Aripiprazole
Aripiprazole sold under the brand name Abilify®(Bristol-Myers Squibb) is the sixth, and most recent, of the second generation antipsychotic (or atypical antipsychotic) medications to hit the market. Aripirazole is FDA approved for the treatment of schizophrenia. Additionally, it has recently received FDA approval for the treatment of acute manic and mixed episodes associated with bipolar disorder.
Pharmacology
Aripirazole possesses a novel mechanism of action when compared to the other FDA approved atypical antipsychotics (i.e. clozapine,olanzapine, quetiapine, ziprasidone, and risperidone). Aripiprazole appears to mediate its antipsychotic effects primarily by partial agonism at the D2 receptor. Partial agonism at D2 receptors has been shown to modulate dopaminergic activity in areas where dopamine activity may be high or low, such as the mesolimbic and mesocortical areas of the schizophrenic brain, respectively. In addition to partial agonist activity at the D2 receptor, aripirazole is also a partial agonist at the 5-HT1A receptor, and like the other atypical antipsychotics, aripiprazole displays an antagonist profile at the 5-HT2A receptor. Aripiprazole has moderate affinity for histamine and alpha adrenergic receptors, and no appreciable affinity for cholinergic muscarinic receptors.
Pharmacokinetics
Aripiprazole displays linear kinetics with an elimination half-life of approximately 75 hours. Accordingly, steady state plasma concentrations are achieved in about 14 days. Cmax (maximum plasma concentration) is achieved in 3-5 hours after oral dosing. The bioavailabilty of the oral tablets is about 90%.
Metabolism
Aripiprazole is metabolized by the Cytochrome P450 isoenzymes 3A4 and 2D6. Accordingly, coadministration of aripiprazole with medications that may inhibit(e.g. paroxetine, fluoxetine) or induce (e.g. carbamazepine) these metabolic enzymes may increase or decrease, respectively, plasma concentrations of aripiprazole.
Adverse Events
Adverse events reported in the package insert for aripiprazole include headache, nausea, vomiting, somnolence, insomnia, and akathisia. It appears that aripirazole has a low incidence of EPS (extrapyramidal side effects). The risks of tardive dyskinesia with prolonged aripirazole use is unclear.
Dosage
15 to 30mg daily in a single dose. Dose titration does not seem to be necessary.
Dosage Forms
Aripirazole is available in 5mg, 10mg, 15mg, 20mg, and 30mg tablets.
Warnings About Medications with Similar Names
A warning has gone out recently because of this drug's name. The '-prazole' ending of this drug name makes this drug sound like it is one of the proton pump inhibitors (such as omeprazole, pantoprazole, lansoprazole) which are used in treating peptic ulcer disease. However, aripiprazole and these drugs are in an entirely different class of drugs altogether and confusing the two can lead to some unnecessary side effects.
Aripiprazole was develeloped by Otsuka Pharmaceutical Co., Ltd and is manufactured by the Bristol Myers Squibb pharmaceutical company (NYSE: BMY).
Aripiprazole was approved by the FDA on November 15, 2002.