Tomoxetina

Uses

Attention deficit hyperactivity disorder (ADHD).

Tomoxetina is also used to associated treatment for these conditions: Attention Deficit Hyperactivity Disorder (ADHD)

How Tomoxetina works

Tomoxetina is known to be a potent and selective inhibitor of the norepinephrine transporter (NET), which prevents cellular reuptake of norepinephrine throughout the brain, which is thought to improve the symptoms of ADHD. More recently, positron emission tomography (PET) imaging studies in rhesus monkeys have shown that atomoxetine also binds to the serotonin transporter (SERT), and blocks the N-methyl-d-aspartate (NMDA) receptor, indicating a role for the glutamatergic system in the pathophysiology of ADHD.

Dosage

Tomoxetina dosage

Adult & adolescents->70 kg:

• Initially: 40 mg/day for at least 7 days.
• Maintenance: 80 mg/day.
• Max: 100 mg/day.

Children & adolescents-Up to 70 kg:

• Initially: 0.5 mg/kg/day for at least 7 days.
• Maintenance: 1.2 mg/kg/day.
• Max: 1.8 mg/kg/day.

Side Effects

Decreased appetite; headache; nausea; increased BP & heart rate; Insomnia; dry mouth in adults; Somnolence; abdominal pain; vomiting in children.

Toxicity

There is limited clinical trial experience with atomoxetine overdose. During postmarketing, there have been fatalities reported involving a mixed ingestion overdose of atomoxetine capsules and at least one other drug. There have been no reports of death involving overdose of atomoxetine capsules alone, including intentional overdoses at amounts up to 1400 mg. In some cases of overdose involving atomoxetine, seizures have been reported. The most commonly reported symptoms accompanying acute and chronic overdoses of atomoxetine capsules were gastrointestinal symptoms, somnolence, dizziness, tremor, and abnormal behavior. Hyperactivity and agitation have also been reported. Signs and symptoms consistent with mild to moderate sympathetic nervous system activation (e.g., tachycardia, blood pressure increased, mydriasis, dry mouth) have also been observed. Most events were mild to moderate. Less commonly, there have been reports of QT prolongation and mental changes, including disorientation and hallucinations. If symptoms of overdose are suspected, a Certified Poison Control Center should be consulted for up to date guidance and advice. Because atomoxetine is highly protein-bound, dialysis is not likely to be useful in the treatment of overdose.

Precaution

Tomoxetina should be used with caution in patients with a history of seizures. Tomoxetina can affect heart rate and blood pressure. It is recommended that the heart rate and blood pressure be measured before treatment is started and periodically during treatment to detect possible clinically important increases. Most patients taking Tomoxetina experience a modest increase in heart rate

Interaction

Albuterol, CYP2D6 inhibitors & antihypertensive agents interact with Tomoxetina.

Food Interaction

• Take with or without food.

Tomoxetina Hypertension interaction

[Major] CNS stimulant medications have shown to increase blood pressure, and their use might be contraindicated in patients with severe hypertension.

Caution should be used when administering to patients with preexisting high blood pressure and other cardiovascular conditions.

All patients under treatment should be regularly monitored for changes in blood pressure and heart rate.

Tomoxetina Drug Interaction

Major: escitalopram, escitalopram, fluoxetine, fluoxetineModerate: lisdexamfetamine, lisdexamfetamineUnknown: amphetamine / dextroamphetamine, amphetamine / dextroamphetamine, amphetamine / dextroamphetamine, amphetamine / dextroamphetamine, omega-3 polyunsaturated fatty acids, omega-3 polyunsaturated fatty acids, lamotrigine, lamotrigine, cyanocobalamin, cyanocobalamin, cholecalciferol, cholecalciferol, cetirizine, cetirizine

Tomoxetina Disease Interaction

Major: narrow angle glaucoma, cardiac disease, glaucoma, hypertension, liver disease, psychiatric disordersModerate: bipolar disorders, psychotic disorders, renal dysfunction, seizure disordersMinor: urinary retention

Volume of Distribution

The reported volume of distribution of oral atomoxetine was 1.6-2.6 L/kg. The steady-state volume of distribution of intravenous atomoxetine was approximately 0.85 L/kg.

Elimination Route

The pharmacokinetic profile of atomoxetine is highly dependent on cytochrome P450 2D6 genetic polymorphisms of the individual. A large fraction of the population (up to 10% of Caucasians and 2% of people of African descent and 1% of Asians) are poor metabolizers (PMs) of CYP2D6 metabolized drugs. These individuals have reduced activity in this pathway resulting in 10-fold higher AUCs, 5-fold higher peak plasma concentrations, and slower elimination (plasma half-life of 21.6 hours) of atomoxetine compared with people with normal CYP2D6 activity.

Tomoxetina is rapidly absorbed after oral administration, with absolute bioavailability of about 63% in extensive metabolizers (EMs) and 94% in poor metabolizers (PMs). Mean maximal plasma concentrations (Cmax) are reached approximately 1 to 2 hours after dosing with a maximal concentration of 350 ng/ml with an AUC of 2 mcg.h/ml.

Half Life

The reported half-life depends on the CYP2D6 genetic polymorphisms of the individual and can range from 3 to 5.6 hours.

Clearance

The clearance rate of atomoxetine depends the CYP2D6 genetic polymorphisms of the individual and can range of 0.27-0.67 L.h/kg.

Elimination Route

Tomoxetina is excreted primarily as 4-hydroxyatomoxetine-O-glucuronide, mainly in the urine (greater than 80% of the dose) and to a lesser extent in the feces (less than 17% of the dose). Only a small fraction (less than 3%) of the atomoxetine dose is excreted as unchanged atomoxetine, indicating extensive biotransformation.

Pregnancy & Breastfeeding use

Pregnancy Category C. Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal or other) and there are no studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the fetus.

Contraindication

• Hypersensitivity to Tomoxetina
• Concomitant use with Monoamine oxidase inhibitors (MAOIs).
• Narrow-angle glaucoma.
• Severe cardiovascular or cerebrovascular disorders.
• History of pheochromocytoma.

Special Warning

Pediatric use: The pharmacokinetics of Tomoxetina have not been evaluated in children under 6 years of age.

Acute Overdose

The most commonly reported gastrointestinal symptoms including somnolence, dizziness, tremor, and abnormal behaviour. Hyperactivity and agitation have also been reported. Signs and symptoms consistent with mild to moderate sympatheticnervous system activation (e.g. tachycardia, blood pressure increased, mydriasis, dry mouth) were also observed. Most events were mild to moderate. In some cases of overdose involving Tomoxetina, seizures and very rarely QT prolongation have been reported. There is limited clinical trial experience with Tomoxetina overdose. No fatal overdoses occurred in clinical trials.

Storage Condition

Store in a cool and dry place, protected from light and moisture.

Innovators Monograph

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