Hi Poompa,
I have been taking 4.5 mg of naltrexone, LDN, Skip's, for 53 months along with 600 mg of Q10. For about that same time period I have been taking Sinemet and Mirapex. The mix of these two PD drugs has changed but the overall dosage (rather low) has not increased. My PD is early-onset?, tremor based which I've read is slower to progress. I live a normal life and so far, so good.
As Twinkletoes suggested, you should check in with Skips' Pharmacy in Bocca. And you can search this forum for LDN info.

http://skipspharmacy.com/ldn.php

Ashley