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AN ATLAS OF SCHIZOPHRENIA - PART 8

Một đại diện của các mối quan hệ thụ thể tuyệt đối của haloperidol so với Một số các thuốc chống loạn thần mới hơn 'không điển hình, rút ra từ dữ liệu trong tài liệu tham khảo 112. Mỗi dòng đại diện tại thụ thể duy nhất, thêm Cùng dòng thanh là The Higher Do ái lực của thuốc đối với thụ thể đó đó. | Figure 4.17 A representation of the absolute receptor affinity of haloperidol in comparison with some of the newer atypical antipsychotics drawn from data in reference 112. Each line represents a single receptor the further along the bar on a given line the higher the affinity of that medication for that receptor. Each of the gradations on the lines represents 10 times greater affinity for that receptor. What can be seen from this is that clozapine quetiapine and to a lesser extent olanzapine have much lower affinities for the dopamine D2 receptor than haloperidol. This may be why they are atypical in terms of producing fewer extrapyrimidal side-effects than antipsychotics such as haloperidol. Risperidone and ziprasidone have similar D2 receptor affinities to haloperidol and yet they too are atypical . It has been hypothesized that very high affinity for the serotonin-2A receptor 5-HT2A may underlie the atypicality of ziprasidone and risperidone. Indeed this may be important for atypicality per se as all of the newer medications have a higher affinity for the 5-HT2A than for the D2 receptor. Amisulpride by contrast to the medications in this figure only has appreciable affinity for D2 and D3 receptors and has high equipotent affinity for both receptors as can be seen in Table 4.3. Data from reference 45 2002 CRC Press LLC CLOZAPINE vs. CHLORPROMAZINE IN TREATMENT-RESISTANT SCHIZOPHRENIA Clozapine Chlorpromazine Figure 4.18 Comparison of efficacy of clozapine versus chlorpromazine in treatment-resistant schizophrenia. Figure reproduced with permission from Kane J Honigfeld G Singer J Meltzer H. Clozapine for the treatment-resistant schizophrenic a double blind comparison with chlorpromazine. Arch Gen Psychiatry 1988 45 789-96 receptors. It is postulated that it is the balance between the blockade of these receptors that underlies clozapine s clinical efficacy in improving positive and negative symptomatology. Clozapine is an antagonist at the 1 receptor but less so