Awesome. Can't wait until these new treatments for schizophrenia/schizoaffective disorder get FDA approved that you write about. Let's get some safer treatments out there as an option. Is this the very first possible adjunct for schizophrenia? What type of medicine is it?
Zofran is a serotonin 5-HT3 receptor antagonist. Zofran reduces the activity of the vagus nerve, which activates the vomiting center in the medulla oblongata, and also blocks serotonin receptors in the chemoreceptor trigger zone. It has little effect on vomiting caused by motion sickness, and does not have any effect on dopamine receptors or muscarinic receptors.
A 2006 double-blind, randomized controlled trial indicated that ondansetron may have value in the treatment of schizophrenia, as an adjunct to haloperidol. The study found the combination to significantly improve negative schizophrenia symptoms, and people taking both drugs experienced fewer of the adverse effects commonly associated with haloperidol; an earlier, smaller, open-label trial had found ondansetron to be useful in treating antipsychotic-induced tardive dyskinesia in people with schizophrenia, and the study patients also showed significant improvement in the disease's symptoms.
Okay I'll explain (from my knowledge as a consumer) what that information I cut and pasted means. Zofran is FDA approved for use in nausea from chemotherapy. All other uses are experimental. The 5-HT3 receptors are one group of neurotransmitters they are studying that may work as part of schizophrenia. There are other receptors and treatment modalities they are studying as adjuncts as well. This is the only one that is in use outside of clinical study (as an FDA approved medication can be used off label at a doctor or psychiatrist's discretion). However its specific use is as adjunct for schizophrenia. It is also used as adjunct in clinical study for tardive dyskinesia, Parkinson's Disease and psychosis from Parkinson's (which is different in origin than schizophrenia psychosis, they also found it of use in me in the study criteria tardive psychosis but more research needs to be done on that criteria itself before its determined whether it exists or not to begin with).
As per the receptors mentioned, dopamine receptors are of course the standard receptors that antipsychotics work on. Muscarinic receptors are ones that current antipsychotics (and other medications) effect but not purposely. They are the reason that antipsychotics (and other medications that effect these receptors) cause weight gain. I was allowed to use Zofran for tardive dyskinesia and although it was effective it does have a heavy side effect profile and I personally could not tolerate it but each person responds differently to each medication. More of importance this class of receptors are being studied in general and antipsychotics being developed that work on them as well as antipsychotics that work on them in addition to other receptors. This class of antipsychotics works on cognitive and negative symptoms so it will either augment a conventional antipsychotic or be part of an antipsychotic that effects multiple receptors. How these receptors work in schizophrenia is in clinical study itself.