Viloxazine

Introduction Overview

Generic Name

viloxazine

Brand Name

Qelbree

Dosage Form

Extended-release capsules (100 mg, 150 mg, 200 mg)

Drug Class

Adrenergic uptake inhibitors for ADHD

Pharmacokinetics

Absorption:
Qelbree (viloxazine extended-release) is absorbed following oral administration with a pharmacokinetic profile designed to provide 24-hour sustained therapeutic levels. Peak plasma concentrations (Cmax) are typically reached between 5 to 8 hours post-dose, supporting once-daily dosing. The presence of food does not significantly alter the bioavailability, allowing administration with or without meals. The extended-release formulation contributes to smooth plasma concentration profiles, minimizing peak-trough fluctuations and reducing side effects associated with peak plasma levels.

Distribution:
Viloxazine exhibits moderate plasma protein binding, approximately 76%, mainly to albumin. It distributes widely throughout the body with a volume of distribution (Vd) indicative of good tissue penetration, including central nervous system penetration, which is essential for its efficacy in ADHD treatment. The ability to cross the blood-brain barrier allows viloxazine to modulate central norepinephrine levels. Distribution can be affected by patient-specific factors such as age, body weight, and plasma protein levels.

Metabolism:
Viloxazine undergoes extensive hepatic metabolism primarily through hydroxylation and conjugation pathways. The principal metabolic enzymes involve cytochrome P450 isoforms, although the exact contribution of individual CYP enzymes appears limited, reducing the potential for extensive CYP-mediated drug interactions. Metabolites are pharmacologically inactive. The hepatic metabolic pathway includes hydroxylation followed by glucuronidation, making the drug extensively metabolized in the liver before elimination.

Elimination:
The elimination of viloxazine and its metabolites occurs mainly via renal excretion. Approximately 90% of the dose is recovered in urine, primarily as metabolites, with less than 5% excreted unchanged. The elimination half-life of viloxazine is approximately 7 hours in adults, consistent with its extended-release formulation facilitating once-daily dosing. Renal function influences elimination, and dose adjustments may be necessary in severe renal impairment. Viloxazine is not significantly eliminated via feces, and biliary excretion is minimal. Understanding elimination pathways is critical in populations with hepatic or renal impairments to avoid accumulation and toxicity.

Dosage Forms

Available Dosage Forms:
- Extended-release capsules available in 100 mg, 150 mg, and 200 mg strengths.

Dosages for Adults and Adolescents:
- Adults: Initial dose of 200 mg once daily, titrating weekly by 200 mg increments as tolerated to a maximum of 600 mg daily.
- Adolescents (12 to 17 years): Initial dose of 200 mg once daily, which after 1 week may be increased to 400 mg daily based on response and tolerability. Maximum dose is 400 mg daily.

Dosages for Pediatric Patients:
- Children (6 to 11 years): Start with 100 mg once daily, titrating weekly by 100 mg increments based on efficacy and tolerability. Maximum recommended dose is 400 mg daily.

Specific Patient Populations:
- Pediatric patients (6 years and older) have defined dosing regimens emphasizing cautious titration.
- Adults may require higher maximum doses, with ongoing monitoring of cardiovascular status.
- Dosing adjustments and monitoring are recommended in patients with severe renal or hepatic impairment due to altered metabolism and elimination.
- The capsules are intended to be swallowed whole but may be opened and contents mixed with applesauce for patients unable to swallow capsules, ensuring full dose administration without chewing.

Mechanism Of Action

Qelbree (viloxazine) acts primarily as a selective norepinephrine reuptake inhibitor (NRI), targeting the presynaptic norepinephrine transporter (NET). By blocking the NET, viloxazine increases extracellular norepinephrine concentrations in critical areas of the brain such as the prefrontal cortex and locus coeruleus, regions implicated in attention regulation and impulse control. This increase in norepinephrine enhances neurotransmission and neuronal communication, which are thought to ameliorate core ADHD symptoms such as inattention, impulsivity, and hyperactivity.

In addition to its norepinephrine reuptake inhibition, preclinical studies suggest that viloxazine may have modulatory effects on serotonergic pathways, influencing serotonin receptor subtypes and serotonin transporter activity to a limited degree. This serotonergic activity may contribute to mood stabilization and a potentially favorable side effect profile relative to other ADHD medications. However, the norepinephrine reuptake inhibition remains the primary mechanism responsible for its therapeutic effect in ADHD.

Unlike stimulant medications, Qelbree does not act through dopamine release or significant dopamine transporter inhibition, reducing the risk of abuse potential and stimulant-related adverse effects. This unique mechanism distinguishes viloxazine from traditional stimulant agents such as amphetamines and methylphenidate.

Clinically, the enhancement of norepinephrine neurotransmission via viloxazine leads to improved executive functions, including working memory, attention span, and behavioral control. This translates into reduced ADHD symptomatology. Research trials demonstrate that these neurochemical effects contribute to symptom improvements observed as early as the first to second week of treatment, with continued benefits upon sustained administration.

Pharmacological Actions

Selective norepinephrine reuptake inhibition leading to increased central norepinephrine levels.
Modulation of serotonergic neurotransmission contributing to mood stabilization.
Extended-release formulation allowing stable plasma levels and 24-hour efficacy.
Improvement of attention, impulse control, and hyperactivity through enhanced catecholaminergic signaling.
Non-stimulant mechanism reduces abuse potential compared to amphetamine or methylphenidate products.
Minimal dopaminergic activity, potentially resulting in fewer stimulant-related side effects.
Potential anxiolytic effects secondary to modulation of norepinephrine and serotonin pathways.
Titrated dosing enables individualized therapy to optimize therapeutic response and tolerability.
Demonstrated efficacy in both pediatric and adult ADHD populations through randomized clinical trials.
Improvement in executive function and behavioral regulation associated with enhanced prefrontal cortex activity.

Therapeutic Or Clinical Uses

Treatment of Attention Deficit Hyperactivity Disorder (ADHD) in children aged 6 years and older.
Management of ADHD symptoms in adolescents and adults.
Reduction of core ADHD symptoms including inattention, hyperactivity, and impulsivity.
Alternative non-stimulant therapy option for patients who cannot tolerate or do not respond to stimulants.
Pharmacologic option for patients at risk of stimulant abuse or with comorbid conditions precluding stimulants.
Adjunct treatment in comprehensive ADHD management programs including behavioral therapies.
Maintenance therapy for extended periods to control chronic ADHD symptomatology.
Management of patients with ADHD who have coexisting mood or anxiety symptoms due to serotonergic activity.
Use in patients where dose flexibility and gradual titration are required due to comorbidities or sensitivity.
Consideration for use in patients with cardiovascular risks where stimulants are contraindicated or not preferred.

Side Or Adverse Effects

Common side effects in adults: trouble sleeping (insomnia), headache, somnolence, fatigue, nausea, decreased appetite, dry mouth, and constipation.
Common side effects in pediatric patients: somnolence, decreased appetite, fatigue, nausea, vomiting, insomnia, and irritability.
Potential for mood or behavioral changes including anxiety, agitation, irritability, restlessness, and hostility.
Rare but serious allergic reactions such as swelling of the face, lips, tongue, or throat, and hives requiring emergency attention.
Possible increase in suicidal thoughts or behaviors especially during initial treatment and dose adjustments.
Manic episodes characterized by racing thoughts, increased energy, decreased need for sleep, and risk-taking behaviors.
Weight loss or failure to gain weight in pediatric patients necessitates monitoring of growth parameters.
Gastrointestinal disturbances including abdominal pain and dyspepsia reported.
Dry mouth and constipation potentially interfering with patient comfort and requiring supportive care.
Headache frequency may increase, requiring symptom management.
Sleep disturbances including both somnolence and insomnia depending on individual response.
Appetite suppression leading to nutritional concerns especially in children.
Rare cardiovascular side effects including increased heart rate and blood pressure.
Potential for drug-induced liver injury is low but patients with hepatic impairment require monitoring.
Other neuropsychiatric adverse events such as nervousness, dizziness, and mood swings have been reported.

Precautions

Evaluate personal and family history of depression, bipolar disorder, psychosis, and suicidal ideation prior to treatment initiation.
Monitor closely for emergent or worsening suicidal thoughts, behaviors, or mood changes, particularly in the first months of therapy.
Screen and monitor cardiovascular status including heart rate and blood pressure before and during treatment.
Use caution in patients with known heart disease or hypertension; regular monitoring recommended.
Avoid use in patients taking monoamine oxidase inhibitors (MAOIs) or within 14 days of MAOI therapy due to risk of hypertensive crisis.
Initiate therapy with gradual titration to assess tolerability and reduce adverse effects.
Monitor weight and growth in pediatric patients to detect clinically significant weight loss or growth delays.
Exercise caution in patients with hepatic or severe renal impairment; dose adjustments may be necessary.
Advise patients against performing hazardous tasks such as driving until individual response is known due to potential sedation or somnolence.
Assess for potential drug interactions prior to initiating concomitant medications that may impact hepatic metabolism or CNS effects.
Pregnancy: Use only if clearly needed; potential risk to fetus unknown. Advise pregnant women to inform healthcare provider immediately.
Breastfeeding: Unknown if excreted in human milk; weigh benefits versus risks when prescribing to nursing mothers.
Advise patients to disclose all medications, supplements, and herbal products to their healthcare provider.
Instruct patients on symptom reporting for allergic reactions, mood changes, or other side effects.
Regularly reassess treatment efficacy and tolerability; consider drug holidays or dosage adjustment as clinically indicated.

Warnings

Risk of suicidal thoughts and behaviors, especially during the initial months of therapy or during dose changes; close monitoring required.
Possible emergence of manic or hypomanic episodes in patients with bipolar disorder history.
Serious hypersensitivity reactions including anaphylaxis and angioedema have been reported.
Not to be used concomitantly with MAO inhibitors or within 14 days of MAOI discontinuation due to potential fatal interactions.
Potential for increases in blood pressure and heart rate; monitor cardiovascular parameters regularly.
May cause somnolence or fatigue; patients should be advised against operating heavy machinery until effects are known.
Weight loss or failure to gain weight in children necessitates monitoring to avoid nutritional deficiencies or growth retardation.
Use caution in patients with hepatic or renal impairment; impaired clearance may increase adverse effects.
There is a lack of long-term data on effects during pregnancy and breastfeeding; use only if benefits justify risk.
Monitor for new or worsening psychiatric symptoms including irritability, hostility, aggression, and psychosis.
Possibility of drug interaction-related adverse events with certain CNS depressants and serotonergic agents.
Abrupt discontinuation is not well studied; clinical guidance suggests careful tapering in some cases.
Not classified as a controlled substance but potential for misuse cannot be fully excluded; clinical vigilance advised.
Avoid abrupt dose changes to prevent withdrawal or rebound symptoms.
Patients should be informed about signs of serious side effects and instructed to seek immediate medical attention if they occur.

Contraindication

Known hypersensitivity to viloxazine or any components of the formulation.
Use of monoamine oxidase inhibitors (MAOIs) within the past 14 days due to risk of hypertensive crisis.
History of severe allergic reaction to viloxazine or related compounds.
Concomitant use with drugs contraindicated due to interactions such as alosetron, duloxetine, ramelteon, tasimelteon, tizanidine, and theophylline without careful medical supervision.
Patients with diagnosed bipolar disorder not stabilized on appropriate mood stabilizers without psychiatric oversight.
Severe hepatic impairment where metabolism and clearance of viloxazine may be markedly impaired without dose modification.
Patients with severe renal impairment without dose adjustment and monitoring.
Use in patients with history of suicidal ideation or attempts without close clinical monitoring.
Individuals who cannot swallow capsules and refuse administering mixed capsule contents as recommended.
Use in combination with other CNS stimulants for ADHD, unless strictly monitored, to avoid additive adverse effects.

Drug Interactions

Contraindicated with Monoamine Oxidase Inhibitors (MAOIs) such as isocarboxazid, phenelzine, tranylcypromine, due to risk of hypertensive crisis.
Potential pharmacokinetic and pharmacodynamic interactions with duloxetine increasing serotonergic effects and risk of serotonin syndrome.
Interaction with alosetron that may increase risk of adverse CNS and cardiovascular effects.
Tizanidine co-administration may lead to enhanced CNS depressant effects and altered blood pressure control.
Co-administration with ramelteon or tasimelteon may affect CNS depressant properties and sedation levels.
Possible altered clearance or toxicity when used with theophylline due to competing metabolic pathways.
Caution advised with other drugs that modify norepinephrine or serotonin neurotransmission to avoid additive adverse effects.
No significant CYP450 mediated drug interactions identified; however, careful monitoring recommended when used with other CNS active agents.
Concurrent use with alcohol or sedatives may potentiate CNS depression.
Interactions with antihypertensive medications may require dose adjustments due to viloxazine's effects on blood pressure.
No interaction with common ADHD stimulant medications established, but combined use should be approached cautiously.
Potential interaction with drugs affecting GI motility or absorption, although clinically relevant interactions are rare.
Patients should inform healthcare providers about all prescription, over-the-counter medications, and herbal supplements.
Use with serotonergic agents may increase risk of serotonin syndrome; monitor for symptoms such as confusion, agitation, and hyperthermia.
Clinically significant interactions remain limited but non-negligible; ongoing pharmacovigilance warranted.

Preparations Of The Drug

Viloxazine extended-release capsules available in 100 mg, 150 mg, and 200 mg strengths.
Inactive ingredients include ammonium hydroxide, black iron oxide, butyl alcohol, corn starch, ethylcellulose, multiple FD&C colorants (Blue #1, Red #28, Yellow #5, Yellow #6, Yellow #10), gelatin, hypromellose, isopropyl alcohol, lactose monohydrate, medium chain triglycerides, oleic acid, polyethylene glycol, potassium hydroxide, propylene glycol, shellac, strong ammonia solution, sucrose, talc, triacetin, and titanium dioxide.
Extended-release formulation designed to provide 24-hour therapeutic drug levels with once-daily dosing.
Capsules intended to be swallowed whole but can be opened and contents mixed with applesauce for patients with swallowing difficulties.
Manufactured and distributed by Catalent Pharma Solutions, LLC and Supernus Pharmaceuticals, Inc.
Packaged for room temperature storage between 20°C to 25°C (68°F to 77°F).
Not formulated as a controlled substance, facilitating prescription without stringent regulatory controls.
Available prescription-only via healthcare providers familiar with ADHD management.
Non-stimulant medication option with lower abuse potential compared to amphetamine and methylphenidate-based therapies.
Formulation includes multiple colorants and excipients to ensure capsule stability and controlled release.