Developments in antipsychotic therapy with regard to hypotheses for schizophrenia

The typical antipsychotic drugs like chlorpromazine and haloperidol were discovered by serendipity in the 1950s. A number of so-called “me too” drugs with similar chemical structures and modes of action were marketed in the subsequent years. The first atypical antipsychotic, clozapine, was an exception because it lacked some of the pharmacological properties of the typical antipsychotics related to the extrapyrimidal motor system. This unique feature of clozapine significantly broadened understanding of the mode of action of antipsychotics, and created new hypotheses for schizophrenia. Hypothesis-orientated development of new drugs was only recently initiated. Abnormalities of the immune system in schizophrenia are being increasingly discussed: shifts in the levels of T helper cells subsets 1 and 2 (Th1 and Th2) have been observed, and studies with risperidone and the cyclooxengenase (COX2) inhibitor celecoxib as an add-on therapy have provided very promising results. The glutamate N-methyl-D-aspartate (NMDA) receptors have also been investigated in relation to neuropathological abnormalities in prefrontal areas of the brain of patients with schizophrenia. This may lead to new technologies like artificial networks related to the glutamate NMDA receptor system. New molecular biological techniques used in pharmacogenomics and proteomics offer new and exciting directions for future drug developments.