Why does someone experience somnolence on Strattera (Atomoxetine)?

From the Guidelines

Feeling sleepy on Strattera is a common side effect, particularly when first starting the medication or after dose increases, due to its impact on norepinephrine levels in the brain, which can affect arousal and energy systems 1. This drowsiness is often temporary and tends to improve after a few weeks as the body adjusts to the medication. According to the most recent evidence, the most common adverse effects of atomoxetine in child and adolescent clinical trials were nausea, vomiting, fatigue, decreased appetite, abdominal pain, and somnolence 1. Some key points to consider:

• Taking Strattera at night instead of in the morning may help manage this side effect.
• If drowsiness persists or is severe, it's essential to consult with a healthcare provider, who might adjust the dosage or recommend taking the medication at a different time of day.
• Other factors like individual metabolism, concurrent medications, or underlying health conditions can also influence how Strattera affects energy levels.
• It's crucial to monitor for suicidality, clinical worsening, and unusual changes of behavior, especially during the first few months of treatment or at times of dose change, as analyses of twelve placebo-controlled trials in children and adolescents showed a greater risk of suicidal ideation during treatment with atomoxetine 1.
• The medication should be used with caution in patients with preexisting cardiovascular diseases or significant cardiac abnormalities, as it may increase heart rate and blood pressure to a mild and clinically insignificant degree, but can lead to more substantial increases in a subset of individuals 1.

From the FDA Drug Label

Somnolence includes the terms: sedation, somnolence The most commonly observed adverse reactions in patients treated with atomoxetine hydrochloride (incidence of 5% or greater and at least twice the incidence in placebo patients, for either BID or QD dosing) were: nausea, vomiting, fatigue, decreased appetite, abdominal pain, and somnolence Among atomoxetine hydrochloride-treated patients, irritability (0.3%, N=5); somnolence (0.3%, N=5); The most commonly reported symptoms accompanying acute and chronic overdoses of atomoxetine hydrochloride were gastrointestinal symptoms, somnolence, dizziness, tremor, and abnormal behavior.

Somnolence is a reported side effect of atomoxetine, which can cause patients to feel sleepy. The exact mechanism of how atomoxetine causes somnolence is not fully understood, but it is thought to be related to its inhibition of the pre-synaptic norepinephrine transporter.

• Key points:
  • Somnolence is a common adverse reaction associated with atomoxetine.
  • The incidence of somnolence is at least 5% or greater and at least twice the incidence in placebo patients.
  • Somnolence has been reported in both child and adolescent patients, as well as adult patients.
  • The mechanism of somnolence is not fully understood, but it is thought to be related to the inhibition of the pre-synaptic norepinephrine transporter 2.

From the Research

Possible Reasons for Sleepiness on Strattera

• Sleepiness, also known as somnolence, is a common adverse event associated with atomoxetine (Strattera) treatment, as reported in several studies 3, 4, 5.
• The exact mechanism of atomoxetine-induced sleepiness is unclear, but it may be related to its selective inhibition of presynaptic norepinephrine reuptake in the prefrontal cortex 3, 6.
• Atomoxetine has a high affinity and selectivity for norepinephrine transporters, which may contribute to its sedative effects 3, 4.
• A study found that atomoxetine was associated with a high reporting odds ratio of somnolence, ranking second among 30 antidepressants assessed 4.
• Another study found that atomoxetine improved sleepiness in patients with mild to moderate obstructive sleep apnea with excessive sleepiness, but did not improve the respiratory disturbance index 7.

Factors Influencing Sleepiness on Strattera

• The dosage regimen of atomoxetine may influence the risk of sleepiness, with higher doses potentially increasing the risk of somnolence 5, 6.
• Individual differences in cytochrome P450 2D6 (CYP2D6) metabolism may also affect the risk of sleepiness, as poor metabolizers may have greater exposure to atomoxetine and slower elimination 3, 6.
• The presence of comorbidities, such as anxiety or depression, may also influence the risk of sleepiness in patients taking atomoxetine 5, 6.