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genetic predispositions and prenatal insults result in aberrant brain development involving prefrontal and temporolimbic areas. The functional activity of these regions and neurotransmitter systems are altered, resulting in the symptomatology of schizophrenia.

Whatever the underlying causes may be, neuroleptic medications are the most effective treatment for schizophrenia. All antipsychotic medications have some form of dopamine receptor antagonism and they are distinguished by their chemical class. The phenothiazines include chlorpromazine (Thorazine), thioridazine (Mellaril), mesoridazine (Serentil), trifluoperazine (Stelazine), fluphenazine (Prolixin), and prochlorperazine (Compazine). The thioxanthenes include chlorprohixine (Taractan) and thiothixene (Navane). Butyrophenones are represented by haloperidol (Haldol). Loxapine (Loxitane) is a dibenzoxapine, and molindone (Moban) is a dihydroindolone. A newer generation of antipsychotics have been introduced in the 1990s that have the dual advantages of reduced extrapyramidal effects and amelioration of negative symptoms. These drugs include clozapine (Clozaril), risperidone (Risperidal), and olanzepine (Zyprexa). Pharmacologically, they antagonize 5-HT2A receptors as well as dopamine receptors. Sertindole (Serlect) is yet another new generation antipsychotic that has a variety of dopamine and serotonin antagonist effects. With the discovery of dopamine receptors beyond the D1/D2 dichotomy, many antipsychotics were found to have effects there too. For example, clozapine has less efficacy at the D2 receptor, but stronger effects at D4 receptors. Haloperidol is an antagonist at D3 as well as D2 receptors. Side Effects

Antipsychotic drugs vary according to their side-effect profiles regarding sedation, autonomic effects, and extrapyramidal motor symptoms. Sedation and autonomic effects are mediated, in part, by the muscarinic cholinergic and alpha adrenergic effects of the drugs. While the binding to D2 receptors predicts dosage and efficacy for antipsychotic drugs, it also predicts extrapyramidal motor symptoms (Seeman 1987). These include akathisia (or motor restlesness), dystonic postures, and parkinsonism (resting tremor, bradykinesia, and limb rigidity). Due to the functional relationship between dopamine and acetylcholine in the basal

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