How does dextromethorphan affect the body?

Im talkin about liver, brain, all that, mostly liver though, does it affect the liver

If naltrexone competes for receptors against drugs in the brain then why do they say?

It does not make you feel anything

How pregabalin wokrs?

I understand that Pregabalin works by stopping the pain signals before they reach the brain. Patient will be happy with this drug because he is not feeling pain. What will happen to the already damaged nerve