Atomoxetine Hydrochloride (Page 4 of 11)

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 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 [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 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 (2.5) and Drug Interactions (7.2)].

6 ADVERSE REACTIONS

6.1 Clinical Trials Experience

Atomoxetine 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-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 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 (incidence of 2% or greater) and not observed at an equivalent incidence among placebo-treated patients (atomoxetine 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 (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 in Acute (up to 18 weeks) Child and Adolescent Trials

Adverse Reactiona Percentage of Patients Reporting Reaction
  Atomoxetine (N=1597) Placebo (N=934)
Gastrointestinal Disorders    
  Abdominal painb 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
  Somnolencec 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 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 (N=715) Placebo (N=434) Atomoxetine (N=882) Placebo (N=500)
Gastrointestinal Disorders        
  Abdominal paina 17 13 18 7
  Vomiting 11 8 11 4
  Nausea 7 6 13 4
  Constipationb 2 1 1 0
General Disorders        
  Fatigue 6 4 9 2
Psychiatric Disorders        
  Mood swingsc 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.

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