Amisulpride

Drug Induced Liver Injury Rank (DILIrank 2.0)

Amisulpride

vLess-DILI-concern

3

Adverse reactions

DOI:10.1016/j.drudis.2016.02.015

Dopamine is an essential and critical neurotransmitter produced in the substantia nigra and ventral tegmental regions of the brain. Dopaminergic projection function in the nigrostriatal, mesolimbic, and mesocortical systems. Hyperactive dopamine transmission in the mesolimbic areas, or dopamine dysregulation in various major brain regions, is understood as the key driver of positive and negative symptoms of schizophrenia. Many antipsychotic agents act as D2 receptor antagonists, as with amisulpride. Amisulpride is a selective dopamine D2 and D3 receptor antagonist. It has high preferential activity towards dopamine receptors in the limbic system rather than the striatum, leading to a lower risk of extrapyramidal side effects than other atypical antipsychotic agents. At low doses, amisulpride reduces negative symptoms of schizophrenia by blocking pre-synaptic dopamine D2 and D3 receptors, increasing the levels of dopamine in the synaptic cleft and facilitating dopaminergic transmission. At higher doses, amisulpride blocks postsynaptic receptors, inhibiting dopaminergic hyperactivity: this explains the drug improving positive symptoms. Amisulpride also works as an antagonist at 5-HT_7A receptors and 5-HT_2A receptors, which may be related to its antidepressant effects. The chemoreceptor trigger zone (CTZ), also commonly known as the area postrema (AP), is an important brain region located within the dorsal surface of the medulla oblongata. CTZ is involved in emesis: it contains receptors, such as dopamine receptors, that are activated in response to emetic agents in the blood and relay information to the vomiting center, which is responsible for inducing the vomiting reflex. Amisulpride is an antiemetic agent that works to limit signals that promote nausea and vomiting. Amisulpride binds to D2 and D3 receptors in the CTZ, leading to reduced dopaminergic signalling into the vomiting center.

Elimination is biphasic. The elimination half-life of amisulpride is approximately 12 hours after an oral dose. The mean elimination half-life is approximately four to five hours in both healthy subjects and patients undergoing surgery receiving intravenous amisulpride.

Amisulpride undergoes minimal metabolism and its metabolites in plasma are largely undetectable. Two identified metabolites, formed by de-ethylation and oxidation, are pharmacologically inactive and account for approximately 4% of the dose. Metabolites remain largely uncharacterized. Metabolism of amisulpride does not involve cytochrome P450 enzymes.

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AMISULPRIDE

Established Pharmacologic Class [EPC] - Dopamine-2 Receptor Antagonist

Mechanisms of Action [MoA] - Dopamine D2 Antagonists

Amisulpride is a Dopamine-2 Receptor Antagonist. The mechanism of action of amisulpride is as a Dopamine D2 Antagonist.

AMISULPRIDE

Agents that control agitated psychotic behavior, alleviate acute psychotic states, reduce psychotic symptoms, and exert a quieting effect. They are used in SCHIZOPHRENIA; senile dementia; transient psychosis following surgery; or MYOCARDIAL INFARCTION; etc. These drugs are often referred to as neuroleptics alluding to the tendency to produce neurological side effects, but not all antipsychotics are likely to produce such effects. Many of these drugs may also be effective against nausea, emesis, and pruritus.

Drugs that bind to but do not activate DOPAMINE RECEPTORS, thereby blocking the actions of dopamine or exogenous agonists. Many drugs used in the treatment of psychotic disorders (ANTIPSYCHOTIC AGENTS) are dopamine antagonists, although their therapeutic effects may be due to long-term adjustments of the brain rather than to the acute effects of blocking dopamine receptors. Dopamine antagonists have been used for several other clinical purposes including as ANTIEMETICS, in the treatment of Tourette syndrome, and for hiccup. Dopamine receptor blockade is associated with NEUROLEPTIC MALIGNANT SYNDROME.

A structurally and mechanistically diverse group of drugs that are not tricyclics or monoamine oxidase inhibitors. The most clinically important appear to act selectively on serotonergic systems, especially by inhibiting serotonin reuptake.

Following oral administration, amisulpride is rapidly absorbed with absolute bioavailability of 48%. Amisulpride has two absorption peaks, with one rapidly achieved within one hour post-dose and a second peak occurring between three to four hours post-dose. Following oral administration of a 50 mg dose, two peak plasma concentrations were 39 ± 3 and 54 ± 4 ng/mL. Following intravenous administration, the peak plasma concentration of amisulpride is achieved at the end of the infusion period and the plasma concentration decreases by 50% within approximately 15 minutes. The AUC(0-∞) increases dose-proportionally in the dose range from 5 mg to 40 mg, which is about four times the maximum recommended dose. In healthy patients receiving intravenous amisulpride, the mean (SD) Cmax was 200 (139) ng/mL at the dose of 5 mg and 451 (230) ng/mL at the dose of 10 mg. The AUC ranged from 136 to 154 ng x h/mL in the dose range of 5 mg to 10 mg. In patients undergoing surgery, the mean (SD) Cmax ranged from 127 (62) to 161 (58) ng/mL at the dose of 5 mg. At the dose of 10 mg, it was 285 (446) ng/mL. The AUC ranged from 204 to 401 ng x h/mL.

Following intravenous administration, about 74% of amisulpride is excreted in urine, where 58% of the recovered dose was excreted as unchanged amisulpride. About 23% of the dose is excreted in feces, with 20% of the excreted dose as unchanged parent drug. Following intravenous administration, about four metabolites were identified in urine and feces, accounting for less than 7% of the total dose administered. About 22 to 25% of orally administered amisulpride is excreted in urine, mostly as the unchanged parent drug.

Following oral administration, the volume of distribution is 5.8 L/kg. Following intravenous infusion, the mean volume of distribution of amisulpride is estimated to be 127 to 144 L in surgical patients and 171 L in healthy subjects.

The plasma clearance of amisulpride is 20.6 L/h in surgical patients and 24.1 L/h in healthy subjects following intravenous administration. Renal clearance was estimated to be 20.5 L/hr (342 mL/min) in healthy subjects.