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Neuroleptics

The term "neuroleptics" (neuroleptic drugs) was proposed back in 1967, when the first classification of psychotropic drugs was developed. They designated funds intended for the treatment of severe CNS diseases (psychosis). Recently, in a number of countries, it has been considered appropriate to replace this term with the term "antipsychotics", since "neuroleptic syndrome" is not a primary but an undesirable side effect, which complicates the therapeutic effect of the drugs of this group. The modern task is the creation of antipsychotic drugs that are devoid of an antipsychotic component. Nevertheless, the term "neuroleptics" continues to be widely used to refer to this group of drugs.
The group of neuroleptic drugs includes a number of phenothiazine derivatives (aminazine, etc.), butyrophenones (haloperidol, etc.), diphenylbutylpiperidine derivatives (flushpyrilene, etc.) and other chemical groups. One of the first neuroleptic drugs was also the alkaloid reserpine. Currently, due to the relatively low antipsychotic activity, it gave way to more effective modern drugs, but it retained its value as an antihypertensive agent.
Neuroleptics have a multifaceted effect on the body. One of their main pharmacological features is a kind of calming effect, accompanied by a decrease in responses to external stimuli, a weakening of psychomotor agitation and affective tension, a suppression of a sense of fear, a weakening of aggression. Their main feature is the ability to suppress delusions, hallucinations, automatism and other psychopathological syndromes and have a therapeutic effect in patients with schizophrenia and other mental illnesses.
Pronounced sleeping pills neuroleptics in normal doses do not have, but can cause a drowsy condition and promote sleep onset. They increase the effect of hypnotics and other soothing (sedative) drugs, also potentiate the effects of drugs, analgesics, local anesthetics and weaken the effects of psychostimulating drugs (phenamine, etc.).
A number of neuroleptics (phenothiazine, butyrophenone, etc.) has antiemetic activity; This effect is associated with selective inhibition of chemoreceptor trigger (trigger) zones of the medulla oblongata.
For a number of neuroleptics, the ability to have a catalytic effect is characteristic.
There are antipsychotics whose antipsychotic effect is accompanied by sedative (aliphatic derivatives of phenothiazine, reserpine, etc.) or an activating (energizing) effect (piperazine derivatives of phenothiazine, some butyrophenones). Some neuroleptics have elements of antidepressant action.
These and other pharmacological properties of various neuroleptic drugs are expressed in varying degrees. The combination of these and other properties with the main antipsychotic effect determines the profile of their action and indications for use in psychiatry and other fields of medicine.
In the physiological mechanisms of the central action of neuroleptics, their influence on the reticular formation of the brain is essential; Exerting a depressing effect on this part of the brain, neuroleptics eliminate its activating influence on the cerebral cortex. The action of neuroleptics is not limited, however, to the effect on the reticular formation. Their various effects are also associated with the effect on the occurrence and conduction of excitation in different parts of the central and peripheral nervous system.
From neurochemical mechanisms of action of neuroleptics, their influence on mediator processes in the brain has been studied most. At the present time, a lot of data have been accumulated on the effect of neuroleptics (and other psychotropic drugs) on adrenergic, dopaminergic, serotonergic, GABAergic, cholinergic and other neurotransmitter processes, including effects on neuropeptide systems of the brain.
Different groups of neuroleptics and individual drugs, as well as psychotropic drugs of other groups, differ in their influence on the formation, accumulation, release of the metabolism of various neurotransmitters and their interaction with receptors in different brain structures, which significantly affects their pharmacological properties and therapeutic effectiveness.
Recently, much attention has been paid to the interaction of neuroleptics with dopamine structures of the brain. According to modern data, dopamine, which is a precursor in the process of norepinephrine biosynthesis, has an independent significance as a chemical mediator of nerve impulses in certain structures of the brain and plays an important role in the processes of nervous activity. It was found that the disturbance of the mediator function of dopamine is one of the pathogenetic mechanisms of the development of Parkinsonism and other extrapyramidal disorders (see Dopamine, Means for the Treatment of Parkinsonism). Changes in the formation and function of dopamine are also observed in various psychopathological conditions. There is reason to believe that the influence on dopaminergic processes plays an important role in the mechanism of action of neuroleptics, although they also act on other mediator systems.
It has been shown that neuroleptics of different groups (phenothiazines, butyrophenones, etc.) block the dopamine receptors of different brain structures. It is believed that this action causes antipsychotic activity, and the inhibition of central noradrenergic receptors (in particular, in the reticular formation) causes predominantly a sedative effect, as well as hypotensive effects observed in the clinic.
The "target" for neuroleptics are mainly D-receptors (see Dopamine).
With the inhibition of the mediator activity of dopamine, not only the antipsychotic activity of antipsychotics is associated, but also the main side effect, called "neuroleptic syndrome" (extrapyramidal disorders similar to parkinsonism). This action is explained by the blocking effect of neuroleptics on the subcortical formations of the brain (black substance and the striatum, tubercular, interlimbic and mesocortical regions), where a significant number of receptors sensitive to dopamine are located. Of the most known neuroleptics, noradrenergic receptors are more strongly affected by aminazine, levomepromazine, thioridazine, dopaminergic - fluorophenazine, haloperidol, sulpiride.
Adverse extrapyramidal effects do not completely correlate with the antipsychotic activity of different neuroleptics, which indicates the unequal sensitivity of various dopaminergic structures of the brain to different chemical compounds; This creates prospects for obtaining neuroleptics with a selective antipsychotic effect without pronounced side effects of extrapyramidal effects. It was also noted that a lesser side effect of extrapyramidal action is usually observed in neuroleptics with greater anticholinergic activity. Indeed, compounds that have anticholinergic properties have an antiparkinsonian effect.
One of the neuroleptics with pronounced antipsychotic activity, which does not cause extrapyramidal side effect, is azaleptin (syn: clozapine, leponex) - a derivative of piperazino-dibenzodiazepine.
It should be noted that the neuroleptics that cause more pronounced extrapyramidal phenomena have the strongest catalytic activity under the experimental conditions, which can explain the blocking of dopamine receptors and allows us to foresee the possibility of extrapyramidal disorders on the basis of the experimental study.
The effect on the central dopamine receptors explains the mechanism of some of the endocrine disorders caused by neurolepticamine, including stimulation of lactation. By blocking the dopamine receptors of the pituitary gland, neuroleptics increase the secretion of prolactin. Acting on the hypothalamus, neuroleptics also inhibit the secretion of corticotropin and growth hormone.
Pharmacokinetically, most neuroleptics are characterized by good absorption at different routes of administration (by mouth, intramuscularly). They penetrate the blood-brain barrier, but accumulate in the brain in much smaller quantities than in the internal organs (liver, lungs). Metabolised in the liver and excreted in significant quantities with urine, in part - with feces.
Most "conventional" neuroleptics have a relatively short half-life in the body and have a short-term effect after a single administration. Special preparations of prolonged action have been created (see Fluorphenazine-decanoate, Flushpyrilene, Pimozide, etc.), which have a long-term effect with parenteral administration or ingestion.

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Subgroup Psychotropic drugs include drugs: