Aripiprazole

Absorption

Tablet: Aripiprazole is well absorbed after administration of the tablet, with peak plasma concentrations occurring within 3 hours to 5 hours; the absolute oral bioavailability of the tablet formulation is 87%. ABILIFY can be administered with or without food. Administration of a 15 mg ABILIFY tablet with a standard high-fat meal did not significantly affect the Cmax or AUC of aripiprazole or its active metabolite, dehydro-aripiprazole, but delayed Tmax by 3 hours for aripiprazole and 12 hours for dehydro-aripiprazole.
Oral Solution: Aripiprazole is well absorbed when administered orally as the solution. At equivalent doses, the plasma concentrations of aripiprazole from the solution were higher than that from the tablet formulation. In a relative bioavailability study comparing the pharmacokinetics of 30 mg aripiprazole as the oral solution to 30 mg aripiprazole tablets in healthy subjects, the solution-to-tablet ratios of geometric mean Cmax and AUC values were 122% and 114%, respectively. The single-dose pharmacokinetics of aripiprazole were linear and dose-proportional between the doses of 5 mg to 30 mg.
Extended-release injectable suspension, bimonthly injection: Aripiprazole absorption into the systemic circulation is prolonged following gluteal intramuscular injection due to the low solubility of aripiprazole particles. The release profile of aripiprazole from ABILIFY ASIMTUFII results in sustained plasma concentrations over 2 months following gluteal injection(s). Following multiple doses, the median peak:trough ratio for aripiprazole following an ABILIFY ASIMTUFII dose is 1.3, resulting in a flat plasma concentration profile with Tmax ranging between 1 to 49 days following multiple gluteal administrations of 960 mg.

Description

Aripiprazole was launched for the treatment of psychoses including schizophrenia and offers a novel mechanism of action as a partial D₂ receptor agonist. Aripiprazole can be synthesized in three steps beginning by the condensation of 7-hydroxy-1,2,3,4- tetrahydroquinolin-2-one with 1 ,Cdibromobutane followed by reaction with 1-(2,3- dichlorophenyl)piperazine. Aripiprazole is a significant D₂ agonist/antagonist, 5-HT₂ antagonist and 5-HT_1α agonist combined with minimal affinity for a,-adrenergic, H₁ and M₁ receptors. It has a low D4:D2 selectivity ratio and a D2:5-HT₂ affinity ratio that exceeds 15; resulting in different pharmacological characteristics compared to other atypical antipsychotics agents such as clozapine. In animal models, aripiprazole inhibits apomorphine-induced stereotypy without causing catalepsy and ptosis. Moreover, in contrast to classical antipsychotics that produce disabling movement disorders, aripiprazole does not cause an upregulation of D2 receptors or an increase in immediate early gene expression of e.g. the c-fos mRNA in the striatum. In patients with acute relapse of schizophrenia, treatment with aripiprazole provided significant improvement in both positive and negative syndrome scale (PANSS) total score in both short- and longterm evaluations. These results were comparable to those observed with haloperidol or risperidone; however, the early response rate was greater with aripiprazole. Aripiprazole was well tolerated with mild to moderate adverse events such as nausea, dizziness, somnolence and weight gain. The rates of extrapyramidal symptoms were lower than with haloperidol, prolactin levels increase has been uncommon and no significant Q-Tc interval prolongation was observed compared with placebo. Finally, studies suggested a minimal impact of aripiprazole administration on total cholesterol levels and on fasting blood sugar in contrast to other antipsychotics. Aripiprazole has a bioavailability of 87%, a t_max of 3-5 h and a half-life time of 48-68 h. Aripiprazole has been found to have linear kinetics and is mainly metabolized via the cytochrome systems CYP2D6 and CYP3A4. It has little effect on the blood levels of other medications; interaction with both lithium and divalproex sodium found minimal impact. Aripiprazole has also been studied in other psychiatric disorders, including bipolar disorders and has shown great efficacy.

The Uses of Aripiprazole

A deuterated version of Aripiprazole, a selective dopamine D2-receptor antagonist with dopamine autoreceptor agonist activity. Please note that users have reported separation of this compound and aripiprazole under normal-phase and reverse-phase

What are the applications of Application

Aripiprazole is a selective dopamine D2-receptor antagonist showing autoreceptor agonist activity

Background

Aripiprazole is an atypical antipsychotic orally indicated for the treatment of schizophrenia, bipolar I, major depressive disorder, irritability associated with autism, and Tourette's. It is also indicated as an injection for agitation associated with schizophrenia or bipolar mania. Aripiprazole exerts its effects through agonism of dopaminergic and 5-HT1A receptors and antagonism of alpha-adrenergic and 5-HT2A receptors. Aripiprazole was given FDA approval on November 15, 2002.

Indications

Aripiprazole is indicated for the treatment of acute manic and mixed episodes associated with bipolar I disorder, irritability associated with autism spectrum disorder, schizophrenia, and Tourette's disorder. It is also used as an adjunctive treatment of major depressive disorder.[L45859 An injectable formulation of aripiprazole is indicated for agitation associated with schizophrenia or bipolar mania. Finally, an extended-release, bimonthly injection formulation of aripiprazole is indicated for the treatment of adult schizophrenia and maintenance therapy for adult bipolar I disorder.

Pharmacokinetics

Aripiprazole exhibits high affinity for dopamine D2 and D3, serotonin 5-HT1a and 5-HT2a receptors (Ki values of 0.34 nM, 0.8 nM, 1.7 nM, and 3.4 nM, respectively), moderate affinity for dopamine D4, serotonin 5-HT2c and 5-HT7, alpha1-adrenergic and histamine H1 receptors (Ki values of 44 nM, 15 nM, 39 nM, 57 nM, and 61 nM, respectively), and moderate affinity for the serotonin reuptake site (Ki=98 nM). Aripiprazole has no appreciable affinity for cholinergic muscarinic receptors (IC50>1000 nM).

Metabolism

Aripiprazole is metabolized primarily by three biotransformation pathways: dehydrogenation, hydroxylation, and N-dealkylation. Based on in vitro studies, CYP3A4 and CYP2D6 enzymes are responsible for the dehydrogenation and hydroxylation of aripiprazole, and N-dealkylation is catalyzed by CYP3A4. Aripiprazole is the predominant drug moiety in systemic circulation. At steady-state, dehydro-aripiprazole, the active metabolite, represents about 40% of aripiprazole AUC in plasma.