Atomoxetine

Definition

Atomoxetine is a prescription drug that is used to treat symptoms of impulsivity, inattentiveness, and hyperactivity, which are hallmark features of attention deficit hyperactivity disorder (ADHD). In the United States, atomoxetine is sold under the brand name Strattera.

Purpose

Atomoxetine is the only nonstimulant drug that has proven effective for alleviating all three of the hallmark features of ADHD. The drug is frequently used along with other psychological, educational, or social therapies in ADHD management.

Description

Atomoxetine is a selective norepinephrine inhibitor. By enhancing the activities of norepinephrine in certain areas of the brain, atomoxetine reduces chemical imbalances that are believed to contribute to ADHD symptoms.

Although the exact way that atomoxetine works in the brain is not well understood, the drug is believed to correct chemical imbalances between dopamine and norepinephrine. These two naturally occurring chemicals are commonly referred to as neurotransmitters . Their function is to regulate transmission of impulses from one cell to another. Atomoxetine may restore normal attention spans, correct impulsiveness, and calm hyperactivity by counteracting the neurotransmission abnormalities that cause symptoms of ADHD.

Before atomoxetine was approved by the FDA in 2002, all the drugs previously approved for ADHD were stimulants. Stimulants such as amphetamines have the potential to be abused and are sometimes sold illegally. As a result, strict rules are in place to monitor dispensing of prescription stimulants, and patients must obtain new prescriptions from their doctors each month. Because atomoxetine is not a stimulant, it is easy for patients to obtain refills for their medication and fewer physician visits are required. Many patients prefer atomoxetine over stimulants for the convenience the drug offers.

Recommended dosage

In adults or children weighing more than 150 lb (70 kg), the initial dose of atomoxetine is typically 40 mg taken once a day. The dosage can be increased after three days to 80 mg. This can be given either as a single dose in the morning or divided evenly in the morning and late afternoon. If a higher dosage is needed, the dose can be increased after 2–4 weeks to a maximum of 100 mg per day. The dosage must be lowered in individuals that have liver disease, since atomoxetine is broken down by the liver.

Atomoxetine should be initiated at a total daily dose of 1 mg/lb (0.5 mg/kg) in children that weigh less than 150 lb (70 kg). After at least three days, the dose can be increased to 2.4 mg/lb (1.2 mg/kg). Children may either take the entire dose in the morning or may split the dose evenly in the morning and late afternoon.

Improvements in ADHD symptoms may be noticed within 24 hours of first taking atomoxetine, although 3–4 weeks may be required for full benefits to be seen.

Precautions

Atomoxetine may cause changes in heart rate or blood pressure. As a result, this drug may not be appropriate for patients that have high blood pressure, rapid heartbeats, heart disease, or a history of strokes. Patients should have their blood pressure and pulse rate monitored when they start therapy and any time their dosage is increased.

Because of the possibility of severe eye damage, patients with a history of narrow angle glaucoma should not take atomoxetine. Since the liver breaks down the drug, patients with a history of liver disease should only be prescribed a low dose.

Patients who take dietary supplements, herbal remedies, or drugs that are available without a prescription should consult with their doctor prior to taking atomoxetine. It is best to avoid atomoxetine while pregnant and breastfeeding since its effects have not been studied during pregnancy and it is not known whether the drug is excreted in breast milk.

The drug may cause fatigue , dizziness , and headaches. Patients with a history of low blood pressure may be especially susceptible to these effects. It is best to avoid driving or operating heavy machinery until it is clear whether the drug will alter reaction time or impair judgment.

Side effects

The most common side effects associated with atomoxetine in children and teens are upset stomach, nausea, vomiting, decreased appetite, dizziness, tiredness, and mood swings.

In adults, the effects of constipation, dry mouth, nausea, decreased appetite, dizziness, sleeping difficulties, sexual side effects, difficulty urinating, and menstrual cramps are commonly attributed to atomoxetine.

If patients experience swelling or hives, they should not continue taking atomoxetine since serious allergic reactions may occur.

Interactions

Atomoxetine should not be used with certain types of antidepressants known as monoamine oxidase (MAO) inhibitors since this combination may cause blood pressure and heart rates to increase sharply. Muscle stiffness, muscle spasms, and even death can occur as a result of this drug interaction.

Atomoxetine may also increase heart rate and blood pressure when combined with albuterol, a drug that is commonly used to treat asthma.

Resources

BOOKS

Eli Lilly and Company Staff. Strattera Package Insert. Indianapolis, IN: Eli Lilly and Company, 2003.

Eli Lilly and Company Staff. Strattera Information for Patients or Their Parents or Caregivers Insert. Indianapolis, IN: Eli Lilly and Company, 2003.

Kelly Karpa, PhD, RPh