Antipsychotics are drugs intended for the treatment of psychosis and other severe mental disorders. The group of antipsychotics includes a number of phenothiazine derivatives (chlorpromazine, etc.), butyrophenones (haloperidol, droperidol, etc.), diphenylbutylpiperidine derivatives (fluspirilene, etc.), etc.
Antipsychotics have a multifaceted effect on the body. Their main pharmacological features include a kind of calming effect, accompanied by a decrease in responses to external stimuli, weakening of psychomotor agitation and affective tension, suppression of fear, and weakening of aggressiveness. They are able to suppress delusions, hallucinations, automatism and other psychopathological syndromes and provide a therapeutic effect in patients with schizophrenia and other mental illnesses.
Antipsychotics do not have a pronounced hypnotic effect in normal doses, but they can cause a drowsy state, promote the onset of sleep and enhance the effect of hypnotics and other sedatives (sedatives). They potentiate the action of drugs, analgesics, local anesthetics and weaken the effects of psychostimulants.
In some neuroleptics, the antipsychotic effect is accompanied by a sedative effect (aliphatic phenothiazine derivatives: chlorpromazine, promazine, levomepromazine, etc.), while in others (piperazine phenothiazine derivatives: prochlorperazine, trifluoperazine, etc.; some butyrophenones) – activating energizers. Some antipsychotics can ease depression.
In the physiological mechanisms of the central action of neuroleptics, the inhibition of the reticular formation of the brain and the weakening of its activating effect on the cerebral cortex are essential. The various effects of neuroleptics are also associated with the effect on the occurrence and conduct of excitation in different parts of the central and peripheral nervous system.
Neuroleptics change neurochemical (mediator) processes in the brain: dopaminergic, adrenergic, serotonergic, GABAergic, cholinergic, neuropeptide and others. Different groups of antipsychotics and individual drugs differ in their effect on the formation, accumulation, release and metabolism of neurotransmitters and their interaction with receptors in different brain structures, which significantly affects their therapeutic and pharmacological properties.
Antipsychotics of different groups (phenothiazines, butyrophenones, etc.) block dopamine (D2) receptors of various brain structures. It is believed that this is mainly responsible for antipsychotic activity, while the inhibition of central noradrenergic receptors (in particular, in the reticular formation) is only sedative. The inhibition of the mediator activity of dopamine is largely associated not only with the antipsychotic effect of neuroleptics, but also the neuroleptic syndrome caused by them (extrapyramidal disorders), explained by the blockade of dopaminergic structures of the subcortical formations of the brain (substantia nigra and striatum, tubercular, interlimbic and mesocortical regions), where significant amount of dopamine receptors.
The effect on central dopamine receptors leads to some endocrine disorders caused by neuroleptics. By blocking the dopamine receptors of the pituitary gland, they increase the secretion of prolactin and stimulate lactation, and by acting on the hypothalamus, they inhibit the secretion of corticotropin and growth hormone.
Clozapine, a piperazino-dibenzodiazepine derivative, is a neuroleptic with pronounced antipsychotic activity, but practically not causing extrapyramidal side effects. This feature of the drug is associated with its anticholinergic properties.
Most antipsychotics are well absorbed by different routes of administration (inside, intramuscularly), penetrates the BBB, but accumulates in the brain in much smaller amounts than in internal organs (liver, lungs), is metabolized in the liver and excreted in the urine, partly in the intestines. They have a relatively short half-life and, after a single use, act for a short time. Prolonged-release drugs (haloperidol decanoate, fluphenazine, etc.) have been created, which, when administered parenterally or when taken orally, have a long-term effect.
Below is a list of antipsychotics:
- Alimemazine tartrate
- Alimemazine tartrate