Single and multi-dose kinetics of zimelidine have been evaluated along with changes in biochemical and cognitive measures. Kinetic evaluation in 4 elderly patients with dementia (Alzheimer's type) indicates that linearity in the system is maintained over low doses achieving lower steady-state plasma concentration of zimelidine, however, higher doses tend to saturate the drug metabolic pathways resulting in a non-linear system. The predicted level of Nor-zimelidine (an active metabolite) following oral dosing of zimelidine showed poor correlation with the observed concentrations. Kinetics of both zimelidine and its metabolite were similar to those previously reported in other subpopulations. Drug accumulation and the associated toxicity, not at all significant in this study, have been reported previously leading to the discontinuation of the drug by the manufacturer.