Comparative In Vitro Quality Evaluation of Different Brands of Ibuprofen Tablets Marketed in Mekelle, Ethiopia

Objective: Quality of pharmaceutical products is required to guarantee their safety and e�cacy. The aim of this study was to evaluate the physicochemical quality attributes of different brands of ibuprofen tablets marketed in Mekelle, Ethiopia. The methods stated in the British Pharmacopeia were adopted for weight uniformity, hardness, friability, disintegration test and assay of drug content. Dissolution test was also carried out as stated in the United States Pharmacopeia. To compare dissolution pro�le, statistical analysis of drug release at different time points were employed. Results: All the brands were found with acceptable pharmacopeial speci�cations for weight uniformity, friability, hardness, assay of drug content and dissolution test. Six brands ful�lled the pharmacopeial requirements of disintegration test while one brand failed to disintegrate as per the BP speci�cation. However, there were statistically signi�cant difference in weight, hardness, disintegration, dissolution and amount of drug content among the tested samples. Thus, from this study we can conclude that all the products ful�lled the required quality evaluation parameters as stipulated in pharmacopeias except one brand which failed the disintegration test. However, the in vitro dissolution pro�le indicated that there may be a potential bio-in equivalence among the pharmaceutical products.


Introduction
Generic medicine is a pharmaceutical product that can be interchangeable with the innovator medicine.
Generic medicine is the same as its corresponding innovator medicine in terms of quality, safety, e cacy, strength, dosage form, route of administration and intended use [1][2][3].However, there are misperceptions that generic medicines are less effective than branded drugs and/or generic drugs are poor quality as compared to brand medicines by health care providers and patients [4].
There are many pharmaceutical companies and distribution channels of drugs worldwide.Unfortunately, circulation of poor quality drug products in the international market increase signi cantly as a result of ineffective regulation of manufacturing and trading of pharmaceutical products [5].Therefore, the manufacturing, distribution, storage and use of drugs need to be regulated authorized regulatory institutions [6].
Poor quality medicines are public health problems that affect both developing and developed countries [7,8].According to the World Health Organization, in low and middle-income countries 10% of the medical products are either substandard or falsi ed [9].Since, Ethiopia is one of the low-income countries, falsi ed or substandard medicines could be available in the market.These could be due to lack of adequate resources, weak regulatory enforcement, weak port control, lack of informal market control, poor cooperation between executive bodies and resource constraint [6,10].Poor quality drug products could cause treatment failure, increased mortality and morbidity, drug resistance and economic loss [11].
Ibuprofen is one of the commonly used generic none steroidal anti-in ammatory drug in the world.It has analgesic, anti-in ammatory and anti-pyretic activities [12].The main purpose of this study was therefore to evaluate the quality of different brands of ibuprofen products available in drug retail outlets in Mekelle, Ethiopia.

Materials
Reference standard of ibuprofen was obtained from Addis Pharmaceutical Factory and seven brands of 400 mg lm coated ibuprofen tablets were randomly purchased from different pharmacies and drug stores in Mekelle.

Methods
Weight uniformity, hardness, friability, disintegration, dissolution and assay of drug content were performed based on speci cations stipulated in the British Pharmacopeia (BP) and the United State Pharmacopeia (USP).

Weight uniformity
From each brand, twenty tablets were randomly selected, weighed individually and then average weight was determined.Then percentage deviation of individual weight from average weight was calculated [13].

Hardness
The crushing strength of the tablets was determined by selecting randomly ten tablets from each brand and measuring their hardness by using a hardness tester apparatus [13].

Friability
Twenty tablets from each brand were weighed using an analytical balance.These tablets were placed in the drum of the friability tester and subjected to rotation at 25 revolutions per minute (rpm) for 4 minutes.The tablets were removed from the apparatus and weighed again.Percent friability was calculated for each drug product [13].

Disintegration
Disintegration of the products was determined in 900 mL of distilled water as stipulated in the BP.The temperature of the medium was maintained at 37 ± 2 o C. One tablet was placed in each of the six tubes, then the basket rack assembly started to move up and down.The tablets were considered disintegrated when all of the particles pass through the mesh screen.If any residue remains, it must be fragments of insoluble coating.The time in minutes required to disintegrate for each tablet was recorded and average disintegration time for each product was calculated [13].

Dissolution
A calibration curve (Figure 1) was constructed using ibuprofen reference standard to evaluate the drug release of the products.Ten mg of standard ibuprofen was dissolved in a 100 mL volumetric ask using a phosphate buffer pH 7.2.After gentle shaking, the volume was made up to 100 mL using the same solvent and that solution was used as the stock solution.From this solution, concentrations corresponding to 1, 2, 4, 6, 8 and 10 μg/mL were prepared.After ltration, the absorbance of the ltrate was measured at a wavelength of 221 nm using UV/VIS spectrophotometer.The buffer was used as a blank.Then, a calibration curve of absorbance against its corresponding concentration was constructed [14].
Dissolution test of ibuprofen tablets was employed by using USP apparatus II (paddle method) [15].For each brand, in each of the six vessels, phosphate buffer (900 mL, pH 7.2) at 37 ± 0.5 o C was used as a dissolution medium.The rotation of the paddle was set at 50 rpm.Filtered sample solutions (10 mL) were withdrawn at 10, 20, 30, 45, 60, 75 and 90 minutes.After appropriate dilution the absorbance of was measured by UV/VIS spectrophotometer at 221 nm.The dissolution medium was used as a blank.The concentration of drug released at each time point was determined using the calibration curve.Dissolution pro le among the products of ibuprofen tablets were carried out by statistical analysis of drug release at different time points [16].

Assay of active ingredient
A mobile phase was prepared with orthophosphoric acid, distilled water and methanol (3:247:750, v/v/v).
Standard ibuprofen solution was prepared with a concentration of 2 mg/mL.The solution was ltered by 0.45 μm membrane lter then injected into the HPLC system.The analysis was performed using shodex C 18 column (25 cm × 4.6 mm, 5 µm) at a temperature of 30 o C, ow rate of 0.75 mL/min and injection volume of 20 μL.Detection was performed at 264 nm [13].
Sample solution was prepared using twenty tablets from each brand then weighed and powdered by mortar and pestle.A powdered sample equivalent to 0.2 g of ibuprofen was dissolved in 30 mL of mobile phase and then diluted to volume (100 mL).From this solution, 25 mL was taken and centrifuged at 2500 rpm for 5 minutes.Filtered supernatant sample solution was analyzed by using HPLC system as described above for the reference standard.

Weight uniformity
Weight variation of the tablets indicates variation in amount of active ingredient (API) and/or excipient (s).Variation in amount of API may lead to toxicity, ineffectiveness or unpredictable action of the drug products.Variation in amount of excipient/s may also affect other physicochemical characteristics of the product and ultimately it may alter the bioavailability and therapeutic activity of the drug [13,17].Therefore, weight variation among unit dosage forms should be within narrow range.The results (Table 1) indicated that weight uniformity of the brands was within the acceptable limit as stated in the BP speci cations [13].There exists statistically signi cant difference among the brands mean weight (p<0.0001).This could be due to the fact that manufacturers may use different amounts of additives and/or API in varying proportion for the drug products.

Hardness
Tablet hardness is the measure of the force required to break tablets in diametric compression [18].It should not be so low that the tablets are soft and may not be able to withstand conditions of storage, handling and transportation without breaking.Conversely, tablets should not be too hard because they may not disintegrate in the required period of time and it may affect the dissolution and bioavailability of the drug product.Hardness is one of the quality evaluation parameter of tablet dosage forms-and should be above 40 Newton [19].All of the examined products (Table 1) complied with the speci cations.
There was a signi cant difference in their mean hardness (p<0.0001)among the different brands of ibuprofen tablets.Manufacturers may use different method of production including a difference in the method of granulation, compression force and excipients resulting in variation of tablet hardness [20].

Friability
Friability (F) was conducted to evaluate the ability of tablets to withstand abrasion to packaging, handling and transporting [21].If tablets are less friable, they will maintain good appearance without becoming dusty during storage, transporting or dispensing.On the other hand, if tablets are highly friable, patient acceptability of the medicine may decrease and the patient may get under dose because of abrasion of the tablets then ultimately treatment failure may occur.According to the BP, if the %F of tablet is not greater than 1%, the test complies [13].As shown in Table 1, the %F was found in the range of 0.01 -0.04%.

Disintegration
According to the BP speci cation, lm-coated tablets should be disintegrated within 30 minutes [13].All of the samples disintegrated within the acceptable tolerance limit of lm-coated tablets except IBU-E which disintegrated after 39.1 minutes (Table 1).A one-way analysis of variance (ANOVA), showed that there was a signi cant difference (p<0.0001) in mean disintegration time among the different products of ibuprofen tablets.

Dissolution
Dissolution of tablet dosage form is related to the absorption and bioavailability of drugs [18].Results indicate that all of the studied ibuprofen tablets released more than 80% within 60 minutes (Figure 2) and hence ful lled the o cial dissolution requirements as stipulated in the compendia [15].Drug product IBU-C had the highest percentage of drug release (98.45%) while IBU-E was the least with percentage drug release of 87.67% at 60 minutes.
The availability of various brands of medicines (e.g.ibuprofen) put health care professionals and patients into confusion about which brand to choose and the possibility of interchangeability among the brands [22].In order to ensure interchangeably, bioequivalence study is required.To verify this, a similarity in rate and extent to which the drug in the dosage form become available for absorption need to be investigated.In vitro bioequivalence study among different products can be carried out using different methods.In cases when greater than 85% of the drug is dissolved within 15 minutes, dissolution pro les are usually considered as similar without further evaluation [23].However, all of the products dissolution rates did not meet 85% dissolution within 15 minutes and were subjected for further statistical evaluation to demonstrate bioequivalence.A one-way ANOVA indicated that the brands had statistically signi cant difference (p<0.0001) in mean drug release at the tested time points (10, 30, 60 and 90 minutes).This could be due difference among manufacturers in the method of production such as use of different excipients (amount and type) and varying amount of API [22].The results have shown that continuous quality evaluation of the multisource drug products is required for rational decision making regarding their quality and interchangeability.The difference in dissolution rate among the different brands might in uence the drug products effectiveness and side effect.

Assay of active ingredient
Tables Table 1: Results of weight, hardness, friability and disintegration time and drug content of seven brands of ibuprofen tablets (13,15,19 ).