Atomoxetine: prescribing information – dosing, contraindications, interactions, side effects

For healthcare professionals

Indications and usage

1.1 Attention-Deficit/Hyperactivity Disorder (ADHD)

Atomoxetine capsules are indicated for the treatment of Attention-Deficit/Hyperactivity Disorder (ADHD).

The efficacy of atomoxetine capsules was established in seven clinical trials in outpatients with ADHD: four 6 to 9-week trials in pediatric patients (ages 6 to 18), two 10-week trial in adults, and one maintenance trial in pediatrics (ages 6 to 15) [ see Clinical Studies ( 14) ].

1.2 Diagnostic Considerations

A diagnosis of ADHD (DSM-IV) implies the presence of hyperactive-impulsive or inattentive symptoms that cause impairment and that were present before age 7 years. The symptoms must be persistent, must be more severe than is typically observed in individuals at a comparable level of development, must cause clinically significant impairment, e.g., in social, academic, or occupational functioning, and must be present in 2 or more settings, e.g., school (or work) and at home. The symptoms must not be better accounted for by another mental disorder.

The specific etiology of ADHD is unknown, and there is no single diagnostic test. Adequate diagnosis requires the use not only of medical but also of special psychological, educational, and social resources. Learning may or may not be impaired. The diagnosis must be based upon a complete history and evaluation of the patient and not solely on the presence of the required number of DSM-IV characteristics.

For the Inattentive Type, at least 6 of the following symptoms must have persisted for at least 6 months: lack of attention to details/careless mistakes, lack of sustained attention, poor listener, failure to follow through on tasks, poor organization, avoids tasks requiring sustained mental effort, loses things, easily distracted, forgetful. For the Hyperactive-Impulsive Type, at least 6 of the following symptoms must have persisted for at least 6 months: fidgeting/squirming, leaving seat, inappropriate running/climbing, difficulty with quiet activities, “on the go,” excessive talking, blurting answers, can’t wait turn, intrusive. For a Combined Type diagnosis, both inattentive and hyperactive-impulsive criteria must be met.

1.3 Need for Comprehensive Treatment Program

Atomoxetine capsules are indicated as an integral part of a total treatment program for ADHD that may include other measures (psychological, educational, social) for patients with this syndrome. Drug treatment may not be indicated for all patients with this syndrome. Drug treatment is not intended for use in the patient who exhibits symptoms secondary to environmental factors and/or other primary psychiatric disorders, including psychosis. Appropriate educational placement is essential in children and adolescents with this diagnosis and psychosocial intervention is often helpful. When remedial measures alone are insufficient, the decision to prescribe drug treatment medication will depend upon the physician’s assessment of the chronicity and severity of the patient’s symptoms.

Dosage and administration

2.1 Acute Treatment

Dosing of children and adolescents up to 70 kg body weight — Atomoxetine capsules should be initiated at a total daily dose of approximately 0.5 mg/kg and increased after a minimum of 3 days to a target total daily dose of approximately 1.2 mg/kg administered either as a single daily dose in the morning or as evenly divided doses in the morning and late afternoon/early evening. No additional benefit has been demonstrated for doses higher than 1.2 mg/kg/day [ see Clinical Studies ( 14) ].

The total daily dose in children and adolescents should not exceed 1.4 mg/kg or 100 mg, whichever is less.

Dosing of children and adolescents over 70 kg body weight and adults — Atomoxetine capsules should be initiated at a total daily dose of 40 mg and increased after a minimum of 3 days to a target total daily dose of approximately 80 mg administered either as a single daily dose in the morning or as evenly divided doses in the morning and late afternoon/early evening. After 2 to 4 additional weeks, the dose may be increased to a maximum of 100 mg in patients who have not achieved an optimal response. There are no data that support increased effectiveness at higher doses [ see Clinical Studies ( 14) ].

The maximum recommended total daily dose in children and adolescents over 70 kg and adults is 100 mg.

2.2 Maintenance/Extended Treatment

It is generally agreed that pharmacological treatment of ADHD may be needed for extended periods. The benefit of maintaining pediatric patients (ages 6 to 15 years) with ADHD on atomoxetine capsules after achieving a response in a dose range of 1.2 to 1.8 mg/kg/day was demonstrated in a controlled trial. Patients assigned to atomoxetine capsules in the maintenance phase were generally continued on the same dose used to achieve a response in the open label phase. The physician who elects to use atomoxetine capsules for extended periods should periodically reevaluate the long-term usefulness of the drug for the individual patient [ see Clinical Studies ( 14.1) ].

2.3 General Dosing Information

Atomoxetine capsules may be taken with or without food.

Atomoxetine capsules can be discontinued without being tapered.

Atomoxetine capsules are not intended to be opened, they should be taken whole [ see Patient Counseling Information ( 17.6) ].

The safety of single doses over 120 mg and total daily doses above 150 mg have not been systematically evaluated.

2.4 Dosing in Specific Populations

Dosing adjustment for hepatically impaired patients — For those ADHD patients who have hepatic insufficiency (HI), dosage adjustment is recommended as follows: For patients with moderate HI (Child-Pugh Class B), initial and target doses should be reduced to 50% of the normal dose (for patients without HI). For patients with severe HI (Child-Pugh Class C), initial dose and target doses should be reduced to 25% of normal [ see Use in Specific Populations ( 8.6) ].

Dosing adjustment for use with a strong CYP2D6 inhibitor or in patients who are known to be CYP2D6 PMs — In children and adolescents up to 70 kg body weight administered strong CYP2D6 inhibitors, e.g., paroxetine, fluoxetine, and quinidine, or in patients who are known to be CYP2D6 PMs, atomoxetine capsules should be initiated at 0.5 mg/kg/day and only increased to the usual target dose of 1.2 mg/kg/day if symptoms fail to improve after 4 weeks and the initial dose is well tolerated.

In children and adolescents over 70 kg body weight and adults administered strong CYP2D6 inhibitors, e.g., paroxetine, fluoxetine, and quinidine, atomoxetine capsules should be initiated at 40 mg/day and only increased to the usual target dose of 80 mg/day if symptoms fail to improve after 4 weeks and the initial dose is well tolerated.

Dosage forms and strengths

Each capsule contains atomoxetine HCl, USP equivalent to 10 mg (white opaque, white opaque), 18 mg (yellow opaque, white opaque), 25 mg (aqua blue opaque, white opaque), 40 mg (aqua blue opaque, aqua blue opaque), 60 mg (aqua blue opaque, yellow opaque), 80 mg (brownish-yellow opaque, white opaque), or 100 mg (brownish-yellow opaque, brownish-yellow opaque) of atomoxetine.

Contraindications

4.1 Hypersensitivity

Atomoxetine capsules are contraindicated in patients known to be hypersensitive to atomoxetine or other constituents of the product [ see Warnings and Precautions ( 5.8) ].

4.2 Monoamine Oxidase Inhibitors (MAOI)

Atomoxetine capsules should not be taken with an MAOI, or within 2 weeks after discontinuing an MAOI. Treatment with an MAOI should not be initiated within 2 weeks after discontinuing atomoxetine capsules. With other drugs that affect brain monoamine concentrations, there have been reports of serious, sometimes fatal reactions (including hyperthermia, rigidity, myoclonus, autonomic instability with possible rapid fluctuations of vital signs, and mental status changes that include extreme agitation progressing to delirium and coma) when taken in combination with an MAOI. Some cases presented with features resembling neuroleptic malignant syndrome. Such reactions may occur when these drugs are given concurrently or in close proximity [ see Drug Interactions ( 7.1) ].

4.3 Narrow Angle Glaucoma

In clinical trials, atomoxetine capsule use was associated with an increased risk of mydriasis and therefore its use is not recommended in patients with narrow angle glaucoma.

4.4 Pheochromocytoma

Serious reactions, including elevated blood pressure and tachyarrhythmia, have been reported in patients with pheochromocytoma or a history of pheochromocytoma who received atomoxetine capsules. Therefore, atomoxetine capsules should not be taken by patients with pheochromocytoma or a history of pheochromocytoma .

4.5 Severe Cardiovascular Disorders

Atomoxetine capsules should not be used in patients with severe cardiac or vascular disorders whose condition would be expected to deteriorate if they experience increases in blood pressure or heart rate that could be clinically important (for example, 15 to 20 mm Hg in blood pressure or 20 beats per minute in heart rate) [s ee Warnings and Precautions ( 5.4)].

Adverse reactions

6.1 Clinical Trials Experience

Atomoxetine hydrochloride was administered to 5382 children or adolescent patients with ADHD and 1007 adults with ADHD in clinical studies. During the ADHD clinical trials, 1625 children and adolescent patients were treated for longer than 1 year and 2529 children and adolescent patients were treated for over 6 months.

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Child and Adolescent Clinical Trials

Reasons for discontinuation of treatment due to adverse reactions in child and adolescent clinical trials — In acute child and adolescent placebo-controlled trials, 3.0% (48/1613) of atomoxetine subjects and 1.4% (13/945) placebo subjects discontinued for adverse reactions. For all studies, (including open-label and long-term studies), 6.3% of extensive metabolizer (EM) patients and 11.2% of poor metabolizer (PM) patients discontinued because of an adverse reaction. Among atomoxetine hydrochloride-treated patients, irritability (0.3%, N = 5); somnolence (0.3%, N = 5); aggression (0.2%, N = 4); nausea (0.2%, N = 4); vomiting (0.2%, N = 4); abdominal pain (0.2%, N = 4); constipation (0.1%, N = 2); fatigue (0.1%, N = 2); feeling abnormal (0.1%, N = 2); and headache (0.1%, N = 2) were the reasons for discontinuation reported by more than 1 patient.

Seizures — Atomoxetine hydrochloride has not been systematically evaluated in pediatric patients with seizure disorder as these patients were excluded from clinical studies during the product’s premarket testing. In the clinical development program, seizures were reported in 0.2% (12/5073) of children whose average age was 10 years (range 6 to 16 years). In these clinical trials, the seizure risk among poor metabolizers was 0.3% (1/293) compared to 0.2% (11/4741) for extensive metabolizers.

Commonly observed adverse reactions in acute child and adolescent, placebo-controlled trials — Commonly observed adverse reactions associated with the use of atomoxetine hydrochloride (incidence of 2% or greater) and not observed at an equivalent incidence among placebo-treated patients (atomoxetine hydrochloride incidence greater than placebo) are listed in Table 2. Results were similar in the BID and the QD trial except as shown in Table 3, which shows both BID and QD results for selected adverse reactions based on statistically significant Breslow-Day tests. The most commonly observed adverse reactions in patients treated with atomoxetine hydrochloride (incidence of 5% or greater and at least twice the incidence in placebo patients, for either BID or QD dosing) were: nausea, vomiting, fatigue, decreased appetite, abdominal pain, and somnolence ( see Tables 2 and 3).

Additional data from ADHD clinical trials (controlled and uncontrolled) has shown that approximately 5 to 10% of pediatric patients experienced potentially clinically important changes in heart rate (≥ 20 beats per min) or blood pressure (≥ 15 to 20 mm Hg) [ see Contraindications ( 4) and Warnings and Precautions ( 5) ].

Table 2: Common Treatment-Emergent Adverse Reactions Associated with the Use of Atomoxetine Hydrochloride in Acute (up to 18 Weeks) Child and Adolescent Trials
Adverse Reaction a | Percentage of Patients Reporting Reaction
| Atomoxetine Hydrochloride (N = 1597) | Placebo (N = 934)
Gastrointestinal Disorders | |
Abdominal pain b | 18 | 10
Vomiting | 11 | 6
Nausea | 10 | 5
General Disorders and Administration Site Conditions | |
Fatigue | 8 | 3
Irritability | 6 | 3
Therapeutic response unexpected | 2 | 1
Investigations | |
Weight decreased | 3 | 0
Metabolism and Nutritional Disorders | |
Decreased appetite | 16 | 4
Anorexia | 3 | 1
Nervous System Disorders | |
Headache | 19 | 15
Somnolence c | 11 | 4
Dizziness | 5 | 2
Skin and Subcutaneous Tissue Disorders | |
Rash | 2 | 1
a Reactions reported by at least 2% of patients treated with atomoxetine, and greater than placebo. The following reactions did not meet this criterion but were reported by more atomoxetine-treated patients than placebo-treated patients and are possibly related to atomoxetine treatment: blood pressure increased, early morning awakening (terminal insomnia), flushing, mydriasis, sinus tachycardia, asthenia, palpitations, mood swings, constipation, and dyspepsia. The following reactions were reported by at least 2% of patients treated with atomoxetine, and equal to or less than placebo: pharyngolaryngeal pain, insomnia (insomnia includes the terms, insomnia, initial insomnia, middle insomnia). The following reaction did not meet this criterion but shows a statistically significant dose relationship: pruritus. b Abdominal pain includes the terms: abdominal pain upper, abdominal pain, stomach discomfort, abdominal discomfort, epigastric discomfort. c Somnolence includes the terms: sedation, somnolence.

Table 3: Common Treatment-Emergent Adverse Reactions Associated with the Use of Atomoxetine Hydrochloride in Acute (up to 18 weeks) Child and Adolescent Trials
Adverse Reaction | Percentage of Patients Reporting Reaction from BID Trials | Percentage of Patients Reporting Reaction from QD Trials
| Atomoxetine Hydrochloride (N = 715) | Placebo (N = 434) | Atomoxetine Hydrochloride (N = 882) | Placebo (N = 500)
Gastrointestinal Disorders | | | |
Abdominal pain a | 17 | 13 | 18 | 7
Vomiting | 11 | 8 | 11 | 4
Nausea | 7 | 6 | 13 | 4
Constipation b | 2 | 1 | 1 | 0
General Disorders | | | |
Fatigue | 6 | 4 | 9 | 2
Psychiatric Disorders | | | |
Mood swings c | 2 | 0 | 1 | 1
a Abdominal pain includes the terms: abdominal pain upper, abdominal pain, stomach discomfort, abdominal discomfort, epigastric discomfort. b Constipation didn’t meet the statistical significance on Breslow-Day test but is included in the table because of pharmacologic plausibility. c Mood swings didn’t meet the statistical significance on Breslow-Day test at 0.05 level but p-value was < 0.1 (trend).

The following adverse reactions occurred in at least 2% of child and adolescent CYP2D6 PM patients and were statistically significantly more frequent in PM patients compared with CYP2D6 EM patients: insomnia (11% of PMs, 6% of EMs); weight decreased (7% of PMs, 4% of EMs); constipation (7% of PMs, 4% of EMs); depression¹ (7% of PMs, 4% of EMs); tremor (5% of PMs, 1% of EMs); excoriation (4% of PMs, 2% of EMs); middle insomnia (3% of PMs, 1% of EMs); conjunctivitis (3% of PMs, 1% of EMs); syncope (3% of PMs, 1% of EMs); early morning awakening (2% of PMs, 1% of EMs); mydriasis (2% of PMs, 1% of EMs); sedation (4% of PMs, 2% of EMs).

¹ Depression includes the following terms: depression, major depression, depressive symptoms, depressed mood, dysphoria.

Adult Clinical Trials

Reasons for discontinuation of treatment due to adverse reactions in acute adult placebo-controlled trials — In the acute adult placebo-controlled trials, 11.3% (61/541) atomoxetine subjects and 3.0% (12/405) placebo subjects discontinued for adverse reactions. Among atomoxetine hydrochloride-treated patients, insomnia (0.9%, N = 5); nausea (0.9%, N = 5); chest pain (0.6%, N = 3); fatigue (0.6%, N = 3); anxiety (0.4%, N = 2); erectile dysfunction (0.4%, N = 2); mood swings (0.4%, N = 2); nervousness (0.4%, N = 2); palpitations (0.4%, N = 2); and urinary retention (0.4%, N = 2) were the reasons for discontinuation reported by more than 1 patient.

Seizures — Atomoxetine hydrochloride has not been systematically evaluated in adult patients with a seizure disorder as these patients were excluded from clinical studies during the product’s premarket testing. In the clinical development program, seizures were reported on 0.1% (1/748) of adult patients. In these clinical trials, no poor metabolizers (0/43) reported seizures compared to 0.1% (1/705) for extensive metabolizers.

Commonly observed adverse reactions in acute adult placebo-controlled trials — Commonly observed adverse reactions associated with the use of atomoxetine hydrochloride (incidence of 2% or greater) and not observed at an equivalent incidence among placebo-treated patients (atomoxetine hydrochloride incidence greater than placebo) are listed in Table 4. The most commonly observed adverse reactions in patients treated with atomoxetine hydrochloride (incidence of 5% or greater and at least twice the incidence in placebo patients) were: constipation, dry mouth, nausea, decreased appetite, dizziness, erectile dysfunction, and urinary hesitation ( see Table 4).

Additional data from ADHD clinical trials (controlled and uncontrolled) has shown that approximately 5 to 10% of adult patients experienced potentially clinically important changes in heart rate (≥ 20 beats per min) or blood pressure (≥ 15 to 20 mm Hg) [ see Contraindications ( 4) and Warnings and Precautions ( 5) ].

The following adverse events occurred in at least 2% of adult CYP2D6 poor metaboliser (PM) patients and were statistically significantly more frequent in PM patients compared to CYP2D6 extensive metaboliser (EM) patients: vision blurred (4% of PMs, 1% of EMs); dry mouth (35% of PMs, 17% of EMs); constipation (11% of PMs, 7% of EMs); feeling jittery (5% of PMs, 2% of EMs); decreased appetite (23% of PMs, 15% of EMs); tremor (5% of PMs, 1% of EMs); insomnia (19% of PMs, 11% of EMs); sleep disorder (7% of PMs, 3% of EMs); middle insomnia (5% of PMs, 3% of EMs); terminal insomnia (3% of PMs, 1% of EMs); urinary retention (6% of PMs, 1% of EMs); erectile dysfunction (21% of PMs, 9% of EMs); ejaculation disorder (6% of PMs, 2% of EMs); hyperhidrosis (15% of PMs, 7% of EMs); peripheral coldness (3% of PMs, 1% of EMs).

Male and female sexual dysfunction — Atomoxetine appears to impair sexual function in some patients. Changes in sexual desire, sexual performance, and sexual satisfaction are not well assessed in most clinical trials because they need special attention and because patients and physicians may be reluctant to discuss them. Accordingly, estimates of the incidence of untoward sexual experience and performance cited in product labeling are likely to underestimate the actual incidence. Table 4 above displays the incidence of sexual side effects reported by at least 2% of adult patients taking atomoxetine hydrochloride in placebo-controlled trials.

There are no adequate and well-controlled studies examining sexual dysfunction with atomoxetine hydrochloride treatment. While it is difficult to know the precise risk of sexual dysfunction associated with the use of atomoxetine hydrochloride, physicians should routinely inquire about such possible side effects.

6.2 Postmarketing Spontaneous Reports

The following adverse reactions have been identified during post approval use of atomoxetine hydrochloride. Unless otherwise specified, these adverse reactions have occurred in adults and children and adolescents. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Cardiovascular system — QT prolongation, syncope.

Peripheral vascular effects — Raynaud’s phenomenon.

General disorders and administration site conditions — Lethargy.

Musculoskeletal system — Rhabdomyolysis.

Nervous system disorders — Hypoaesthesia; paraesthesia in children and adolescents; sensory disturbances; tics.

Psychiatric disorders — Depression and depressed mood; anxiety, libido changes.

Seizures — Seizures have been reported in the postmarketing period. The postmarketing seizure cases include patients with pre-existing seizure disorders and those with identified risk factors for seizures, as well as patients with neither a history of nor identified risk factors for seizures. The exact relationship between atomoxetine hydrochloride and seizures is difficult to evaluate due to uncertainty about the background risk of seizures in ADHD patients.

Skin and subcutaneous tissue disorders — Alopecia, hyperhidrosis.

Urogenital system — Male pelvic pain; urinary hesitation in children and adolescents; urinary retention in children and adolescents.

To report SUSPECTED ADVERSE REACTIONS contact AvKARE at 1-855-361-3993; email drugsafety@avkare.com; or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Warnings and precautions

5.1 Suicidal Ideation

Atomoxetine hydrochloride increased the risk of suicidal ideation in short-term studies in children and adolescents with Attention-Deficit/Hyperactivity Disorder (ADHD). Pooled analyses of short-term (6 to 18 weeks) placebo-controlled trials of atomoxetine hydrochloride in children and adolescents have revealed a greater risk of suicidal ideation early during treatment in those receiving atomoxetine hydrochloride. There were a total of 12 trials (11 in ADHD and 1 in enuresis) involving over 2200 patients (including 1357 patients receiving atomoxetine hydrochloride and 851 receiving placebo). The average risk of suicidal ideation in patients receiving atomoxetine hydrochloride was 0.4% (5/1357 patients), compared to none in placebo-treated patients. There was 1 suicide attempt among these approximately 2200 patients, occurring in a patient treated with atomoxetine hydrochloride. No suicides occurred in these trials. All reactions occurred in children 12 years of age or younger. All reactions occurred during the first month of treatment. It is unknown whether the risk of suicidal ideation in pediatric patients extends to longer-term use. A similar analysis in adult patients treated with atomoxetine hydrochloride for either ADHD or major depressive disorder (MDD) did not reveal an increased risk of suicidal ideation or behavior in association with the use of atomoxetine hydrochloride.

All pediatric patients being treated with atomoxetine hydrochloride should be monitored appropriately and observed closely for clinical worsening, suicidality, and unusual changes in behavior, especially during the initial few months of a course of drug therapy, or at times of dose changes, either increases or decreases.

The following symptoms have been reported with atomoxetine hydrochloride: anxiety, agitation, panic attacks, insomnia, irritability, hostility, aggressiveness, impulsivity, akathisia (psychomotor restlessness), hypomania and mania. Although a causal link between the emergence of such symptoms and the emergence of suicidal impulses has not been established, there is a concern that such symptoms may represent precursors to emerging suicidality. Thus, patients being treated with atomoxetine hydrochloride should be observed for the emergence of such symptoms.

Consideration should be given to changing the therapeutic regimen, including possibly discontinuing the medication, in patients who are experiencing emergent suicidality or symptoms that might be precursors to emerging suicidality, especially if these symptoms are severe or abrupt in onset, or were not part of the patient’s presenting symptoms.

Families and caregivers of pediatric patients being treated with atomoxetine hydrochloride should be alerted about the need to monitor patients for the emergence of agitation, irritability, unusual changes in behavior, and the other symptoms described above, as well as the emergence of suicidality, and to report such symptoms immediately to healthcare providers. Such monitoring should include daily observation by families and caregivers.

5.2 Severe Liver Injury

Postmarketing reports indicate that atomoxetine hydrochloride can cause severe liver injury. Although no evidence of liver injury was detected in clinical trials of about 6000 patients, there have been rare cases of clinically significant liver injury that were considered probably or possibly related to atomoxetine hydrochloride use in postmarketing experience. Rare cases of liver failure have also been reported, including a case that resulted in a liver transplant. Because of probable underreporting, it is impossible to provide an accurate estimate of the true incidence of these reactions. Reported cases of liver injury occurred within 120 days of initiation of atomoxetine in the majority of cases and some patients presented with markedly elevated liver enzymes [> 20 X upper limit of normal (ULN)], and jaundice with significantly elevated bilirubin levels (> 2 X ULN), followed by recovery upon atomoxetine discontinuation. In one patient, liver injury, manifested by elevated hepatic enzymes up to 40 X ULN and jaundice with bilirubin up to 12 X ULN, recurred upon rechallenge, and was followed by recovery upon drug discontinuation, providing evidence that atomoxetine hydrochloride likely caused the liver injury. Such reactions may occur several months after therapy is started, but laboratory abnormalities may continue to worsen for several weeks after drug is stopped. The patient described above recovered from his liver injury, and did not require a liver transplant.

Atomoxetine hydrochloride should be discontinued in patients with jaundice or laboratory evidence of liver injury, and should not be restarted. Laboratory testing to determine liver enzyme levels should be done upon the first symptom or sign of liver dysfunction (e.g., pruritus, dark urine, jaundice, right upper quadrant tenderness, or unexplained “flu like” symptoms) [ see Warnings and Precautions ( 5.12); Patient Counseling Information ( 17.3) ].

5.3 Serious Cardiovascular Events

Sudden Death and Pre-existing Structural Cardiac Abnormalities or Other Serious Heart Problems

Children and Adolescents — Sudden death has been reported in association with atomoxetine treatment at usual doses in children and adolescents with structural cardiac abnormalities or other serious heart problems. Although some serious heart problems alone carry an increased risk of sudden death, atomoxetine generally should not be used in children or adolescents with known serious structural cardiac abnormalities, cardiomyopathy, serious heart rhythm abnormalities, or other serious cardiac problems that may place them at increased vulnerability to the noradrenergic effects of atomoxetine.

Adults — Sudden deaths, stroke, and myocardial infarction have been reported in adults taking atomoxetine at usual doses for ADHD. Although the role of atomoxetine in these adult cases is also unknown, adults have a greater likelihood than children of having serious structural cardiac abnormalities, cardiomyopathy, serious heart rhythm abnormalities, coronary artery disease, or other serious cardiac problems. Consideration should be given to not treating adults with clinically significant cardiac abnormalities.

Assessing Cardiovascular Status in Patients being Treated with Atomoxetine

Children, adolescents, or adults who are being considered for treatment with atomoxetine should have a careful history (including assessment for a family history of sudden death or ventricular arrhythmia) and physical exam to assess for the presence of cardiac disease, and should receive further cardiac evaluation if findings suggest such disease (e.g., electrocardiogram and echocardiogram). Patients who develop symptoms such as exertional chest pain, unexplained syncope, or other symptoms suggestive of cardiac disease during atomoxetine treatment should undergo a prompt cardiac evaluation.

5.4 Effects on Blood Pressure and Heart Rate

Atomoxetine hydrochloride should be used with caution in patients whose underlying medical conditions could be worsened by increases in blood pressure or heart rate such as certain patients with hypertension, tachycardia, or cardiovascular or cerebrovascular disease. It should not be used in patients with severe cardiac or vascular disorders whose condition would be expected to deteriorate if they experienced clinically important increases in blood pressure or heart rate [ see Contraindications ( 4.5) ]. Pulse and blood pressure should be measured at baseline, following atomoxetine hydrochloride dose increases, and periodically while on therapy to detect possible clinically important increases.

The following table provides short-term, placebo-controlled clinical trial data for the proportions of patients having an increase in: diastolic blood pressure ≥ 15 mm Hg; systolic blood pressure ≥ 20 mm Hg; heart rate greater than or equal to 20 bpm, in both the pediatric and adult populations ( see Table 1).

Table 1 a
| Pediatric Acute Placebo-Controlled | Adult Acute Placebo-Controlled
Maximum b | Endpoint | Maximum b | Endpoint
Atomoxetine | Placebo | Atomoxetine | Placebo | Atomoxetine | Placebo | Atomoxetine | Placebo
% | % | % | % | % | % | % | %
DBP (≥ 15 mm Hg) | 21.5 | 14.1 | 9.3 | 4.8 | 12.6 | 8.7 | 4.8 | 3.5
SBP (≥ 20 mm Hg) | 12.5 | 8.7 | 4.9 | 3.3 | 12.4 | 7.8 | 4.2 | 3.2
HR (≥ 20 bpm) | 23.4 | 11.5 | 12.2 | 3.8 | 22.4 | 8.3 | 10.2 | 2.0
a Abbreviations: bpm = beats per minute; DBP = diastolic blood pressure; HR = heart rate; mm Hg = millimeters mercury; SBP = systolic blood pressure. b Proportion of patients meeting threshold at any one time during clinical trial.

In placebo-controlled registration studies involving pediatric patients, tachycardia was identified as an adverse event for 0.3% (5/1597) of these atomoxetine hydrochloride patients compared with 0% (0/934) of placebo patients. The mean heart rate increase in extensive metabolizer (EM) patients was 5.0 beats/minute, and in poor metabolizer (PM) patients 9.4 beats/minute.

In adult clinical trials where EM/PM status was available, the mean heart rate increase in PM patients was significantly higher than in EM patients (11 beats/minute versus 7.5 beats/minute). The heart rate effects could be clinically important in some PM patients.

In placebo-controlled registration studies involving adult patients, tachycardia was identified as an adverse event for 1.5% (8/540) of atomoxetine hydrochloride patients compared with 0.5% (2/402) of placebo patients.

In adult clinical trials where EM/PM status was available, the mean change from baseline in diastolic blood pressure in PM patients was higher than in EM patients (4.21 versus 2.13 mm Hg) as was the mean change from baseline in systolic blood pressure (PM: 2.75 versus EM: 2.40 mm Hg). The blood pressure effects could be clinically important in some PM patients.

Orthostatic hypotension and syncope have been reported in patients taking atomoxetine hydrochloride. In child and adolescent registration studies, 0.2% (12/5596) of atomoxetine hydrochloride-treated patients experienced orthostatic hypotension and 0.8% (46/5596) experienced syncope. In short-term child and adolescent registration studies, 1.8% (6/340) of atomoxetine hydrochloride-treated patients experienced orthostatic hypotension compared with 0.5% (1/207) of placebo-treated patients. Syncope was not reported during short-term child and adolescent placebo-controlled ADHD registration studies. Atomoxetine hydrochloride should be used with caution in any condition that may predispose patients to hypotension, or conditions associated with abrupt heart rate or blood pressure changes.

5.5 Emergence of New Psychotic or Manic Symptoms

Treatment emergent psychotic or manic symptoms, e.g., hallucinations, delusional thinking, or mania in children and adolescents without a prior history of psychotic illness or mania can be caused by atomoxetine at usual doses. If such symptoms occur, consideration should be given to a possible causal role of atomoxetine, and discontinuation of treatment should be considered. In a pooled analysis of multiple short-term, placebo-controlled studies, such symptoms occurred in about 0.2% (4 patients with reactions out of 1939 exposed to atomoxetine for several weeks at usual doses) of atomoxetine-treated patients compared to 0 out of 1056 placebo-treated patients.

5.6 Screening Patients for Bipolar Disorder

In general, particular care should be taken in treating ADHD in patients with comorbid bipolar disorder because of concern for possible induction of a mixed/manic episode in patients at risk for bipolar disorder. Whether any of the symptoms described above represent such a conversion is unknown. However, prior to initiating treatment with atomoxetine hydrochloride, patients with comorbid depressive symptoms should be adequately screened to determine if they are at risk for bipolar disorder; such screening should include a detailed psychiatric history, including a family history of suicide, bipolar disorder, and depression.

5.7 Aggressive Behavior or Hostility

Patients beginning treatment for ADHD should be monitored for the appearance or worsening of aggressive behavior or hostility. Aggressive behavior or hostility is often observed in children and adolescents with ADHD. In pediatric short-term controlled clinical trials, 21/1308 (1.6%) of atomoxetine patients versus 9/806 (1.1%) of placebo-treated patients spontaneously reported treatment emergent hostility-related adverse events (overall risk ratio of 1.33 [95% C.I. 0.67 to 2.64 – not statistically significant]). In adult placebo-controlled clinical trials, 6/1697 (0.35%) of atomoxetine patients versus 4/1560 (0.26%) of placebo-treated patients spontaneously reported treatment emergent hostility-related adverse events (overall risk ratio of 1.38 [95% C.I. 0.39 to 4.88 – not statistically significant]). Although this is not conclusive evidence that atomoxetine hydrochloride causes aggressive behavior or hostility, these behaviors were more frequently observed in clinical trials among children, adolescents, and adults treated with atomoxetine hydrochloride compared to placebo.

5.8 Allergic Events

Although uncommon, allergic reactions, including anaphylactic reactions, angioneurotic edema, urticaria, and rash, have been reported in patients taking atomoxetine hydrochloride.

5.9 Effects on Urine Outflow from the Bladder

In adult ADHD controlled trials, the rates of urinary retention (1.7%, 9/540) and urinary hesitation (5.6%, 30/540) were increased among atomoxetine subjects compared with placebo subjects (0%, 0/402; 0.5%, 2/402, respectively). Two adult atomoxetine subjects and no placebo subjects discontinued from controlled clinical trials because of urinary retention. A complaint of urinary retention or urinary hesitancy should be considered potentially related to atomoxetine.

5.10 Priapism

Rare postmarketing cases of priapism, defined as painful and nonpainful penile erection lasting more than 4 hours, have been reported for pediatric and adult patients treated with atomoxetine hydrochloride. The erections resolved in cases in which follow-up information was available, some following discontinuation of atomoxetine hydrochloride. Prompt medical attention is required in the event of suspected priapism.

5.11 Effects on Growth

Data on the long-term effects of atomoxetine hydrochloride on growth come from open-label studies, and weight and height changes are compared to normative population data. In general, the weight and height gain of pediatric patients treated with atomoxetine hydrochloride lags behind that predicted by normative population data for about the first 9 to 12 months of treatment. Subsequently, weight gain rebounds and at about 3 years of treatment, patients treated with atomoxetine hydrochloride have gained 17.9 kg on average, 0.5 kg more than predicted by their baseline data. After about 12 months, gain in height stabilizes, and at 3 years, patients treated with atomoxetine hydrochloride have gained 19.4 cm on average, 0.4 cm less than predicted by their baseline data ( see Figure 1 below).

Figure 1: Mean Weight and Height Percentiles Over Time for Patients with Three Years of Atomoxetine Hydrochloride Treatment

This growth pattern was generally similar regardless of pubertal status at the time of treatment initiation. Patients who were pre-pubertal at the start of treatment (girls ≤ 8 years old, boys ≤ 9 years old) gained an average of 2.1 kg and 1.2 cm less than predicted after three years. Patients who were pubertal (girls > 8 to ≤ 13 years old, boys > 9 to ≤ 14 years old) or late pubertal (girls > 13 years old, boys > 14 years old) had average weight and height gains that were close to or exceeded those predicted after three years of treatment.

Growth followed a similar pattern in both extensive and poor metabolizers (EMs, PMs). PMs treated for at least two years gained an average of 2.4 kg and 1.1 cm less than predicted, while EMs gained an average of 0.2 kg and 0.4 cm less than predicted.

In short-term controlled studies (up to 9 weeks), atomoxetine hydrochloride-treated patients lost an average of 0.4 kg and gained an average of 0.9 cm, compared to a gain of 1.5 kg and 1.1 cm in the placebo-treated patients. In a fixed-dose controlled trial, 1.3%, 7.1%, 19.3%, and 29.1% of patients lost at least 3.5% of their body weight in the placebo, 0.5, 1.2, and 1.8 mg/kg/day dose groups.

Growth should be monitored during treatment with atomoxetine hydrochloride.

5.12 Laboratory Tests

Routine laboratory tests are not required.

CYP2D6 metabolism — Poor metabolizers (PMs) of CYP2D6 have a 10 fold higher AUC and a 5 fold higher peak concentration to a given dose of atomoxetine hydrochloride compared with extensive metabolizers (EMs). Approximately 7% of a Caucasian population are PMs. Laboratory tests are available to identify CYP2D6 PMs. The blood levels in PMs are similar to those attained by taking strong inhibitors of CYP2D6. The higher blood levels in PMs lead to a higher rate of some adverse effects of atomoxetine hydrochloride [ see Adverse Reactions ( 6.1) ].

5.13 Concomitant Use of Potent CYP2D6 Inhibitors or Use in Patients who are known to be CYP2D6 PMs

Atomoxetine is primarily metabolized by the CYP2D6 pathway to 4-hydroxyatomoxetine. Dosage adjustment of atomoxetine hydrochloride may be necessary when coadministered with potent CYP2D6 inhibitors (e.g., paroxetine, fluoxetine, and quinidine) or when administered to CYP2D6 PMs [ see Dosage and Administration ( 2.4) and Drug Interactions ( 7.2) ].

Drug interactions

7.1 Monoamine Oxidase Inhibitors

With other drugs that affect brain monoamine concentrations, there have been reports of serious, sometimes fatal reactions (including hyperthermia, rigidity, myoclonus, autonomic instability with possible rapid fluctuations of vital signs, and mental status changes that include extreme agitation progressing to delirium and coma) when taken in combination with an MAOI. Some cases presented with features resembling neuroleptic malignant syndrome. Such reactions may occur when these drugs are given concurrently or in close proximity [ see Contraindications ( 4.2) ].

7.2 Effect of CYP2D6 Inhibitors on Atomoxetine

In extensive metabolizers (EMs), inhibitors of CYP2D6 (e.g., paroxetine, fluoxetine, and quinidine) increase atomoxetine steady-state plasma concentrations to exposures similar to those observed in poor metabolizers (PMs). In EM individuals treated with paroxetine or fluoxetine, the AUC of atomoxetine is approximately 6 to 8 fold and C ss, max is about 3 to 4 fold greater than atomoxetine alone.

In vitro studies suggest that coadministration of cytochrome P450 inhibitors to PMs will not increase the plasma concentrations of atomoxetine.

7.3 Antihypertensive Drugs and Pressor Agents

Because of possible effects on blood pressure, atomoxetine hydrochloride should be used cautiously with antihypertensive drugs and pressor agents (e.g., dopamine, dobutamine) or other drugs that increase blood pressure.

7.4 Albuterol

Atomoxetine hydrochloride should be administered with caution to patients being treated with systemically-administered (oral or intravenous) albuterol (or other beta ₂ agonists) because the action of albuterol on the cardiovascular system can be potentiated resulting in increases in heart rate and blood pressure. Albuterol (600 mcg iv over 2 hours) induced increases in heart rate and blood pressure. These effects were potentiated by atomoxetine (60 mg BID for 5 days) and were most marked after the initial coadministration of albuterol and atomoxetine. However, these effects on heart rate and blood pressure were not seen in another study after the coadministration with inhaled dose of albuterol (200 to 800 mcg) and atomoxetine (80 mg QD for 5 days) in 21 healthy Asian subjects who were excluded for poor metabolizer status.

7.5 Effect of Atomoxetine on P450 Enzymes

Atomoxetine did not cause clinically important inhibition or induction of cytochrome P450 enzymes, including CYP1A2, CYP3A, CYP2D6, and CYP2C9.

CYP3A Substrate (e.g., Midazolam) — Coadministration of atomoxetine (60 mg BID for 12 days) with midazolam, a model compound for CYP3A4 metabolized drugs (single dose of 5 mg), resulted in 15% increase in AUC of midazolam. No dose adjustment is recommended for drugs metabolized by CYP3A.

CYP2D6 Substrate (e.g., Desipramine) — Coadministration of atomoxetine (40 or 60 mg BID for 13 days) with desipramine, a model compound for CYP2D6 metabolized drugs (single dose of 50 mg), did not alter the pharmacokinetics of desipramine. No dose adjustment is recommended for drugs metabolized by CYP2D6.

7.6 Alcohol

Consumption of ethanol with atomoxetine hydrochloride did not change the intoxicating effects of ethanol.

7.7 Methylphenidate

Coadministration of methylphenidate with atomoxetine hydrochloride did not increase cardiovascular effects beyond those seen with methylphenidate alone.

7.8 Drugs Highly Bound to Plasma Protein

In vitro drug-displacement studies were conducted with atomoxetine and other highly-bound drugs at therapeutic concentrations. Atomoxetine did not affect the binding of warfarin, acetylsalicylic acid, phenytoin, or diazepam to human albumin. Similarly, these compounds did not affect the binding of atomoxetine to human albumin.

7.9 Drugs that Affect Gastric pH

Drugs that elevate gastric pH (magnesium hydroxide/aluminum hydroxide, omeprazole) had no effect on atomoxetine hydrochloride bioavailability.

Pregnancy, breastfeeding, children, older adults

8.1 Pregnancy

Pregnancy Exposure Registry

There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to ADHD medications, including atomoxetine hydrochloride during pregnancy. Healthcare providers are encouraged to register patients by calling the National Pregnancy Registry for ADHD Medications at 1-866-961-2388 or visiting https://womensmentalhealth.org/adhd-medications/.

Risk Summary

Available published studies with atomoxetine use in pregnant women are insufficient to establish a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes.

Some animal reproduction studies of atomoxetine had adverse developmental outcomes. One of 3 studies in pregnant rabbits dosed during organogenesis resulted in decreased live fetuses and an increase in early resorptions, as well as slight increases in the incidences of atypical origin of carotid artery and absent subclavian artery. These effects were observed at plasma levels (AUC) 3 times and 0.4 times the human plasma levels in extensive and poor metabolizers receiving the maximum recommended human dose (MRHD), respectively. In rats dosed prior to mating and during organogenesis a decrease in fetal weight (female only) and an increase in the incidence of incomplete ossification of the vertebral arch in fetuses were observed at a dose approximately 5 times the MRHD on a mg/m² basis. In one of 2 studies in which rats were dosed prior to mating through the periods of organogenesis and lactation, decreased pup weight and decreased pup survival were observed at doses corresponding to 5 to 6 times the MRHD on a mg/m² basis. No adverse fetal effects were seen in pregnant rats dosed during the organogenesis period (see Data).

The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.

Data

Animal Data
Pregnant rabbits were treated with up to 100 mg/kg/day of atomoxetine by gavage throughout the period of organogenesis. At this dose, in 1 of 3 studies, a decrease in live fetuses and an increase in early resorptions was observed. Slight increases in the incidences of atypical origin of carotid artery and absent subclavian artery were observed. These findings were observed at doses that caused slight maternal toxicity. The no-effect dose for these findings was 30 mg/kg/day. The 100 mg/kg dose is approximately 23 times the MRHD on a mg/m² basis; plasma levels (AUC) of atomoxetine at this dose in rabbits are estimated to be 3.3 times (extensive metabolizers) or 0.4 times (poor metabolizers) those in humans receiving the MRHD.

Rats were treated with up to approximately 50 mg/kg/day of atomoxetine (approximately 6 times the MRHD on a mg/m² basis) in the diet from 2 weeks (females) or 10 weeks (males) prior to mating through the periods of organogenesis and lactation. In 1 of 2 studies, decreases in pup weight and pup survival were observed. The decreased pup survival was also seen at 25 mg/kg (but not at 13 mg/kg). In a study in which rats were treated with atomoxetine in the diet from 2 weeks (females) or 10 weeks (males) prior to mating throughout the period of organogenesis, a decrease in fetal weight (female only) and an increase in the incidence of incomplete ossification of the vertebral arch in fetuses were observed at 40 mg/kg/day (approximately 5 times the MRHD on a mg/m² basis) but not at 20 mg/kg/day.

No adverse fetal effects were seen when pregnant rats were treated with up to 150 mg/kg/day (approximately 17 times the MRHD on a mg/m² basis) by gavage throughout the period of organogenesis.

8.2 Lactation

Risk Summary
There are no data on the presence of atomoxetine or its metabolite in human milk, the effects on the breastfed child, or the effects on milk production. Atomoxetine is present in animal milk. When a drug is present in animal milk, it is likely that the drug will be present in human milk.

The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for atomoxetine hydrochloride and any potential adverse effects on the breastfed child from atomoxetine hydrochloride or from the underlying maternal condition.

8.4 Pediatric Use

Anyone considering the use of atomoxetine hydrochloride in a child or adolescent must balance the potential risks with the clinical need [ see Boxed Warning and Warnings and Precautions ( 5.1) ].

The pharmacokinetics of atomoxetine in children and adolescents are similar to those in adults. The safety, efficacy, and pharmacokinetics of atomoxetine hydrochloride in pediatric patients less than 6 years of age have not been evaluated.

A study was conducted in young rats to evaluate the effects of atomoxetine on growth and neurobehavioral and sexual development. Rats were treated with 1, 10, or 50 mg/kg/day (approximately 0.2, 2, and 8 times, respectively, the maximum human dose on a mg/m² basis) of atomoxetine given by gavage from the early postnatal period (Day 10 of age) through adulthood. Slight delays in onset of vaginal patency (all doses) and preputial separation (10 and 50 mg/kg), slight decreases in epididymal weight and sperm number (10 and 50 mg/kg), and a slight decrease in corpora lutea (50 mg/kg) were seen, but there were no effects on fertility or reproductive performance. A slight delay in onset of incisor eruption was seen at 50 mg/kg. A slight increase in motor activity was seen on Day 15 (males at 10 and 50 mg/kg and females at 50 mg/kg) and on Day 30 (females at 50 mg/kg) but not on Day 60 of age. There were no effects on learning and memory tests. The significance of these findings to humans is unknown.

8.5 Geriatric Use

The safety, efficacy and pharmacokinetics of atomoxetine hydrochloride in geriatric patients have not been evaluated.

8.6 Hepatic Insufficiency

Atomoxetine exposure (AUC) is increased, compared with normal subjects, in EM subjects with moderate (Child-Pugh Class B) (2 fold increase) and severe (Child-Pugh Class C) (4 fold increase) hepatic insufficiency. Dosage adjustment is recommended for patients with moderate or severe hepatic insufficiency [ see Dosage and Administration ( 2.3) ].

8.7 Renal Insufficiency

EM subjects with end stage renal disease had higher systemic exposure to atomoxetine than healthy subjects (about a 65% increase), but there was no difference when exposure was corrected for mg/kg dose. Atomoxetine hydrochloride can therefore be administered to ADHD patients with end stage renal disease or lesser degrees of renal insufficiency using the normal dosing regimen.

8.8 Gender

Gender did not influence atomoxetine disposition.

8.9 Ethnic Origin

Ethnic origin did not influence atomoxetine disposition (except that PMs are more common in Caucasians).

8.10 Patients with Concomitant Illness

Tics in patients with ADHD and comorbid Tourette’s Disorder — Atomoxetine administered in a flexible dose range of 0.5 to 1.5 mg/kg/day (mean dose of 1.3 mg/kg/day) and placebo were compared in 148 randomized pediatric (age 7 to 17 years) subjects with a DSM-IV diagnosis of ADHD and comorbid tic disorder in an 18 week, double-blind, placebo-controlled study in which the majority (80%) enrolled in this trial with Tourette’s Disorder (Tourette’s Disorder: 116 subjects; chronic motor tic disorder: 29 subjects). A non-inferiority analysis revealed that atomoxetine hydrochloride did not worsen tics in these patients as determined by the Yale Global Tic Severity Scale Total Score (YGTSS). Out of 148 patients who entered the acute treatment phase, 103 (69.6%) patients discontinued the study. The primary reason for discontinuation in both the atomoxetine (38 of 76 patients, 50.0%) and placebo (45 of 72 patients, 62.5%) treatment groups was identified as lack of efficacy with most of the patients discontinuing at Week 12. This was the first visit where patients with a CGI-S ≥ 4 could also meet the criteria for “clinical non-responder” (CGI-S remained the same or increased from study baseline) and be eligible to enter an open-label extension study with atomoxetine. There have been postmarketing reports of tics [ see Adverse Reactions ( 6.2) ].

Anxiety in patients with ADHD and comorbid Anxiety Disorders — In two postmarketing, double-blind, placebo-controlled trials, it has been demonstrated that treating patients with ADHD and comorbid anxiety disorders with atomoxetine does not worsen their anxiety.

In a 12 week double-blind, placebo-controlled trial, 176 patients, aged 8 to 17, who met DSM-IV criteria for ADHD and at least one of the anxiety disorders of separation anxiety disorder, generalized anxiety disorder or social phobia were randomized. Following a 2 week double-blind placebo lead-in, atomoxetine was initiated at 0.8 mg/kg/day with increase to a target dose of 1.2 mg/kg/day (median dose 1.30 mg/kg/day +/- 0.29 mg/kg/day). Atomoxetine did not worsen anxiety in these patients as determined by the Pediatric Anxiety Rating Scale (PARS). Of the 158 patients who completed the double-blind placebo lead-in, 26 (16%) patients discontinued the study.

In a separate 16 week, double-blind, placebo-controlled trial, 442 patients aged 18 to 65, who met DSM-IV criteria for adult ADHD and social anxiety disorder (23% of whom also had Generalized Anxiety Disorder) were randomized. Following a 2 week double-blind placebo lead-in, atomoxetine was initiated at 40 mg/day to a maximum dose of 100 mg/day (mean daily dose 83 mg/day +/- 19.5 mg/day). Atomoxetine did not worsen anxiety in these patients as determined by the Liebowitz Social Anxiety Scale (LSAS). Of the 413 patients who completed the double-blind placebo lead-in, 149 (36.1%) patients discontinued the study. There have been postmarketing reports of anxiety [ see Adverse Reactions ( 6.2) ].

Overdosage

10.1 Human Experience

There is limited clinical trial experience with atomoxetine hydrochloride overdose. During postmarketing, there have been fatalities reported involving a mixed ingestion overdose of atomoxetine hydrochloride and at least one other drug. There have been no reports of death involving overdose of atomoxetine hydrochloride alone, including intentional overdoses at amounts up to 1400 mg. In some cases of overdose involving atomoxetine hydrochloride, seizures have been reported. The most commonly reported symptoms accompanying acute and chronic overdoses of atomoxetine hydrochloride 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 [ see Clinical Pharmacology ( 12.2) ].

10.2 Management of Overdose

Consult with a Certified Poison Control Center 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.

Clinical pharmacology

12.1 Mechanism of Action

The precise mechanism by which atomoxetine produces its therapeutic effects in Attention-Deficit/Hyperactivity Disorder (ADHD) is unknown, but is thought to be related to selective inhibition of the pre-synaptic norepinephrine transporter, as determined in ex vivo uptake and neurotransmitter depletion studies.

12.2 Pharmacodynamics

An exposure-response analysis encompassing doses of atomoxetine (0.5, 1.2 or 1.8 mg/kg/day) or placebo demonstrated atomoxetine exposure correlates with efficacy as measured by the Attention-Deficit/Hyperactivity Disorder Rating Scale-IV-Parent Version: Investigator administered and scored. The exposure-efficacy relationship was similar to that observed between dose and efficacy with median exposures at the two highest doses resulting in near maximal changes from baseline [ see Clinical Studies ( 14.2) ].

Cardiac Electrophysiology — The effect of atomoxetine hydrochloride on QTc prolongation was evaluated in a randomized, double-blinded, positive-(moxifloxacin 400 mg) and placebo-controlled, cross-over study in healthy male CYP2D6 poor metabolizers. A total of 120 healthy subjects were administered atomoxetine hydrochloride (20 mg and 60 mg) twice daily for 7 days. No large changes in QTc interval (i.e., increases > 60 msec from baseline, absolute QTc > 480 msec) were observed in the study. However, small changes in QTc interval cannot be excluded from the current study, because the study failed to demonstrate assay sensitivity. There was a slight increase in QTc interval with increased atomoxetine concentration.

12.3 Pharmacokinetics

Atomoxetine is well-absorbed after oral administration and is minimally affected by food. It is eliminated primarily by oxidative metabolism through the cytochrome P450 2D6 (CYP2D6) enzymatic pathway and subsequent glucuronidation. Atomoxetine has a half-life of about 5 hours. A fraction of the population (about 7% of Caucasians and 2% of African Americans) 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 about 24 hours) of atomoxetine compared with people with normal activity [extensive metabolizers (Ems)]. Drugs that inhibit CYP2D6, such as fluoxetine, paroxetine, and quinidine, cause similar increases in exposure.

The pharmacokinetics of atomoxetine have been evaluated in more than 400 children and adolescents in selected clinical trials, primarily using population pharmacokinetic studies. Single-dose and steady-state individual pharmacokinetic data were also obtained in children, adolescents, and adults. When doses were normalized to a mg/kg basis, similar half-life, C max, and AUC values were observed in children, adolescents, and adults. Clearance and volume of distribution after adjustment for body weight were also similar.

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