Hypertensive crisis can be a serious side effect, Since this is a contradiction in literature we generally avoid MAOI and TCA combination. Better play safe.
I would rather ask, why you want to combine it? MAOIs are very potent Antidepressant, in adequate dose and duration, i think will be sufficient for your patient. I also hold the same opinion like others who opined , better to avoid adventurous practice rather play safe.
In my view, combining Nortripiline and MAOI is not a wise decision, as these medications are outdated and can be difficult to tolerate. Additionally, their combination is not considered to be safe. A better option might be to try the combination of venlafaxine and mirtazapine, which is believed to enhance the antidepressive effects. This combination is considered to be more effective and easier to tolerate compared to the combination of Nortripiline and MAOI.
With a lower dose od Nortriptylin it should be fine. Especially if the patient runs for a longer time with 25mg N.evenings and didn't tolerate other AD (like on of my patients), I wouldn't stop just because of MAOI. Higher dose of TCA together with MAOI neither make sense, as already mentioned here, nor are to recommend for safety reasons. Generally, considering MAOI, I think sometimes we worry to much about the side effects. In the clinical praxis, they are much safer than reputation suggest ;)
Much like many of the previous writers, I would avoid this combination of medications. There are many other options for augmentation if needed such as lithium, pramipexole, Second or third generation antipsychotics, liiothyronin, ...