Relative bioavailability studies on a locally manufactured aspirin tablets using UV Spectrophotometry and HPLC

Thumbnail Image
Journal Title
Journal ISSN
Volume Title
Modern trends in drug analysis require use of less time consuming, efficient. Cost effective, fast, reproducible, simple and convenient methods. Two analytical methods were employed for the determination, the UV spectrophotometry and the HPLC. Aspirin, which is rapidly deacetylated to salicylic acid after absorption into the plasma, is excreted in the urine. In determining the salicylic acid concentration in the urine, the absorbance was quantitated by a spectrometer at a wavelength of 540nm. Aspirin formed an amber coloured complex with ferric ions (Trinder’s reagent). The complex, which formed instantaneously at room temperature, was stable. The solution of the complex obeyed Beer’s law at 540nm, the wavelength of maximum absorption of radiation (λmax). Phenol—induced absorbance is quenched by acidifying the reaction mixture with phosphoric acid. An HPLC analytical method was used in determining the free salicylate excreted in the urine. The mobile phase employed is a validated method from the USP- XXII (1990) which consists of water, methanol and glacial acetic acid in the ratio 69: 28: 3 respectively. The chromatographic conditions involved a flow rate of 1 .Oml/rnin, wavelength of maximum absorption of 236nrn, stationary phase Spherisorb S5 ODS 1 phase sep column with standard dimensions of 25.0cm length and 4.6cm diameter. and chart recorder speed of 5mm/min. The quality of the reference and the test tablets were assessed by a number of standard tests, which include uniformity of weight, friability, hardness and dissolution that fall within the BP 2000 specification. The observation from the study reveals that the relative bioavailability of aspirin (w.r.t. salicylic acid) were 103.39% and 94.93% for HPLC and UV respectively. The mean cumulative percentage of the drug excreted in both cases were ii .05% and 10.69% for test and reference respectively for HPLC and 76.45% and 80.53% for test and reference respectively for UV analysis. The cumulative amount of aspirin excreted (w.r.t. salicylic acid) were analyzed statistically in other to establish whether there is any significant differences between the standard deviations and the mean amount of drug excreted at 95% confidence level. There was no significant difference in both cases.
A thesis submitted to the Department of Pharmaceutical chemistry, Faculty of Pharmacy, College of Health Sciences in fulfilment of the requirements for the degree of Master of Science in Pharmaceutical analysis and Quality Control, 2005