Thanks for your query.
Firstly, you have not mentioned the diagnosis of pituitary gland
abnormality (and symptoms/problems encountered by you then) for which you were prescribed Desipramine
The said required information, had it been available, would have enabled me to advise as to how long to take these medicines.
Further, Protriptyline and Trimipramine belong to the SAME class of medicines that you are currently on. So, there will not be any appreciable change in your condition, should you switch over to the new medicines.
You can elaborate your details as advised, through a direct query to me, for medical guidance/advice.
Dr. Rakesh Karanwal