Table of Contents
Aripiprazole is an atypical antipsychotic medication primarily used to treat schizophrenia, bipolar disorder, and irritability associated with autism. Understanding its pharmacology is essential for students preparing for exams in pharmacology or psychiatry.
Mechanism of Action
Aripiprazole functions as a partial agonist at dopamine D2 receptors and serotonin 5-HT1A receptors, and as an antagonist at serotonin 5-HT2A receptors. This unique mechanism helps balance neurotransmitter activity, reducing psychotic symptoms while minimizing side effects associated with dopamine blockade.
Pharmacokinetics
Aripiprazole is well-absorbed orally with a bioavailability of approximately 87%. It undergoes extensive hepatic metabolism primarily via the CYP2D6 and CYP3A4 enzymes. The drug has a long half-life of about 75 hours, allowing once-daily dosing.
Therapeutic Uses
- Schizophrenia
- Bipolar disorder (manic and mixed episodes)
- Autism-related irritability
- Major depressive disorder (adjunct therapy)
Side Effects and Precautions
- Akathisia and restlessness
- Weight gain and metabolic changes
- Somnolence
- Potential for extrapyramidal symptoms
- Monitoring for cardiovascular effects such as orthostatic hypotension
Drug Interactions
- Strong CYP2D6 and CYP3A4 inhibitors or inducers can alter aripiprazole levels
- Concomitant use with other CNS depressants may increase sedation
- Monitoring is necessary when combined with medications affecting dopamine or serotonin pathways
Summary
Aripiprazole’s unique partial agonist activity at dopamine and serotonin receptors makes it a versatile and effective medication for various psychiatric conditions. Its pharmacokinetic profile supports once-daily dosing, but clinicians and students must be aware of its side effects and drug interactions to optimize therapy and ensure safety.