Final answer:
Risperidone (Risperdal) is a possible first line solo antipsychotic IM medication for psychosis. It antagonizes D2 and serotonin type 2 receptors and is commonly used in the treatment of schizophrenia and other psychotic disorders.
Step-by-step explanation:
A possible first line solo antipsychotic IM medication is Risperidone (Risperdal). Risperidone is an antipsychotic drug that antagonizes D2 and serotonin type 2 receptors. It is commonly used in the treatment of psychosis, including schizophrenia and other psychotic disorders.