A Comparative Evaluation Of The Quality Of Generic Telmisartan Tablets With The Brand

Objectives The objective of this study was to comparatively assess the quality of generic Telmisartan tablets manufactured by ten different generic companies against the brand. This was done through comparing the mean telmisartan content in the tablets, number and ratio of impurities in the tablets, solubility of telmisartan used in the tablets and dissolution rate of the tablets.Methods HPLC method was used in the determination of mean Telmisartan content, impurities and solubility of Telmisartan in the tablets and dissolution apparatus II and UV spectrophotometer were used for dissolution tests. Solubility and dissolution tests were carried out in four different media; buffers with pH7.5, pH4.5, pH1.2and water.1. Mean content determination:Tablet powder equivalent to8mg of telmisartan was dissolved in100ml of diluent (0.005N Of Methanolic NaOH), a portion of the solution was filtered and injected into the HPLC, elutes were monitored at298nm.2. Impurities determination:Tablet powder equivalent to8mg was dissolved in8ml; part of the solution was then injected into the HPLC to determine number of impurities. Part of the solution was diluted1000times and injected into the HPLC to determine the percentage of every impurity.3. Solubility tests:Tablet powder equivalent to20mg of telmisartan was dissolved in lml of respective buffer and kept at37℃for48hours then was injected into the HPLC to determine amount of telmisartan dissolved.4. Dissolution tests:The tests were carried out for60minutes; sampling volume was5ml at5,10,15,20,25,30,40,50and60minutes intervals. Six tablets were used in every test and standard telmisartan was used to establish calibration curve in every buffer used. The absorbance was measured at297nm (pH4.5),298nm (pH7.5),296nm (water) and291nm (pH1.2). Results The mean content of telmisartan in all the tablets was within the specified range in the USP. Four generics showed poor solubility and dissolution rate in water, pH7.5and pH4.5with three of them having a relatively huge number of impurities compared to the brand. The other six generics showed more or less the same mean drug content, dissolution rate as that of the brand and a better solubility. Three generics showed to have a comparable number and amount of impurities as that of the brand. The similarity factor disclosed that four generics have a comparable dissolution profiles in two different dissolution media out of the four media used in the dissolution tests.Conclusion1. The telmisartan content of the generic drugs met the criteria but the number and amount of impurities found in some of the generic tablets endanger the safety ofpatients.2. The four generics (generic2,5,9, and10) whose dissolution profiles were not comparable to that of the brand showed poor dissolution rates in the pH4.5, pH7.5and water buffers and high dissolution rate in pH1.2. The same generics showed a poor solubility in all the media with a relatively large number of impurities; two of them having one impurity each which is out of acceptable range. This means that the quality of these four generics is questionable.3. This study showed that while some generics may be of inferior quality to that of their brand counterparts, others can be of approximately the same quality as that of the brand. There is a need for the generic companies to improve their manufacturing practices so that generic and the innovator drug will have a comparable safety and efficacy profiles.