An Investigation of the Potential Interaction between Paroxetine and Pindolol : Pharmacodynamic Assessment in Healthy Male Volunteers

The increasing incidence of cardiovascular disease and subsequent depressive symptoms has highlighted the potential for concomitant treatment of β-blockers and antidepressant medication. It has been noted that both types of medications are associated with decrements in psychomotor and cognitive performance. Thus, the aims of this study were to characterise the psychomotor performance characteristics in a group of healthy male volunteers who received a single oral dose of paroxetine 10 mg (an SSRI), pindolol 5 mg (a β-blocker), a placebo and a combination of paroxetine and pindolol. It was hypothesised that concurrent administration of single doses of paroxetine and pindolol will result in a significant decrease in psychomotor performance. The study was conducted as a double blind, placebo controlled, four-way cross over study. To assess the psychomotor effects of the administered drugs, the participants were required to perform the critical flicker fusion frequency task (CFF), choice reaction time task (CRT), BondLader visual analogue scale of mood (VASM) and the digit-symbol substitution test (DSST). A significant effect between condition and time for CRT (F(3)= 7.918, p<0.001), CFF (F(3)= 2.459, p<0.05), and DSST(F(3)= 2.488, p<0.05) tests was found, which indicated that a decrement in psychomotor performance over time had occurred after concurrent administration of paroxetine and pindolol together. The explanation for the drug-drug interaction is not clear from this study, but may be due to one or more factors, such as a pharmacokinetic or pharmacodynamic interaction.