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<< JRScience Home   Volume 13 No.1 June 2002  << Back to Volume Home




N.M. Ranjha1, Rahat Ramzan1, Naveed Aslam1 and Wilayat Ahmad2

1Department of Pharmacy, Bahauddin Zakariya University, Multan, 2Department of Pharmacy, Gomal University, Dera Ismail Khan, Pakistan.


The dissolution behavior of five commercially available brands of enteric coated aspirin tablets were studied, both in 0.1N HCl adjusted to pH 1.2 and phosphate buffer solutions of pH 4.0, 5.0, 5.5, 6.5, 7.0 and 7.5 using USP dissolution apparatus II (paddle method). The drug concentration in dissolution media was determined spectrophotometrically at respective lmax i.e. 276 nm for pH 1.2 and 4.0, 268 nm for pH 5.0 and 5.5 and 266 nm for pH 6.5, 7.0 and 7.5 solutions and the data were analyzed by cube root law. Study has revealed that dissolution rate increases with increase in pH of dissolution medium. At intestinal pH Loprin and Anaprin have fastest disintegration and dissolution followed by Ascard and Anaprin. Nu-Seals failed to release appreciable quantity of drug even at intestinal pH. It has been suggested that possible reasons for difference in dissolution behavior are the difference in the film coating material, techniques and the quantity of hydrophobic excepients employed by different manufactures, which retard penetration of dissolution medium and ultimately decrease availability of drug in the solution.


Keywords: Aspirin, dissolution, enteric coating, hydrophobic excepients, tablets.