The use of kinetic N-order model in description of active substance release from various drug forms. Part 1. Premises and mathematical analysis of the N-order model.

The paper presents the premises and equations which are the basis of the mathematical n-order model, which contrarily to standard models based on the laws of chemical kinetics, i.e. 0-order and 1-order kinetics, enables categorization of the investigated process taking into account two parameters: the rate at which it occurs, and actual order, which it is distinguished by. Standard models, which assume in advance the kinetic order of the described processes, may be used with satisfactory accuracy to analyze only a low percentage of performed experiments. However, as shown in practice, the order of many physico-chemical processes, including those which are most interesting for us, active substance release from the drug form, may assume intermediate values, what is manifested as various types of "smooth non-linearities" in the obtained release profiles, which cannot be explained on the basis of assumed standard theories. N-order model may be numbered among the group of physical mathematical models based on the premises of chemical kinetics, possessing the analytical structure of internally non-linear function. It is characterized by two parameters: release rate constant K and order coefficient N.