Aspirin investigation

Aspirin investigation

Introduction

Aspirin is a common analgesic drug used to reduce pain. The drug works by inhibiting substances in the body that mediate pain. Fever and inflammatory processes. Sometimes aspirin can be used in the prevention of heart attack, stroke and chest pains. Previous studies have reported successful treatment of heart failure and sinus rhythm. Comparison between aspirin and warfarin singled out aspirin as more superior than warfarin (Homma et al., 2012). The findings of this study showed that aspirin could effectively be used in the treatment of the symptoms of heart failure and reduce pain. However, the continued use of aspirin among patients with congestive heart failure has raised the concern of drug resistance among some patients. Analysis of the treatment outcomes among patients treated with aspirin acquired from different companies has produced varying results. The results implied that the aspirins from the various companies had some variations (Sane, McKee, Malinin, & Serebruany, 2002).

The IUPAC name of salicylic acid is ortho-hydroxybenzoic acid or 2-hydroxybenzoic acid. This compound has been used historically to reduce pain in 400 B.C. Salicylic acids is naturally found in the willow leaves. Pharmaceutical companies use none-polar solvents to extract the compound from the willow leaves and purify it before incorporating in aspirin tablets. Based on the method used for extraction, different concentration of the compounds is obtained and incorporated in the aspirin tablets. Therefore, the extraction methods influence the amount of salicylic acid found in different brands aspirin tablets (Nordström & Rasmuson, 2006).

The crystal structure of salicylic acid forms a monoclinic. This structure was previously elucidated by (Bacon & Jude, 1973). According to the structure generated by Bacon & Jude, intramolecular hydrogen bonding holds the hydroxyl groups to the carbonyl oxygen. The rigid bonding characteristics of the molecule makes the structure to be less flexible and a diminished intramolecular hydrogen bonding capability of the molecule. These structure of the molecule explains the reduced ability of the compound to dissolve in polar solvents (Bacon & Jude, 1973). However, despite the elucidation of the structure, there is only limited information about the solubility of this molecule and the effect of temperature on its solubility.

Chemical analysis of aspirin tablets acquired from different companies shows some differences in the amount of the specific ingredients. More importantly, the salicylic acid, which is the active compound in aspirin varied from company to company (Morgan & Truitt Jr., 1965). Spectrophotometric measurement of acetylsalicylic acid in different aspirin samples has also shown different results. Studies utilizing laboratory animals have also shown that animals have different rates of hydrolyzing acetyl-salicylic acid in serum hence showing that animal treated with aspirin are likely to respond differently. Animals with a higher rate of acetylsalicylic acid hydrolysis showed reduced aspirin utilization as compared to the animals with slower aspirin hydrolysis. To improve the efficacy of aspirin, some manufacturer prefers to elevate the salicylic components of the drugs to make them long-lasting hence, achieving the intended purpose among the animals with a higher salicylic hydrolysis rate (Morgan & Truitt Jr., 1965). The therapeutic index of salicylic should not be exceeded as this can cause toxicity (Arif & Aggarwal, 2019). The safe salicylic drug components and the recommended therapeutic index have been shown in table 1.

Table 1: Amount of salicylic acid in different aspirin brands as estimated by the acetone dissolution method

Salicylic acid is an organic compound containing carbon-hydrogen and oxygen in the structure. The organic compound is soluble in organic solvents such as acetone, ethanol or methanol. In previous studies, salicylic acid has been extracted from aspirin by dissolving in organic solvents (National Center for Biotechnology Information, 2020). Therefore, the dissolution method for salicylic acid isolation from aspirin has bee established and works effectively. This isolation method is simple, less costly and direct. The method does not require specialized skills to perform. The current study will apply the acetone extraction method to estimate the amount of salicylic acid in various aspirin tablet acquired from different companies. The structure of salicylic acid is shown in figure 1.

(Nordström & Rasmuson, 2006)

Chromatographic techniques have also been used in the extraction and determination of the amount of salicylic acid in aspirin. Column chromatography is used to retain salicylic acid complexed on ferric ions in the column, while the other portions of the aspirin are eluted in chloroform. After the complete elution of the non-salicylic acid portion of aspirin, acetic acid is used to free the salicylic acid from ferric column packing. The chromatographic method has been well-established, but it poses some challenges during the process of separation including the slow migration of salicylic acid in the column during the elution of non-salicylic portion; hence some small amount of salicylic acid is lost

The current experiment adopted the acetone dissolution method to extract and estimate the amount of salicylic acid in different aspirin tablets acquired from different manufacturers. The main objective was to determine the difference in salicylic acid concentration in different aspirins from different companies. The experiment hypothesized that aspirin from different companies contains a different level of salicylic acid.

Research question

Is there a significant difference in the amount of salicylic acid in aspirin tablets obtained from different companies?

Methodology

The materials used in the experiment included aspirin tablets, acetone, mortar and pestle, and Buchner funnel.

Experiment procedures

All the 40 tablets were crushed using mortar and pestle and the powdered tablets dissolved in 20 ml of acetone solvent. During the stirring, the beaker was heated. Heating increases the rate at which the aspirin components dissolve in the solvent. The solution was allowed to cool in the open for 1 hour. The cooled solution was vacuum filtered using the Buchner funnel. To recover the acetylsalicylic acid, the filtered solution was evaporated to remove acetone. The acetone method for extraction of salicylic acid from aspirin tablets is useful in the determination of the amount of salicylate in aspirin.

The solubility of salicylate in non-polar solvents such as acetone gives this method the advantage of specificity. The other components of aspirin are polar and hence, cannot dissolve in acetone. This implies that only salicylate dissolved in in acetone and was extracted (Weber & Levine, 1966). The use of acetone method for the estimation of salicylate reduced the number of impurities, which would increase the weight of salicylate; producing inflated figures. Therefore, the accuracy of the method used was high, with a very narrow margin of error.

The limitation of the method used in this experiment is the possibility of obtaining a salicylate extract with incomplete evaporation. Incomplete evaporation would mean that some acetone remains unevaporated, eventually increasing the weight of the resultant salicylic acid. To reduce the error rate caused by incomplete evaporation, the time for drying should be increased. Increasing the evaporation period ensures that no acetone remains in the beaker, increasing the accuracy of the measurements obtained. In addition, cooling the solution for 1 hour before vacuum filtration helps to ensure that most of the unwanted impurities sediments at the bottom of the flask. This way, it is easier to filter the solution and reduce the amount of impurities that would have increased the weight of the extracted salicylic acid.

Raw data

The data is composed of the weights of the crushed tables, sodium hydroxide, flask and the weight of the salicylic acid. The experiment was performed in ten different trials to produce replicate data for estimation of the average weight of the salicylic acid in aspirin. The weight of salicylic acid was determined by subtracting the weight of the conical flask from the total weight and recorded in grams.

Table 1: The raw data derived from the experiment. The data shows information generated from the experiment before data analysis.

Weight of Salicylic acid in aspirins from two different companies

The analysis of the concentration of salicylic acid in tablets obtained from the two different companies revealed significant variations in the concentration of this compound. The highest weight was 4.79 while the lowest was 1.97. See table 2 below. Comparing the two aspirin brands show that square carva had the highest weight of salicylic acid. Seven trials were performed for square carva, and the average concentration was 2.350g. On the other hand, five trials were conducted for the Ecospirin brand giving an average of 1.940 grams of salicylic acid.

Table 2: The concentration of salicylic acid in aspirin tablets obtained from different companies.

Table 2: The amount of salicylic acid present in different brands of aspirin as estimated in various trials. Salicylic acid was determined for Ecospirin and Square carva. Comparison between the two companies revealed that the aspirin from Square carva company had more amounts of salicylic acid compared to Ecospirin.

Graphical representation of the result has been shown in figure 1. Out of the ten trials, trial 7 and 9 were performed for both Ecospirin and Square carva aspirin. In both trials, Square Carva had higher amounts of salicylate. (see figure 1). Three of the remaining trials were performed for Ecospirin, while the other four trials were performed for Square Carva. The result showed that more trials were conducted for Square Carva compared to Ecospirin.

Figure1: This graph shows the ten trials that were performed in the experiment and the relative amounts of salicylic acid obtained in each trial. For trials seven and nine, measurement of salicylic acid was determined for both aspirin companies.

The average weight of Salicylic acid in two aspirin Companies

The mean amount of salicylic acid in the Square Carva brand was higher than that in Ecospirin. These findings confirmed the study hypothesis. The hypothesis that the amount of salicylic acid in different aspirin obtained from various companies are not the same was proved right by the results of this experiment (See figure 2).

Figure 2: The average weight of salicylic acid in the two aspirin brands

Discussion

The findings of the study showed that the amount of salicylic acid in the two brands was not similar. In light of the results obtained from the experiment, the hypothesis that the weight of salicylic acid in aspirin is not identical in aspirin from different companies is accepted. The weight of aspirin in Square Carva was slightly higher than that in Ecospirin (2.35 grams versus 1.95 grams). The difference in weight of salicylic acid was, however, small (0.4 grams). From table one, it is evident that five trials were performed for Ecospirin versus seven trials for Square Carva. The results obtained per trial also supported the hypothesis.

The findings of these experiments are consistent with results of the previous experiment that explored the difference of salicylic acid in aspirin from different companies (Dacić, Uzunović, Kunić, Pilipović, & Šapčanin, 2019). However, despite the substantial agreement of results between the current experiment and other studies, observations about variation in chemistry methods adopted have been made. The dissolution extraction method has been considered to be the best for this type of experiments due to its high accuracy index. However, more accurate and automated methods have been developed. The UV-VIS spectroscopy has been suggested as the best method for determination of acetylsalicylic acid (Dacić et al., 2019). Dacic and colleagues applied the UV-VIS spectroscopy method to estimate the weight of salicylic acid in six aspirin tablets from different manufacturers in Bosnia and Herzegovina. Dacic and colleagues found that there was some disparity in the weight of salicylic acid between the weight declared by the manufacture and the study results. Figure 2 shows the stud findings versus the manufacturers’ declaration.

Figure 2: The weight of salicylic acid measured in six tablets versus the weight declared by the manufacturer.

The fact that some variations were recorded between the manufacturer values and the experimental values supported the findings we reported in our experiment. The study by Dacic and colleagues showed a significant deviation of the weight salicylic acid from the manufacturer’s declaration from 100mg to 104.407mg per tablet. The variation was 4.407mg, which was significantly lower than the value of 0.4 g that our experiment reported.

The implication of our findings in the context of previously published results is that pharmacists may potentially prescribe an overdose or underdose of medication it the manufacturer declared values are not accurate as demonstrated in this experiment. Moreover, our findings reaffirmed that there is always a variation in the content of drugs manufactured by different companies. In this regard, the prescription of salicylic acid-containing medicines from different companies should be prescribed separately based on the amount of the salicylic acid present.

The variations in the amount of salicylic acid present in the drug could be as a result of the difference in principles of techniques applied. The use of different techniques to estimate the amount of salicylic in aspirin can generate some discrepancy in the results, consequently providing misleading information (Iwunze, 2008). Standardization of methods for estimation of active compounds in drugs such as salicylic acid should be considered as a guiding principle. This approach would help to ensure that results from different chemistry laboratories are in agreement.

Currently, HPLC based method for estimation of salicylic acid in aspirin has been developed. The HPLC method is an improved version of chromatography that applies pressured liquid as a mobile phase to dissolve the salicylic acid and move it along separation columns. This action of the HPLC method results in an accurate separation of all components of aspirin. The plans have high resolution with a very low limit of detection (Wanping et al., 2017). The HPLC method was used by Wanping and colleagues in the study aimed at quantifying the amount of salicylic acid in paracetamol and caffeine in aspirin. A non-polar mobile phase was used in this separation to achieve the highest separation resolution. Salicylic acid is soluble in nonpolar solvents dissolved in the acetonitrile-tetrahydrofuran-glacial acetic acid-water (22∶5∶5∶68), used as the mobile phase. Up elution, the eluent was detected using ultra violate light at a wavelength of 303 nm. The injection rate was set at 1.0 ml·min-1. Compared to the method used to extract and identify salicylic acid in our experiment, the HPLC method is highly improved and is automated. This improvement in the functionality of the HPLC method explains the disparity in the values obtained and the values reported in our experiment. The experiment performed using the HPLC method were 1.500-75.000 μg·ml-1. The ability to measure very little weight in the scale of micrograms reflected the high sensitivity of the technique and the low limit of detection. Despite the method being simple and easy to operate, it gave very accurate results demonstrating the potential to improve the methods used in the quantification of the amount of salicylic acid in aspirin. The continuous improvement of the technique can help in ensuring that the accurate doses are prescribed. Comparison of the new HPLC method with the acetone dissolution method showed that the HPLC method is highly versatile and can be used in the determination of more than one molecule at the same time. However, the technique applies the same principle as the acetone method for salicylic acid extraction and determination.

There is a need for further investigations to examine the effect of using a less sensitive method on the results produced. Moreover, future studies should focus on the validation of the acetone method for use as a standard method for the determination of active compounds in drugs as this method remains the most affordable and easy to use the technique. From the findings of our experiment, we recommend that all medications, including aspirin, be subjected to quality control by quantifying the amount of active ingredients before their release in the market. Our experiment provided insight into the possibility of inaccuracy in the determination of the amount of salicylic acid declared by the manufacturer. The process of quality control will ensure that drugs with substandard ingredient are not released into the pharmacies.

Conclusion

The hypothesis tested in this experiment was that the weight of salicylic acid in aspirin manufacture by different companies vary significantly. Indeed the finding of our experiment showed that the hypothesis was correct and hence accepted. Our study reported that the aspirin manufactured by Square carva had considerably high levels of salicylic acid compared to that produced by Ecospirin. The comparison of the methods used in the determination of salicylic acid and other methods used in the previous study revealed that there are improved methods that can be used to enhance the accuracy of the analysis. However, despite the improvements on the methods for determination of salicylic acid, the principle remains the same as the acetone dissolution technique used in our experiment. Both the column chromatography and HPLC methods produced results that supported our findings. The acetone method for determination of salicylic acid in aspirin remains relevant as long as it is applied with caution.

References

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