What is the Difference Between Aripiprazole and Risperidone

The key difference between Aripiprazole and Risperidone is that Aripiprazole is a third-generation atypical antipsychotic drug that acts as a partial dopamine D2 receptor agonist, while Risperidone is a second-generation atypical antipsychotic drug that acts a full dopamine antagonist.

Aripiprazole and Risperidone are atypical antipsychotics used to treat psychological disorders such as schizophrenia, bipolar disorder, and irritability associated with autism spectrum disorder. These drugs primarily block dopamine, a neurotransmitter that controls mood, thought, and behavior. Aripiprazole is a partial dopamine agonist, while Risperidone is a full dopamine antagonist. The different mechanisms of action of these two medications lead to different side effect profiles. In general, Aripiprazole has a lower risk of causing side effects than Risperidone. It is important to note that the best medication to treat these psychological disorders depends on the individual needs and preferences.

CONTENTS

1. Overview and Key Difference
2. What is Aripiprazole 
3. What is Risperidone
4. Similarities – Aripiprazole and Risperidone
5. Aripiprazole vs Risperidone in Tabular Form
6. Summary – Aripiprazole vs Risperidone

What is Aripiprazole?

Aripiprazole is an atypical antipsychotic prescribed for treating bipolar 1 disorder, autism-associated irritability, schizophrenia, and Tourette’s disorder. In addition, it is used as an adjunctive treatment for major depressive disorder. The antipsychotic action of Aripiprazole is attributed to the agonist activity of dopamine D2 and serotonin 5-HT_1A receptors and antagonist activity on 5-HT_2A receptors. Aripiprazole exhibits a high affinity towards both dopamine and serotonin receptors. The drug is available in tablets, syrups, and extended-release formulations.

Oral administration of Aripiprazole results in peak plasma concentrations within 3-5 hours due to the excellent absorption by the gastrointestinal tract. The absolute bioavailability of tablet formulation of Aripiprazole is 87% in the presence or absence of foods. After absorption, the drug is distributed through the body by binding it with the plasma proteins such as albumin. Aripiprazole is heavily metabolized in the liver by dehydrogenation, hydroxylation, and N-dealkylation. After metabolism, Aripiprazole is incorporated into the urine and feces with a half-life of 75 hours. The common adverse effects of Aripiprazole overdose include vomiting, somnolence, and tremor.

What is Risperidone?

Risperidone is a second-generation antipsychotic drug primarily prescribed to treat psychological disorders such as schizophrenia, psychosis, bipolar mania, severe depression, and specific behavioral symptoms in elderly patients with dementia. Risperidone inhibits D2 dopaminergic and 5-HT2A serotonergic receptors, reducing dopaminergic neurotransmission. The effect of Risperidone is believed to be transient, ultimately reducing psychiatric symptoms such as delusions and hallucinations. In addition, it results in a decreased risk of extrapyramidal symptoms associated with traditional antipsychotic drugs. Furthermore, Risperidone also antagonists the α1 and α2 histamine receptors; however, the precise mechanism is yet to be discovered.

Oral administration of Risperidone is well absorbed from the gastrointestinal tract with an absolute bioavailability of 70%. Most of the absorbed drug remains bound with plasma proteins. Then the drug is extensively metabolized into 9-hydroxy Risperidone by hepatic cytochrome p450 enzymes. After hepatic metabolism, metabolized and non-metabolized Risperidone is eliminated by urine with an elimination half-life of 3 hours. The overdose symptoms include lethargy, tachycardia, spasm, seizures, and bradycardia.

What are the Similarities Between Aripiprazole and Risperidone?

• Aripiprazole and Risperidone effectively treat psychological disorders such as schizophrenia and bipolar disorder.
• They are atypical antipsychotics.
• Both medications interact with dopamine receptors in the brain,
• Both drugs are generally well-tolerated, with a low risk of severe side effects.
• They are available in oral and injectable forms.

What is the Difference Between Aripiprazole and Risperidone?

Aripiprazole and Risperidone are effective atypical antipsychotic drugs with different mechanisms of action. Aripiprazole is an atypical partial dopamine D2 receptor agonist, while Risperidone is an atypical full dopamine antagonist. Aripiprazole is associated with a lower risk of movement disorders than antipsychotic medications and weight gain than Risperidone. Thus, this is the key difference between Aripiprazole and Risperidone. Furthermore, Aripiprazole has a faster onset of action than Risperidone. Aripiprazole is available as oral tablet solutions and intramuscular solutions and is associated with a lower risk of weight gain and sedation. In contrast, Risperidone has a higher risk of causing weight gain and metabolic effects.

Below is a summary of the difference between Aripiprazole and Risperidone in tabular form for side-by-side comparison.

Summary – Aripiprazole vs Risperidone

Aripiprazole and Risperidone are both atypical antipsychotics that are commonly prescribed to treat various mental health conditions. Although both drugs primarily target dopamine receptors, there is a specific difference between Aripiprazole and Risperidone. Aripiprazole is a partial dopamine D2 receptor agonist, while Risperidone is a full dopamine antagonist. As a result of this difference in mechanism of action, Aripiprazole has a lower risk of causing extrapyramidal side effects (EPS) than Risperidone. However, the best medication for individuals will depend on their needs and preferences. If anyone is considering taking either Aripiprazole or Risperidone, it is essential to talk to a doctor about the risks and benefits of each medication, and the doctor will decide which medication is best.

Reference:

1. McGavin, Jane K., and Karen L. Goa. “Aripiprazole.” CNS Drugs, vol. 16, no. 11, 2002, pp. 779–786.
2. Möller, Hans-Jürgen. “Risperidone: A Review.” Expert Opinion on Pharmacotherapy, vol. 6, no. 5, 2005, pp. 803–818.

Image Courtesy:

1. “Aripiprazole2D1” By Own work (CC BY 3.0) via Commons Wikimedia
2. “Risperidone” By Fvasconcellos (talk · contribs) – PubChem (Public Domain) via Commons Wikimedia