Tricyclic antidepressants may antagonise the blood pressure lowering effects of
clonidine. As
moxonidine is related to clonidine it is expected to interact
similarly.
Tricyclics can also cause postural hypotension, and can cause sedation, both of which could potentially be additive with the effects of
moxonidine.
The manufacturers of
moxonidine advise avoiding tricyclic antidepressants,
because of the lack of
clinical experience of combined use. If the combination is
used, it would be prudent to carefully monitor blood pressure and sedation.