Pharmacokinetics and pharmacodynamics of scopolamine after subcutaneous administration

The effects of subcutaneously administered scopolamine on quantitative electroencephalogram (qEEG) and cognitive performance were evaluated and correlated with pharmacokinetic parameters in a randomized, double-blind placebo-controlled crossover study of 10 healthy male volunteers. Changes in qEEG and cognition were determined for 8 hours after drug administration. Scopolamine produced dose- and time-dependent impairments of attention and memory and a time-dependent increase in delta power (1.25-4.50 Hz) and a decrease in fast alpha power (9.75-12.50 Hz) on qEEG compared with placebo. Maximum serum concentrations of scopolamine occurred 10 to 30 minutes after drug administration. Mean peak serum concentrations (free base) were 3.27, 8.99, and 18.81 ng/mL after administration of 0.4, 0.6 mg, and 0.8 mg scopolamine, respectively. Elimination half-life was approximately 220 minutes. The findings indicate temporary changes in qEEG and psychometric tests, and support the possible use of such a testing model for impaired cognitive functions such as age-related memory disturbances.