ACP-104 or N-Desmethylclozapine (NDMC), or norclozapine is a major metabolite of clozapine, which was developed like a small molecule drug candidate by ACADIA for treatment schizophrenia. ACP-104 combines M1 muscarinic agonist, 5-HT2A inverse agonist, and D2 and D3 dopamine partial agonist in a single compound and, therefore, uniquely addresses what ACADIA believed are the three most promising target mechanisms for treating schizophrenia. Then drug was discontinued, because the study did not meet its primary endpoint of antipsychotic efficacy or any of the secondary endpoints. Neither dose of ACP-104 demonstrated improved efficacy as compared to placebo. The most common adverse events in the treatment arms relative to placebo were increased salivation, tachycardia, and dyspepsia, which were noted to be dose-related. There was no clinically significant decrease in neutrophil counts in the study drug arms.