Pharmacotherapeutic group: Drugs for obstructive airways diseases, selective beta-2-adrenoreceptor agonists, ATC code: R03AC18
Mechanism of action
The pharmacological effects of beta2-adrenoceptor agonists are at least in part attributable to stimulation of intracellular adenyl cyclase, the enzyme that catalyses the conversion of adenosine triphosphate (ATP) to cyclic-3', 5'-adenosine monophosphate (cyclic monophosphate). Increased cyclic AMP levels cause relaxation of bronchial smooth muscle. In vitro studies have shown that indacaterol, a long-acting beta2-adrenergic agonist, has more than 24-fold greater agonist activity at beta2-receptors compared to beta1-receptors and 20-fold greater agonist activity compared to beta3-receptors.
When inhaled, indacaterol acts locally in the lung as a bronchodilator. Indacaterol is a partial agonist at the human beta2-adrenergic receptor with nanomolar potency. In isolated human bronchus, indacaterol has a rapid onset of action and a long duration of action.
Although beta2-receptors are the predominant adrenergic receptors in bronchial smooth muscle and beta1-receptors are the predominant receptors in the human heart, there are also beta2-adrenergic receptors in the human heart comprising 10-50% of the total adrenergic receptors. The precise function of beta2-adrenergic receptors in the heart is not known, but their presence raises the possibility that even highly selective beta2-adrenergic agonists may have cardiac effects.
Pharmacodynamic effects
Onbrez Breezhaler, administered once a day at doses of 150 and 300 microgram consistently provided clinically significant improvements in lung function (as measured by the forced expiratory volume in one second, FEV1) over 24 hours across a number of clinical pharmacodynamic and efficacy studies. There was a rapid onset of action within 5 minutes after inhalation, with an increase in FEV1 relative to baseline of 110-160 ml, comparable to the effect of the fast-acting beta2-agonist salbutamol 200 microgram and statistically significantly faster compared to salmeterol/fluticasone 50/500 microgram. Mean peak improvements in FEV1 relative to baseline were 250-330 ml at steady state.
The bronchodilator effect did not depend on the time of dosing, morning or evening.
Onbrez Breezhaler was shown to reduce lung hyperinflation, resulting in increased inspiratory capacity during exercise and at rest, compared to placebo.
Effects on cardiac electrophysiology
A double-blind, placebo- and active (moxifloxacin)-controlled study for 2 weeks in 404 healthy volunteers demonstrated maximum mean (90% confidence intervals) prolongations of the QTcF interval (in milliseconds) of 2.66 (0.55, 4.77) 2.98 (1.02, 4.93) and 3.34 (0.86, 5.82) following multiple doses of 150 microgram, 300 microgram and 600 microgram, respectively. There was no evidence of a concentration-delta QTc relationship in the range of doses evaluated.
As demonstrated in 605 patients with COPD in a 26-week, double-blind, placebo-controlled Phase III study, there was no clinically relevant difference in the development of arrhythmic events monitored over 24 hours, at baseline and up to 3 times during the 26-week treatment period, between patients receiving recommended doses of Onbrez Breezhaler treatment and those patients who received placebo or treatment with tiotropium.
Clinical efficacy and safety
The clinical development programme included one 12-week, two six-month (one of which was extended to one year to evaluate safety and tolerability) and one one-year randomised controlled studies in patients with a clinical diagnosis of COPD. These studies included measures of lung function and of health outcomes such as dyspnoea, exacerbations and health-related quality of life.
Lung function
Onbrez Breezhaler, administered once a day at doses of 150 microgram and 300 microgram, showed clinically meaningful improvements in lung function. At the 12-week primary endpoint (24-hour trough FEV1), the 150 microgram dose resulted in a 130-180 ml increase compared to placebo (p<0.001) and a 60 ml increase compared to salmeterol 50 microgram twice a day (p<0.001). The 300 microgram dose resulted in a 170-180 ml increase compared to placebo (p<0.001) and a 100 ml increase compared to formoterol 12 microgram twice a day (p<0.001). Both doses resulted in an increase of 40-50 ml over open-label tiotropium 18 microgram once a day (150 microgram, p=0.004; 300 microgram, p=0.01). The 24-hour bronchodilator effect of Onbrez Breezhaler was maintained from the first dose throughout a one-year treatment period with no evidence of loss in efficacy (tachyphylaxis).
Symptomatic benefits
Both doses demonstrated statistically significant improvements in symptom relief over placebo for dyspnoea and health status (as evaluated by Transitional Dyspnoea Index [TDI] and St. George's Respiratory Questionnaire [SGRQ], respectively). The magnitude of response was generally greater than seen with active comparators (Table 2). In addition, patients treated with Onbrez Breezhaler required significantly less rescue medication, had more days when no rescue medication was needed compared to placebo and had a significantly improved percentage of days with no daytime symptoms.
Pooled efficacy analysis over 6 months' treatment demonstrated that the rate of COPD exacerbations was statistically significantly lower than the placebo rate. Treatment comparison compared to placebo showed a ratio of rates of 0.68 (95% CI [ 0.47, 0.98]; p-value 0.036) and 0.74 (95% CI [0.56, 0.96]; p-value 0.026) for 150 microgram and 300 microgram, respectively.
Limited treatment experience is available in individuals of African descent.
Table 2 Symptom relief at 6 months treatment duration
| Treatment Dose (microgram) | Indacaterol 150 once a day | Indacaterol 300 once a day | Tiotropium 18 once a day | Salmeterol 50 twice a day | Formoterol 12 twice a day | Placebo |
| Percentage of patients who achieved MCID TDI† | 57 a 62 b | 71 b 59 c | 57 b | 54 a | 54 c | 45 a 47 b 41 c |
| Percentage of patients who achieved MCID SGRQ† | 53 a 58 b | 53 b 55 c | 47 b | 49 a | 51 c | 38 a 46 b 40 c |
| Reduction in puffs/day of rescue medication use vs. baseline | 1.3 a 1.5 b | 1.6 b | 1.0 b | 1.2 a | n/e | 0.3 a 0.4 b |
| Percentage of days with no rescue medication use | 60 a 57 b | 58 b | 46 b | 55 a | n/e | 42 a 42 b |
Study design with a: indacaterol 150 microgram, salmeterol and placebo; b: indacaterol 150 and 300 microgram, tiotropium and placebo; c: indacaterol 300 microgram, formoterol and placebo
† MCID = minimal clinically important difference (≥1 point change in TDI, ≥4 point change in SGRQ)
n/e= not evaluated at six months
Paediatric population
The European Medicines Agency has waived the obligation to submit the results of studies with Onbrez Breezhaler in all subsets of the paediatric population in chronic obstructive pulmonary disease (COPD) (see section 4.2 for information on paediatric use).