Wouldn't "memantine" be effective for social anxiety? I say this because Dextromethorphan which is cough medicine has been quite effective in helping my anxiety and ADD and I've seen many anecdotal reports online of people self medicating with it. There's a theory about overactive glutamate receptors and how NMDA antagonists can help.. I remember using DXM for a job interview.
Es-Ketamine is one of them but the treatments are only approved for depression and is expensive.