 Patients excluded from the study would include subjects not able to give informed consent,pregnant or breast-feeding women,a current diagnosis of panic disorder, post traumatic stress disorder or psychosis,a history of mania or hypomania,active substance abuse or dependence in the last 6 months, a current depressive episode less than 4 weeks or greater than 12 months in duration, a current or prior adequate trial of lithium or paroxetine,concurrent use of other antidepressants or augmenting agents for the treatment of depression,or a clinically significant medical illness, in particular renal impairment. 