Atomoxetine is a non-stimulant medication prescribed for Attention-Deficit/Hyperactivity Disorder (ADHD) in children. It is designed to help improve attention span while reducing impulsivity and hyperactivity by increasing the amount of a chemical in the brain called norepinephrine. This medication may be used as one component of a broader treatment program that also involves social, educational, and psychological therapies. Determining the correct dosage for a child is a careful process managed by a healthcare professional.
Initial and Target Dosage Calculation
The primary factor a doctor considers when determining the initial dose of atomoxetine for a child is their body weight. For children and adolescents who weigh 70 kilograms (about 154 pounds) or less, treatment begins with a starting dose calculated at 0.5 milligrams per kilogram of body weight per day (0.5 mg/kg/day). For example, a child weighing 30 kilograms (about 66 pounds) would receive an initial daily dose of 15 milligrams.
After this initial phase, the physician establishes a “target dose,” which is the amount aimed for to achieve the desired therapeutic effect. This target is also based on weight, set at 1.2 mg/kg/day. Using the same 30-kilogram child, the target dose would be 36 milligrams per day. The available capsule strengths are considered when prescribing the final amount.
For children weighing over 70 kilograms, the dosing strategy shifts from a weight-based calculation to a fixed-dose approach. In these cases, treatment starts at a flat 40 milligrams per day. Regardless of weight, there is a maximum recommended dose, which is the lesser of 1.4 mg/kg/day or 100 mg per day, to ensure safety.
The Titration Process
The journey from the initial dose to the target dose is a gradual process known as titration. This slow increase is implemented to allow the child’s body to acclimate to the medication. It also gives the physician an opportunity to monitor for any potential side effects at each dosage level before proceeding to the next.
A titration schedule involves maintaining the starting dose for a minimum of three to seven days before making the first adjustment upward. After this initial period, and assuming the medication is well-tolerated, the dose is increased toward the calculated target. Further adjustments may be considered after two to four additional weeks if the child’s symptoms have not improved sufficiently.
Throughout this period, communication between parents and the prescribing doctor is important. Parents are instructed to observe their child’s response to the medication, noting any changes in ADHD symptoms as well as the emergence of any side effects like changes in mood, sleep patterns, or appetite.
Administration and Timing Guidelines
The medication is commonly administered once daily in the morning. This timing helps provide coverage for school hours and daily activities when focus is most needed. An alternative approach is to split the total daily dose into two, with one taken in the morning and a second in the late afternoon or early evening. This split schedule can help reduce side effects like stomach upset or sleepiness.
Atomoxetine can be taken with or without food, as food does not significantly impact its absorption. However, taking it with a meal may help prevent an upset stomach. The capsules must be swallowed whole and never opened, crushed, or chewed, as the contents can be an irritant.
For a once-daily dose that is missed, it can be taken as soon as it is remembered, but it should be skipped if it is close to the next day’s scheduled time. For a twice-daily schedule, a missed dose can be taken if remembered within a few hours. A double dose should never be taken to make up for a missed one.
Factors That May Require Dosage Adjustments
While weight-based calculations provide a standard framework, a doctor may need to adjust a child’s atomoxetine dosage based on several individual factors. A child’s specific response and how well they tolerate the medication are primary considerations. If a child experiences persistent or bothersome side effects, the doctor may decide to lower the dose, slow the titration schedule, or in some cases, discontinue the medication.
A significant factor influencing dosage is the child’s liver function, specifically related to an enzyme known as CYP2D6. This enzyme is responsible for metabolizing atomoxetine in the body. Some individuals are “poor metabolizers” due to their genetic makeup, meaning they break down the drug more slowly, leading to higher concentrations in the blood. For these children, a doctor will start with the standard 0.5 mg/kg/day dose but will only increase it if symptoms do not improve after four weeks and the initial dose is well-tolerated.
The co-administration of other medications can also necessitate a dosage adjustment. Certain drugs, such as some antidepressants like fluoxetine and paroxetine, are strong inhibitors of the CYP2D6 enzyme. When taken alongside atomoxetine, these medications can mimic the effect seen in poor metabolizers, increasing the drug’s concentration. In such cases, a similar, more cautious titration approach is used to prevent an excessive buildup of atomoxetine.