Is It Safe To Take Imipramine For Panic Attacks?

I went to the dr the other day {I don't do often} been having panic attacks what my Dr. from 01 calls them any way I ask the dr to put me back on a low does of xnax which is what has helped in the past I only took them for about six months until I didn't feel like I needed them but this new dr gave me imipram 50 mg to take four times a day why it only adds to my worries and I don't feel like they help what do I need to do