs) values of IBU at which the FAM showed derivative response were recorded. The wavelength of 290 nm was selected for the quantification of FAM (where the derivative response for IBU was zero). Similarly, 272.8 nm was selected for the quantification of IBU (where the derivative response for FAM was zero). Characteristic wavelengths (ZCPs) for IBU and FAM were confirmed by varying the concentration of both drugs.
2.3.3 Calibration curves for IBU and FAM
The working standard solutions of IBU and FAM were used to prepare two different sets of diluted standards. Appropriate aliquots of IBU and FAM working standard solutions were taken in different 10 mL volumetric flasks and diluted up to the mark with methanol to obtain final concentrations in the range of 100–600 μg/mL of IBU and 5–25 μg/mL of FAM, respectively. Spectra of the solutions were scanned between 200 and 400 nm and were treated to obtain the corresponding second order derivative spectra. Calibration curves were constructed relating the peak amplitude at 272.8 nm and at 290 nm to the corresponding concentrations and regression equations were computed for IBU and FAM. All the spectrophotometric estimations were carried out at controlled room temperature (20–25 °C).
2.3.4 Method validation
The method was validated as per ICH guidelines for accuracy, precision, specificity and robustness by following procedure.
2.3.4.1 Accuracy
The accuracy of the method was determined by calculating recoveries of IBU and FAM by the method of standard additions. The known amounts of IBU (0, 80, 160, 240 μg/mL) and FAM (0, 2.5, 5, 7.5 μg/mL) were added to a pre quantified sample solution, and the amount of IBU and FAM was estimated by measuring derivative response at the appropriate wavelengths. The recovery was verified by the estimation of drugs in triplicate preparations at each specified concentration levels.
2.3.4.2 Precision
The repeatability (intra-day) and intermediate precision (inter-day) study of the proposed first derivative spectrophotometery method were carried by estimating the corresponding derivative responses three times on the same day and on 3 different days (first, second, third day) for three different concentrations of IBU (100, 400, 600 μg/mL) and FAM (5, 10, 25 μg/mL), and the results are reported in terms of relative standard deviation (RSD).
The repeatability studies were carried out by analyzing IBU (300 μg/mL) and FAM (10 μg/mL) six times and results are reported in terms of relative standard deviation.
2.3.4.3 Specificity
For specificity study commonly used excipients present in selected tablet formulation were spiked into a pre weighed quantity of drugs. The absorbance was measured and the quantities of drugs were determined. The excipients used were talc, micro crystalline cellulose, starch (S.D. Fine Chemicals, India) and carboxy methyl cellulose (Allied Chemical Corporation, India).
2.3.4.4 Robustness
Robustness of the method was studied by observing the stability of both the drug solutions at 25 ± 2 °C for 24 h.
2.3.5 Laboratory prepared mixtures
Appropriate aliquots of IBU working standard solutions were taken in different 10 mL volumetric flasks. To the same flask appropriate aliquots of FAM working standard solutions were added and the volume was diluted to the mark with methanol to achieve final concentration of 100, 200, 400, 600 μg/mL of IBU and 5, 10, 20, 25 μg/mL of FAM.
Spectra of the solutions were scanned and corresponding second order derivative responses were measured at 272.8 nm and 290 nm.
2.3.6 Analysis of marketed formulations
Twenty tablets were weighed accurately and finely powdered. Tablet powder equivalent to 800 mg IBU (and 26.6 mg of FAM) was taken in a 100 ml volumetric flask. Methanol (50 ml) was added to the above flask and the flask was sonicated for 10 min. The solution was filtered using Whatman filter paper No. 41 and the volume was made up to the mark with the methanol.
Appropriate volume of the aliquot was transferred to a 10 ml volumetric flask and the volume was made up to the mark with the methanol to obtain a solution containing 320 μg/mL of IBU and 10.64 μg/mL of FAM. The solution was sonicated for 10 min. The absorbances were noted at respective wavelength. The amounts of IBU and FAM were determined by fitting the derivative responses into the equation of straight line representing the calibration curves for IBU and FAM.
3 Results and discussion
3.1 Derivative spectrophotometric method
Fig. 2 shows overlaid zero order spectra of IBU and FAM in methanol. FAM significantly contributes to the absorbance of IBU at the maximum absorbance value so, derivative method was selected for the estimation of IBU and FAM in the presence of each other. The second order derivative spectra (D2) of IBU and FAM showed a ZCPs of IBU at 290 nm where FAM gives significant derivative response, while the D2 spectrum of FAM has zero absorbance at 272.8 nm where IBU gives significant derivative response (Fig. 3). The ZCPs of both the drugs remained constant and no shift was observed. Therefore, 272.8 nm was selected for the estimation of IBU and 290 nm was selected for the estimation of FAM.
Zero order overlay spectra of ibuprofen and famotidine.
Second order overlay spectra of ibuprofen and famotidine.
With an increase in the concentration of IBU, the derivative response at 272.8 nm increased. The responses for IBU were found to be linear in the concentration range of 100–600 μg/mL, with a correlation coefficient of 0.9992. Similarly, the derivative responses for FAM at 290 nm were linear in the concentration range of 5–25 μg/mL with r = 0.9990. The regression analysis of the calibration curves is shown in Table 1.
Parameter
IBU
FAM
Linearity (μg/mL)
100–600
5–25
Correlation coefficient (r)
0.9992
0.9990
Slope of regression
0.001
0.0168
Standard deviation of slope
0.0002
0.0004
Intercept of regression
0.0214
0.0204
Standard deviation of intercept
0.009476
0.005783
The recoveries of IBU and FAM were found to be in the range of 99.86–100.37% and 98.83–100.15%, respectively, which are satisfactory. Precision studies were carried out to study the intra-day and inter-day variability of the responses. The low RSD value indicates that the method is precise (Table 2). Excipients used in the specificity studies did not interfere with the derivative response of either of the drugs at their respective analytical wavelengths. In robustness study, no significant change in the derivative response of both the drugs was observed after 24 h and the percentage recovery for IBU and FAM were found to be more than 98% for both the drugs. The validation parameters are summarized in Table 2.
Parameters
IBU
FAM
Detection limit (μg/mL)
31.27
1.13
Quantitation limit (μg/mL)
94.76
3.44
Accuracy (%)
99.86–100.37
98.83–100.15
Precision (RSD,a %)
Intra-day precision (n = 3)
0.23–1.28
0.39–1.07
Inter-day precision (n = 3)
0.12–1.46
0.22–1.54
Repeatability study (n = 6)
0.45
0.63
The proposed method was valid for the determination of IBU and FAM in different laboratory prepared mixtures with mean recoveries as shown in Table 3. The mean recoveries indicate that the method is accurate and precise.
Sr. No.
IBU
FAM
Amt. takena
% found ± SDb
Amt. takena
% found ± SDb
1
100
97.14 ± 0.92
5
99.71 ± 1.03
2
200
99.34 ± 1.78
10
98.45 ± 0.82
3
400
98.56 ± 0.47
20
101.12 ± 1.15
4
600
98.45 ± 1.28
25
97.62 ± 1.53
The proposed method was applied for the determination of IBU and FAM in their combined tablet dosage forms. The results obtained were comparable with the corresponding labeled amounts (Table 4).
Formulations
Labeled amount (mg)
% Recoverya
IBU
FAM
IBU
FAM
A
800
26.6
99.81 ± 0.72
99.56 ± 1.37
4 Conclusion
A second order derivative spectrophotometery method has been developed for the estimation of IBU and FAM in their combined dosage form. The method was validated and found to be simple, sensitive, accurate and precise. Second order derivative spectrophotometric method is having advantages that it is simple, requires less analysis time and the cost of analysis is less compared to chromatographic method. The method was successfully applied in the estimation of IBU and FAM in their combined dosage form.
Acknowledgements
The authors are thankful to the Mercury Pharmaceuticals Ltd., Baroda and Blue Cross Laboratory, Mumbai, India for providing gift sample of IBU and FAM, respectively. The authors are very thankful to the Principal, Indukaka Ipcowala College of Pharmacy, New Vallabh Vidyanagar for providing necessary facilities to carry out the research work.
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