What is Atomoxetine?
Atomoxetine, also available under the brand name Strattera, is a selective norepinephrine reuptake inhibitor (NRI) used to treat Attention-Deficit/Hyperactivity Disorder (ADHD). Unlike many other ADHD medications, it is not a stimulant and is not a controlled substance, which means it has a low potential for misuse and dependence. It is approved for use in both adults and children aged six years and older. Atomoxetine is considered a second-line treatment for ADHD, often prescribed when stimulants are ineffective, not tolerated, or contraindicated due to risks like a history of substance abuse. It is most effective as part of a comprehensive treatment plan that includes counseling, education, and other psychosocial measures.
The Specific Role of Atomoxetine 18 mg
The 18 mg dosage is one of several capsule strengths available, including 10 mg, 25 mg, 40 mg, 60 mg, 80 mg, and 100 mg. The specific use of the 18 mg dose depends on the patient's age and weight, and where they are in their treatment regimen. It is most commonly used during the titration phase of treatment for children and adolescents.
Dosing and Titration
For children and adolescents weighing less than 70 kg, dosing is based on body weight. The treatment typically starts at a lower dose, often 0.5 mg/kg per day, and is gradually increased over several days or weeks to a target dose of 1.2 mg/kg per day. An 18 mg dose could be a starting dose or an intermediate step during this titration process for a child. For example, a child weighing approximately 36 kg (about 80 lbs) might receive 18 mg as part of their dose. In adults and adolescents over 70 kg, the starting dose is higher (40 mg per day), and the dose is adjusted from there, so 18 mg is not a typical starting or maintenance dose.
Administration
Patients can take atomoxetine once daily in the morning or in two evenly divided doses in the morning and late afternoon/early evening. It can be taken with or without food, though taking it with food may help reduce nausea or stomach upset. Capsules should always be swallowed whole and should not be opened, crushed, or chewed.
How Atomoxetine Works
Atomoxetine's mechanism of action involves increasing the levels of norepinephrine in the brain. It does this by selectively inhibiting the presynaptic norepinephrine transporter (NET). This blocking action allows more norepinephrine and, importantly, dopamine in the prefrontal cortex to be available for longer periods. This increase in neurotransmitters helps to improve the symptoms of ADHD, such as:
- Sustained attention and concentration
- Impulse control and executive functioning
- Reduction in hyperactivity
Unlike stimulants, atomoxetine does not increase dopamine levels in the brain's reward centers (the striatum or nucleus accumbens). This is why it has a lower potential for abuse and is not a controlled substance. The full therapeutic effect of atomoxetine is not immediate and may take up to 4 to 8 weeks to be fully realized.
Side Effects and Safety Considerations
Like all medications, atomoxetine comes with potential side effects. Patients and caregivers should be aware of both common and serious risks.
Common Side Effects
- Nausea and stomach upset
- Decreased appetite and weight loss
- Fatigue, tiredness, or somnolence
- Dizziness
- Dry mouth
- Insomnia
- Constipation
- Changes in mood or irritability
Serious Side Effects and Boxed Warning
The FDA has issued a boxed warning for atomoxetine concerning an increased risk of suicidal ideation (thinking about or planning suicide) in children and adolescents, especially during the first few months of treatment or following a dosage change. Other serious side effects include:
- Cardiovascular Events: Atomoxetine can increase heart rate and blood pressure, with a rare but serious risk of heart attack, stroke, and sudden death, especially in patients with pre-existing heart problems.
- Liver Problems: Rare cases of severe liver injury have been reported. Signs include jaundice (yellowing of the skin or eyes), upper right abdominal pain, and dark urine.
- Behavioral Changes: New or worsening mental health symptoms, such as anxiety, aggression, hostility, or manic episodes, may occur.
- Prolonged Erections: In rare instances, males may experience a painful or prolonged erection (priapism), which requires immediate medical attention.
Comparison: Atomoxetine vs. Stimulants
Atomoxetine's properties as a non-stimulant set it apart from traditional ADHD medications like Adderall (mixed amphetamine salts) and Ritalin (methylphenidate).
| Feature | Atomoxetine (Non-stimulant) | Stimulants (e.g., Adderall, Ritalin) |
|---|---|---|
| Mechanism | Selective Norepinephrine Reuptake Inhibitor (NRI) | Increase norepinephrine and dopamine in the brain |
| Onset of Action | Slower; weeks to reach full effect | Rapid; hours to take effect |
| Abuse Potential | Low; not a controlled substance | High; controlled substance (Schedule II) |
| Best For | Individuals who do not respond to stimulants, cannot tolerate their side effects, or have a history of substance abuse | Often the first-line treatment for most people with ADHD due to rapid symptom relief |
| Duration of Effect | Provides 24-hour symptom coverage, often with once-daily dosing | Varies by formulation; can require multiple doses per day |
Contraindications and Monitoring
Atomoxetine should not be used in patients with certain pre-existing conditions and requires careful monitoring. Contraindications include:
- Use within 14 days of taking a Monoamine Oxidase Inhibitor (MAOI)
- Narrow-angle glaucoma
- Severe heart or blood vessel problems
- Pheochromocytoma (a tumor of the adrenal gland)
Regular monitoring of heart rate and blood pressure is recommended during treatment, and growth and weight should be tracked in children and adolescents. Any signs of liver problems, suicidal thoughts, or unusual behavior should be reported to a doctor immediately. For more information on dosing and safety, please consult the FDA's detailed labeling for Strattera.
Conclusion
Atomoxetine 18 mg plays a specific and important role in the comprehensive treatment of ADHD, primarily as a titration dose for children and adolescents whose weight-based dosing starts in this range. As a non-stimulant, it offers a valuable alternative for patients who cannot use or do not respond to traditional stimulants, providing sustained symptom control with a lower risk of abuse. However, its use requires careful consideration of its potential side effects and a commitment to close medical supervision, especially regarding the boxed warning for suicidal ideation in pediatric patients. For personalized and safe treatment, it is crucial to follow a healthcare provider's directions precisely.
