Thanks for choosing health care magic for posting your query.
The drug you are suggesting could be" mirtzapine". Its belongs to the SNRI
group of antidepressants.
If your father has started speaking faster than usual and has become irritable, they are not the signs of depression
or the side-effect of the drug. Instead it is possible that you father may be having a switch to mania or hypomania
. It suggests that probably your father is having bipolar mood disorder
Do meet your psychiatrist
and discuss these issues. he may want to stop the antidepressant and start him on a different drug.
Hope I am able to answer your concerns.
If you have any further query, I would be glad to help you.
In future if you wish to contact me directly, you can use the below mentioned link:
Wish you good health,
Dr. Srikanth Reddy M.D.