How does methylphenidate interact with nortriptyline?

I have been taking 15mg of Methylphenidate twice each day for the past 18 months. It is for Adult ADHD. I am 59 years old. I have no general history of drug abuse other than having smoke pot and heavy drinking when I was a kid.

From time to time I have taken more Methylphenidate (up to 30mg) per dose and/or taken a third dose during the day. To me it seems 15mg does the job and when I take 20 or 25mg per dose it just gets me a bit reved up. The regular dose of 15mgX2 gives me the "enthusiasm" I need to get through the day.

Just now I started taking Nortriptyline 25mg twice a day for a pinched nerve in my neck. It is supposed to help with nerve pain. I can't say it relieves the pain but it somehow makes it feel different... less intense.

Overall, I am concerned with the combination of the two drugs. One is actually a stimulant, the other an anti-depressant. You'd think they'd work against each other.

I find... after two weeks... that the combination makes me feel quite well as it pertains to ADHD... plenty of focus, no anxiety. Nothing noticed as to adverse side effects.... BP low/normal. Appetite normal.