For the modelling of the kinetics of diffusion and relaxation in the polymer matrix, the power law equation in a two-parameter oř three-parameter form is employed. The introductory part of the páper summarizes the emplo-yed varieties of the power law equation including the equation making it possible to distinguish diffusion from relaxation. The liberation kinetics of pilocarpinium chloride from lyophilized lamellae with graded amounts of hydroxypropylmethylcellulose is expressed by power law equations and their parameters are compared. The conclusion discusses the usability of the power law equation in the modelling of liberation of active ingredients and recommends the use of the three-parameter power law equation with a shift of the liberation out of the ori-gin of the coordinates

        Key words: power law equation - liberation kinetics - pilocarpinium chloride - hydroxypropylmethylcellulose