Trazodone Conventional and Controlled-Release Formulations: Pharmacodynamic Effects After Single and Repeated Administration

Summary In a double-blind study, the pharmacodynamic effects of single and repeated doses of two formulations of trazodone were compared in 14 healthy young volunteers (6 men and 8 women). They received either 100 mg trazodone conventional capsules or 150 mg controlled-release tablets daily at 08.00 hours for two 7-day periods separated by a ‘wash-out’ period of 2 weeks. Blood pressure standing and lying, critical flicker fusion frequency and manual dexterity were measured on Days 1 and 7 of each session before and at intervals up to 8 hours after the dose. Manual dexterity was tested by measuring the time taken to drop 50 airgun pellets down a narrow tube. A daily pre-dose blood sample was also taken for measurement of trazodone to check compliance and to confirm that steady state had been achieved. Steady state plasma concentrations were reached by Day 2 of repeated dosing on both treatments. There was a trend towards shorter duration of the expected depressant effect of trazodone on critical flicker fusion frequency and manual dexterity on Day 7 for both treatments, which was significantly different between treatments for manual dexterity (p