Agmatine and memantine--risks of combining?

Vermont, school in Western MA
I use both agmatine and memantine to keep opioid tolerance reasonable or low. And to prevent hyperalgesia. (I also use ultra low dose naltrexone at the same time but I dont think that has any interactions) Memantine has fairly well documented mechanism of action and side effects and human trials but agmatine doesnt.

It seems like agmatine works well in rats to lower opioid tolerance and hyperalgesia and also it may lower blood pressure via affecting nitric oxide Pathways, but its still not clear what its ultimate mechanism of action is--nmda antagonist, or something else?

Anyway, memantine is a straightforward NMDA antagonist with not that many risks but it can cause hypertension or stroke in rare cases. Agmatine usually lowers blood pressure, not raises it. If I was just going by what we know for sure , I wouldn't say this is a risky combination. But it's possible that there are mechanisms of action with agmatine that make this a risky combination.

I'm going to ask the doctor who prescribed the memantine , but it may take awhile to hear back so im curious about this in the meantime

Any thoughts? If anyone knows anyone who is using these supplements and drugs please tag them as I would like their opinion. @Hip do you know anyone using either of these meds?

Also does memantine pose any risks with POTS, constipation or heart issues on it's own? Curious