Systemic Safety and Pharmacokinetic/Pharmacodynamic Relationships

The predominant adverse effects of inhaled beta2-agonists occur as a result of excessive activation of systemic beta-adrenergic receptors. The most common adverse effects may include skeletal muscle tremor and cramps, insomnia, tachycardia, decreases in plasma potassium, and increases in plasma glucose.

Effects on Serum Potassium and Serum Glucose Levels

Changes in serum potassium and serum glucose were evaluated in a dose-ranging study of twice daily (5 mcg, 15 mcg, or 25 mcg; 215 patients with COPD) and once daily (15 mcg, 25 mcg, or 50 mcg; 191 patients with COPD) arformoterol tartrate inhalation solution in COPD patients. At 2 and 6 hours post dose at week 0 (after the first dose), mean changes in serum potassium ranging from 0 to -0.3 mEq/L were observed in the arformoterol tartrate inhalation solution groups with similar changes observed after 2 weeks of treatment. Changes in mean serum glucose levels, ranging from a decrease of 1.2 mg/dL to an increase of 32.8 mg/dL were observed for arformoterol tartrate inhalation solution dose groups at both 2 and 6 hours post dose, both after the first dose and 14 days of daily treatment.

Electrophysiology

The effect of arformoterol tartrate inhalation solution on QT interval was evaluated in a dose-ranging study following multiple doses of arformoterol tartrate inhalation solution 5 mcg, 15 mcg, or 25 mcg twice daily or 15 mcg, 25 mcg, or 50 mcg once daily for 2 weeks in patients with COPD. ECG assessments were performed at baseline, time of peak plasma concentration and throughout the dosing interval. Different methods of correcting for heart rate were employed, including a subject-specific method and the Fridericia method.

Relative to placebo, the mean change in subject-specific QTc averaged over the dosing interval ranged from -1.8 to 2.7 msec, indicating little effect of arformoterol tartrate inhalation solution on cardiac repolarization after 2 weeks of treatment. The maximum mean change in subject-specific QTc for the arformoterol tartrate inhalation solution 15 mcg twice daily dose was 17.3 msec, compared with 15.4 msec in the placebo group. No apparent correlation of QTc with arformoterol plasma concentration was observed.

Electrocardiographic Monitoring in Patients with COPD

The effect of different doses of arformoterol tartrate inhalation solution on cardiac rhythm was assessed using 24-hour Holter monitoring in two 12-week, double-blind, placebo-controlled studies of 1,456 patients with COPD (873 received arformoterol tartrate inhalation solution at 15 or 25 mcg twice daily or 50 mcg once daily doses; 293 received placebo; 290 received salmeterol). The 24-hour Holter monitoring occurred once at baseline, and up to 3 times during the 12-week treatment period. The rates of new-onset cardiac arrhythmias not present at baseline over the double-blind 12-week treatment period were similar (approximately 33-34%) for patients who received arformoterol tartrate inhalation solution 15 mcg twice daily to those who received placebo. There was a dose-related increase in new, treatment-emergent arrhythmias seen in patients who received arformoterol tartrate inhalation solution 25 mcg twice daily and 50 mcg once daily, 37.6% and 40.1%, respectively. The frequencies of new treatment-emergent events of non-sustained (3 to 10 beat run) and sustained (>10 beat run) ventricular tachycardia were 7.4% and 1.1% in arformoterol tartrate inhalation solution 15 mcg twice daily and 6.9% and 1.0% in placebo. In patients who received arformoterol tartrate inhalation solution 25 mcg twice daily and 50 mcg once daily, the frequencies of non-sustained (6.2% and 8.2%, respectively) and sustained ventricular tachycardia (1.0% and 1.0%, respectively) were similar. Five cases of ventricular tachycardia were reported as adverse events (1 in arformoterol tartrate inhalation solution 15 mcg twice daily and 4 in placebo), with two of these events leading to discontinuation of treatment (2 in placebo).

There were no baseline occurrences of atrial fibrillation/flutter observed on 24-hour Holter monitoring in patients treated with arformoterol tartrate inhalation solution 15 mcg twice daily or placebo. New, treatment-emergent atrial fibrillation/flutter occurred in 0.4% of patients who received arformoterol tartrate inhalation solution 15 mcg twice daily and 0.3% of patients who received placebo. There was a dose-related increase in the frequency of atrial fibrillation/flutter reported in the arformoterol tartrate inhalation solution 25 mcg twice daily and 50 mcg once daily dose groups of 0.7% and 1.4%, respectively. Two cases of atrial fibrillation/flutter were reported as adverse events (1 in arformoterol tartrate inhalation solution 15 mcg twice daily and 1 in placebo).

Dose-related increases in mean maximum change in heart rate in the 12 hours after dosing were also observed following 12 weeks of dosing with arformoterol tartrate inhalation solution 15 mcg twice daily (8.8 bpm), 25 mcg twice daily (9.9 bpm) and 50 mcg once daily (12 bpm) versus placebo (8.5 bpm).

Tachyphylaxis/Tolerance

Tolerance to the effects of inhaled beta-agonists can occur with regularly-scheduled, chronic use. In two placebo-controlled clinical trials in patients with COPD involving approximately 725 patients in each, the overall efficacy of arformoterol tartrate inhalation solution was maintained throughout the 12-week trial duration. However, tolerance to the bronchodilator effect of arformoterol tartrate inhalation solution was observed after 6 weeks of dosing, as measured by a decrease in trough FEV1. FEV1 improvement at the end of the 12-hour dosing interval decreased by approximately one-third (22.1% mean improvement after the first dose compared to 14.6% at week 12). Tolerance to the trough FEV1 bronchodilator effect of arformoterol tartrate inhalation solution was not accompanied by other clinical manifestations of tolerance in these trials.