Antipsychotic and anticholinergic drugs

The discovery by Delay and Denicker in 1953 that chlorpromazine was highly effective in alleviating delusions, hallucinations, and disorganized thinking, was the seminal breakthrough in the treatment of schizophrenia, the first agent to produce sufficient relief of core psychotic symptoms to permit life outside of institutions for many patients with schizophrenia, and even a return to a semblance of function within normal limits. Chlorpromazine and the other related typical antipsychotic drugs which were introduced over the next 30 years have proven to be of immense benefit to vast numbers of people who experience psychotic symptoms as a component of a diverse group of neuropsychiatric and medical disorders, as well as drug-induced psychoses. These drugs have been invaluable in providing clues to the aetiology of schizophrenia and other forms of mental illness with psychotic features and as tools in understanding fundamental neural processes, especially those involving dopamine, a key neurotransmitter involved in psychosis. This class of drugs has now been supplanted by the so-called atypical antipsychotic drugs, of which clozapine is the prototype. This chapter will describe the various classes of antipsychotic agents, with emphasis on the atypical antipsychotic drugs, their benefits and adverse effects, recommendations for use in clinical practice, and mechanism of action. The drugs used to treat the extrapyramidal side-effects (EPS) produced mainly by the typical antipsychotic drugs are also considered.