I've given it up... for now. Hubby is not asking for any either.
He took one 50mcg dose last week.

I've had to go back on my SAMe as my right knee has flared up.
Then my shingles pain came back... so it is 1 gram of Lysine a day. With those two, I am doing quite well actually. The SAMe really helps me with mood and dealing with pain. 400mg is what I am using right now daily. I used SAMe for over a decade while I was still working. I thought my knee was fairly normal so I finally discontinued it. So now I think it might be a lifelong thing for me.

The huperzine is difficult. It might be good for some people, but it seems to make me very tense and congests my sinuses, which then leads to pressure headache feelings.

Yes, zorro, that is the one I bought too. They break easily so you can adjust your dose from 25mcg to a full tablet. Keep in mind that it can build up in the body, so you may have to skip days or take "vacation" days from it.

@Breia-- yes, I use DM too. I did notice once when I had a bronchitis, that high dose DM did impact my feet. But now I don't really need that much. I posted here about it in fact.
Keep in mind that using DM is problematic with any antidepressants.

Magnesium is a good NMDA antagonist too. The new Morton Epsom lotion is wonderful rubbing into problematic areas. I use mine every day.

Our PD forum (and also MS) has posts about low dose DM being an agent to prevent neurodegeneration in the central nervous system (CNS). There are many posts about this aspect of it.
If you visit and search those forums, there are lengthy discussions about it. One of our members, Nide44, tried the high dose DM with his doctor's supervision based on some studies that came out several years ago...but it didn't seem to work for him. So I guess it is a highly individualized type of treatment, where some people do well with it, and others don't seem to benefit as much.

I use Robitussin DM at night for excessive sinus congestion or coughing (I used to use an ACE inhibitor which can cause a dry cough)...and did notice that it can help with PN pain. At least it seemed to help with burning when I had that symptom often at night. But I have found over time, that avoiding the nightshade veggies reduced burning for me much more efficiently.