Almost all the life, before trying NMDA antagonists, I had tremedous tolerance to benzos, and never felt any anxiolysis from any doses. I was taking 6-8 mg of clonazepam, >1 mg of triazolam, 20-30 mg of oral midazolam, 4 mg of flunitrazepam and equivalent dosages of almost all available benzos, and have felt some action only on >30 mg oral midazolam and at about the same amount of zolpidem (non-benzo). Now I can feel as low as 0.25 mg of clonazepam.
Can you give some more information on what pattern of NDMA antagonist use led to this? Was it a sudden transition from not being able to feel benzos or a gradual one? What NMDA blockers were you using, for how long, in what combinations, and what was your pattern of benzo use during the time that you used NMDA blockers? What other GABA or glutamate modulating drugs were you using, if any (eg, GHB/GBL/butanediol, phenibut, baclofen, barbiturates, AMPAkines or other nootropics, alcohol)?
I used to experience huge euphoria from benzos and compulsively took very large amounts, like 1g diazepam and 30-90mg alprazolam a month - well, in more of a 2 week period, followed by about 2 weeks on GBL and then back onto benzos - I used one drug to withdraw from the other. I didn't notice tolerance building to the benzo euphoria. At one point, after a few months of this, I was using GBL while having a pretty bad benzo withdrawal. I found 20mg valium and one or 2 1mg xanax. They all gave me the customary euphoria I was used to.
Then, a week or two later I got a new batch of benzos. I got no euphoria from them at all. Even taking large amounts I would feel sober. I thought I had been ripped off, but eventually I learned that I had developed a permanent tolerance to benzos. That was at the end of 2008. To this day, even when I have had periods of years without using benzos, they still would not give me pleasure like they used to. The only time I have enjoyed benzos since then was once, taking valium during my final GBL withdrawal in late 2009, and another time, for maybe 40 mins, when I had missed a daily methadone dose and, in slight withdrawal, taken a couple of xanax - I felt a slight reminder of how they used to make me feel, but it faded quickly. All benzos do to me now is make me less self conscious, less inhibited, and mess up my memory. I can still get anxious and depressed and there is no euphoria or physical pleasure like I used to get.