Antipsychotics when administered orally are absorbed Variably from the gastrointestinal tract, with uneven blood levels. They are highly bound to both plasma and tissue proteins. The concentration of the brain is higher than the plasma concentration. They are metabolized in the liver and excreted mainly through the kidneys. The elimination half varies from 10 to 24 hours a day. Most antipsychotics tend to have a therapeutic window. If the blood level is below this window, the drug will be ineffective. If the blood level is higher than the upper limit of the window, the result will be toxic or the drug will be ineffective again.
Mechanism of action:
Drug antipsychotics block D2 receptors in the mesolimbic and mesofrontal (emotional) systems. Sedation is caused by an alpha-adrenergic blockade. Anti-dopaminergic activity on basal ganglia is responsible for inducing ESP (Extrapyramidal symptoms) antipsychotic antiserotonergic activity (5-hydroxytryptamine or 5-HT)Action against antiadrenergic and antihistamines. These are also called serotonin-dopamine antagonists.