Final answer:
Immediate medical treatment for a schizophrenic patient overdosing on antipsychotics includes hospitalization to monitor vital signs and manage extrapyramidal symptoms with anticholinergic medications. Urinary retention may be treated with cholinergic drugs or catheterization.
Step-by-step explanation:
If a patient with schizophrenia has overdosed on antipsychotics, resulting in extrapyramidal symptoms (EPS) and urinary retention, immediate medical treatment is required. EPS are drug-induced movement disorders, which include symptoms such as tremor, rigidity, bradykinesia, and tardive dyskinesia. These symptoms are similar to those seen in Parkinson's disease, which are thought to arise due to the blockade of dopamine receptors by antipsychotics, leading to decreased dopamine neurotransmission.
Treatment for EPS may involve the use of anticholinergic medications, such as benztropine or diphenhydramine, to counteract the effects of dopamine receptor blockade. As for the urinary retention, this can be a side effect of antipsychotic medications, and the treatment might include cholinergic drugs to stimulate bladder contraction or temporary catheterization, if necessary. All cases of overdose require hospitalization and supportive care, where vital signs are monitored, fluids are administered, and, if warranted, medications to address specific symptoms are given.