Nortriptyline is a straight noradrenaline/norepinephrine reuptake inhibitor. It has little impact on serotonin. Imipramine is a fairly potent serotonin and mild noradrenaline reuptake inhibitor, and clomipramine is both a very potent serotonin and noradrenaline reuptake inhibitor.
Perhaps as you're going from a med with very little serotonin activity to a very potent serotonin reuptake inhibitor. However, the TCAs tend to produce less severe side-effects at the beginning than SSRIs/SNRIs, although, as with everything about antidepressants, there are no guarantees.Also when swapping over, is there likely to be a lot of side effects, given they are from the same class of meds.
TCAs are not a uniform group of meds which all do basically the same thing as is the case with SSRIs. Their effects differ greatly in how they work.
Not necessarily as they do different things.Also if Nortriptyline didn't work, is it likely that swapping to Imipramine won't do much good either? My main complaints are high anxiety and depression.