Right now there are many NMDA receptor modulates in ongoing Phase II FDA studies. Glycine itself since it is a compound that is hard to take (because it requires 20-40 grams of powdered format that must be mixed with water, in studies some people discontinued it because of nausea or vomiting relating to swallowing this amount) and also in the standard studies it must be taken with a conventional antipsychotic. However, there are other NMDA receptor modulates that are specifically targeted to the receptors that are in Phase II FDA study and will be available in standard pill format like all medications and will be able to take as primary (stand alone antipsychotics). Many companies are researching them but Eli Lilly has two promising ones. Here is a standard article on one of them:
http://www.nytimes.com/2007/09/03/business/03drug.html?_r=1
Its not just the side effect profile. In studies they showed an increased beneficial effect on cognitive and negative symptoms, including glycine itself. I am the first to show a further beneficial effect on positive symptoms but as the studies progress they will understand more about this class of antipsychotics in general.
I'm hoping this gets pushed through. I'd love to take a medicine that doesn't have the chance of causing serious side effects like the diabetes or tardive dyskinesia or you know things like significant weight gain and extreme sedation and all that bullsh*t people on antipsychotics have to put up with.