Keywords
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| Ramipril, Absorption Maxima Method, Area under curve. |
Introduction
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| Ramipril is an angiotensin?converting enzyme (ACE) inhibitor. It acts on the renin–angiotensin aldosterone system. It inhibits the conversion of the inactive angiotensin?I to the highly potent vasoconstrictor angiotensin?II, and also reduces the degradation of bradykinin. Ramipril is chemically2?[N?[(S)?1?(ethoxycarbonyl)?3?phenylpro pyl)] ?L?alanyl]?(1S,3S,5S)?2?azabicyclo[3?3?0] octane carboxylic acid [1]. The drug is official in British Pharmacopoeia, which describes a potentiometric titration procedure for its assay in bulk and dosage form [2]. Publications concerning with determination Ramipril, viz: The estimation of ramipril along with hydrochlorothiazide in binary mixture was performed by derivative compensation technique [3] as well as zero crossing derivative technique [4, 5 ]. Chromatographic method involves GC [6, 7], HPLC [8, 9], enzymatic assay with GC or HPLC [10], and radioimmunoassay [11]. All the reported methods are laborious, time-consuming and require highly sophisticated instrumentation [2-11]. Among the various methods available for the determination of drugs, spectrophotometry continues to be very popular, because of their simplicity, specificity and low cost. This study presents new spectrophotometric methods for the determination of ramipril in tablets. |
Material and Methods
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| Instrumentation |
| A Double beam UV?Visible spectrophotometer (Jasco V 530) with 10mm matched quartz cells was used. All weighing were done on single pan balance (Shimadzu). |
| Reagents and chemicals |
| RAM reference standards were kindly provided by Emcure Pharmaceuticals Pvt. Ltd, Pune. Analytical grade methanol was purchased from Merck Specialities Private Ltd., Mumbai. All the reagents were of analytical grade. Glass double distilled water was used throughout the experiment. Tablets were purchased from local market each containing 2.5 mg of RAM. |
| Preparation of standard stock solutions and calibration curve |
| Standard stock solution of pure drug containing 50 μg mL?1 of RAM prepared in methanol distilled water system. The working standard solutions of the drug were obtained by dilution of the stock solution in the distilled water. Series of solutions with conc. 0.1?4 μg mL?1 of RAM were used to prepare calibration curve. Solutions were scanned and proposed methods were applied. |
| Preparation of sample stock solution and formulation analysis |
| A quantity of powder from twenty tablets equivalent to 50mg of RAM was weighed and transferred to a flask containing 10 ml of methanol and ultrasonicated for 15 min and solution was filtered through Whatman paper No. 41 into a 100 mL volumetric flask. Volume was made up with distilled water. The solution was further diluted with distilled water to get 2.5 μg mL?1 of RAM. |
| Method A: Absorption Maxima Method |
| For the selection of analytical wavelength, 2.5 μg mL?1 of RAM was prepared by appropriate dilution of standard stock solution and scanned in the spectrum mode from 400 nm to 200 nm. From the spectra figure 2 of drugs Lmax of RAM 210 nm was selected for the analysis. The calibration curve was prepared in the concentration range of 0.1? 4 μg/ mL at 210 nm. By using the calibration curve, the concentration of the sample solution was determined. The result shown in table no. 2. |
| Method B: Area under curve |
| For the determination using the area under curve (AUC) method, suitable dilutions of the standard stock solutions of RAM were prepared in methanol distilled water system. The solution of drugs was scanned in the range of 200?400 nm. From the spectra figure 3 of drugs Lmax for estimation of RAM 202? 237.5nm was selected for the analysis. The calibration curve was plotted in the concentration range of 0.1? 4 μg/ mL. This showed linear response with increasing concentration hence the same wavelength range was used for estimation of tablet formulations. The result shown in table no. 2. |
| Result: |
| Method validation |
| The Method was validated as per ICH guidelines using different parameter. |
| Linearity: |
| The linearity was evaluated by analyzing different concentration of standard solution of RAM. The Beer Lambert’s law was obeyed in the concentration range of 0.1? 4 μg/ mL for both method with regression coefficient of 0.9991 and 0.9998 for method A and method B respectively. |
| Limit of Detection and Limit of Quantitation |
| LOD and LOQ were calculated from the data obtained from the linearity studies. The slope of the linearity plot was determined. For each of the six replicate determinations, y intercept was calculated and the standard deviation of the y intercept was computed. From these values, the parameters Limit of Detection (LOD) and Limit of Quantitation and (LOQ) were determined on the basis of response and slope of the regression equation. The result was given table no 1. |
| Precision: |
| Six replicate analyses of tablets by the proposed method were done. The results of the precision study indicate that the method is reliable. The intermediate precision (inter-day precision) of the method was also evaluated using two different analysts in different days in same laboratory. Results are shown in table 3. Intraday and interday precision was carried out with 99.67% results. |
| Accuracy (Recovery studies) |
| Accuracy of the method was studied by recovery experiments. The recovery experiments were performed by adding known amounts of the drugs. The recovery was performed at three levels, 80%, 100% and 120% of the label claim of the tablet. The result shown in table no. 4. |
| Discussion |
| The proposed methods for estimation of RAM in pharmaceutical dosage form were found to be accurate, simple and rapid. Hence it can be used for routine analysis of these drugs in pharmaceutical dosage forms. There was no interference from tablet excipients was observed in these methods. The values of % RSD and correlation of coefficient were found to be (% RSD 0.49? 1.08) and correlation coefficient was 0.9991 and 0.9998 for RAM. The result of recovery studies for tablet was found to be in the range of 98.40 ?100.96% for method A, 99.02?100.89 for method B. Values are reported in Table 4. It indicates that there is no interference due to excipients present in the formulation. It can be easily and conveniently adopted for routine quality control analysis. Both methods are accurate, simple, rapid, precise, reliable, sensitive, reproducible and economic and are validated as per ICH guidelines. |
| Conclusion |
| The results of our study indicate that the proposed UV spectroscopic methods are simple, rapid, precise and accurate. The developed UV spectroscopic methods were found suitable for determination of RAM in bulk drug and in marketed solid dosage formulation without any interference from the excipients. Statistical analysis proves that, these methods are repeatable and selective for the analysis of RAM. It can therefore be concluded that use of these methods can save much time and money and it can be used in laboratories with accuracy. |
| Acknowledgement |
| The authors are very much thankful to the Chairman, Pdmashree Mrs. Fatma Rafiq Zakaria, Maulana Azad Educational Trust, for providing necessary facilities for the project work. |
Tables at a glance
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Table 3 |
Table 4 |
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Figures at a glance
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