viloxazine

BRAND NAMES

Qelbree: This is the current, FDA-approved brand name for viloxazine extended-release capsules used to treat Attention-Deficit Hyperactivity Disorder (ADHD) in children (ages 6-17) and adults in the United States. It is manufactured by Supernus Pharmaceuticals. 

MECHANISM OF ACTION 

Viloxazine acts as a Serotonin–Norepinephrine Modulating Agent by primarily inhibiting the norepinephrine transporter (NET), which raises levels of norepinephrine and dopamine in the prefrontal cortex. It also influences serotonin activity through 5-HT2C receptor agonism and 5-HT2B receptor antagonism, resulting in improved neurotransmitter balance that helps alleviate ADHD symptoms.

PHARMACOKINETICS

Absorption

Viloxazine is quickly and efficiently absorbed following oral administration, showing a high absolute oral bioavailability of about 85–88%.

Distribution

After oral absorption, viloxazine is extensively distributed across body tissues, with about 76–82% bound to plasma proteins and a volume of distribution of approximately 0.73 L/kg.

Metabolism

Viloxazine is a selective norepinephrine reuptake inhibitor (sNRI) primarily used to treat Attention Deficit Hyperactivity Disorder (ADHD). Its metabolism is extensively hepatic and involves several distinct enzymatic pathways.

Excretion

Viloxazine is primarily excreted in the urine after being extensively metabolized by the liver. 

PHARMACODYNAMICS

Viloxazine’s pharmacodynamic action involves a dual mechanism as a serotonin–norepinephrine modulating agent (SNMA). Although its main therapeutic effect in ADHD is attributed to inhibition of norepinephrine reuptake, it also plays a significant role in modulating the serotonin system.

ADMINISTRATION

The capsule may be swallowed whole with water. For individuals who have trouble swallowing capsules, the contents can be opened and sprinkled onto a teaspoon of applesauce or pudding. The mixture should be swallowed without chewing and consumed completely—within 15 minutes when mixed with pudding or within 2 hours when mixed with applesauce. Any prepared mixture should not be stored for later use.

DOSAGE AND STRENGTH

Viloxazine is available as extended-release (ER) capsules in strengths of 100 mg, 150 mg, and 200 mg. The usual starting dose for children aged 6–11 years is 100 mg once daily, which may be increased to 200 mg, while adolescents (12–17 years) and adults typically start at 200 mg once daily, with a maximum of 400 mg if needed. It is taken once daily, preferably in the morning, with or without food, and dose adjustments may be required in patients with liver impairment.

DRUG INTERACTIONS

Viloxazine may interact with other medications that affect the liver enzyme CYP1A2, as it can increase the levels of drugs metabolized by this pathway, potentially raising the risk of side effects. It may also enhance the effects of other central nervous system-active drugs, such as antidepressants or stimulants, and caution is advised when taken with medications that influence blood pressure or heart rate. Additionally, combining viloxazine with monoamine oxidase inhibitors (MAOIs) or other serotonergic agents may increase the risk of serotonin-related side effects, so careful monitoring and dose adjustments may be necessary.

FOOD INTERACTIONS

Viloxazine can be taken with or without food, and there are no major dietary restrictions. However, consuming it with certain high-fat meals may slightly affect the rate of absorption, so it’s generally recommended to take it consistently—either always with food or always on an empty stomach—to maintain steady drug levels. Additionally, there are no known interactions with common foods or beverages, but patients should avoid alcohol, as it may increase side effects like drowsiness or dizziness.

CONTRAINDICATIONS

Viloxazine is contraindicated in individuals with a known hypersensitivity to viloxazine or any of its components. It should not be used in patients taking monoamine oxidase inhibitors (MAOIs) or within 14 days of discontinuing MAOI therapy due to the risk of serious drug interactions. Additionally, caution is advised in patients with severe liver impairment, as viloxazine is primarily metabolized by the liver.

SIDE EFFECTS

Nervous System: Drowsiness (somnolence), fatigue, headache, and difficulty sleeping (insomnia). Gastrointestinal: Nausea, vomiting, stomach or abdominal pain, reduced appetite, dry mouth, and constipation. Other: Irritability, upper respiratory tract infections, and fever. In Children: May experience changes in weight (children might not gain weight as expected for their age), so regular monitoring by a doctor is recommended. 

OVERDOSE

An overdose of viloxazine is usually classified as moderately toxic and, with appropriate supportive treatment, patients typically recover fully. Common signs of overdose include excessive sleepiness, fainting or reduced consciousness, and a rapid heartbeat. 

TOXICITY 

Viloxazine is moderately toxic in overdose, but full recovery is usually possible with supportive medical care. Common symptoms include drowsiness, loss of consciousness, and a rapid heart rate.