Diffusion coefficient of paracetamol in a chitosan hydrogel

The diffusion coefficient of the analgesic drug paracetamol (acetaminophen) in macroporous chitosan hydrogels has been measured using a diaphragm cell technique. The pore structure in the hydrogel was varied by changing the amount of chitosan added to the aqueous solution. At 37 C, the measured values of the diffusion coefficient are between 0.1 and 5 x 10(-8) m(2)/s depending on the macropore size in the hydrogel. The diffusivity increases with temperature and the activation energy has been estimated to be on the order of 25 to 30 kJ/mole. The data indicate that solute transport through the gel occurs primarily by Fickian diffusion. (C) 2004 Elsevier B.V. All rights reserved.