In antipsychotic drug action

Meltzer HY (1999) The role of serotonin in antipsychotic drug action. Neuropsychopharmacology 21 106S—115S... 

Schwartz, J.-C., Diaz, J., Pilon, C., and Sokoloff, P. (2000) Possible implications of the dopamine D3 receptor in schizophrenia and in antipsychotic drug actions. Brain Res Rev 31 277-287. 

Snyder, S. H., 8c Largent, B. L. (1989). Receptor mechanisms in antipsychotic drug action Focus on sigma receptors. Journal of Neuropsychiatry, 1, 7-15. 

Due to the importance of dopaminergic signalling in TD development, and the suspected role of the dopamine D3 receptor (DRD3) in antipsychotic drug action, at least 20 studies have investigated... 

D receptors are unlikely to play a pivotal role in antipsychotic drug actions, perhaps because their avid affinity for endogenous DA prevents their interaction with antipsychotics. The subtle and atypical functional activities of cerebral D receptors suggest that D agonists rather than antagonists may have useful psychotropic effects, particularly in antagonizing stimulant-reward... 

FIGURE 11 — 2. The dopamine receptor antagonist hypothesis of antipsychotic drug action for positive symptoms of psychosis in the mesolimbic dopamine pathway is shown here. Blockade of postsynaptic dopamine 2 receptors by a dopamine 2 antagonist acting in the mesolimbic dopamine pathway is hypothesized to mediate the antipsychotic efficacy of the antipsychotic drugs and their ability to diminish or block positive symptoms. 

While EPS and catalepsy in experimental animals are no longer considered to be necessary consequences of antipsychotic drug action (224,225), even the newest atypical antipsy-chotics block Dg receptors to varying degrees (12,13), and with the exception of quetiapine, can induce EPS, catalepsy, and increase serum prolactin at high doses (226-228). Thus, tests for such liabilities remain in most antipsychotic screening batteries. 

If sedatives, barbiturates, antipsychotic drugs, stimulants, opiates and thyroid medications all outperform inert placebos in the treatment of depression, does this mean that any active drug can function as an antidepressant Apparently not. In September 1998 the pharmaceutical company Merck announced the discovery of a novel antidepressant with a completely different mode of action than other medications for depression. This new drug, which they later marketed under the trade name Emend for the prevention of nausea and vomiting due to chemotherapy, seemed to show considerable promise as an antidepressant in... 

Meltzer HY. Role of serotonin in the action of atypical antipsychotic drugs. Clin Neurosci 1995 3(2) 64—75. 

The answer is c. (Hardman, pp 574—575.) Phencyclidine is a hallucinogenic compound with no opioid activity Its mechanism of action is amphetamine-like. A withdrawal syndrome has not been described for this drug in human subjects. In overdose, the treatment of choice for the psychotic activity is the antipsychotic drug haloperidol. 

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