Aclidinium is a long-acting muscarinic antagonist (also known as an anticholinergic) and formoterol is a long-acting β2-adrenergic agonist. The combination of these substances with different mechanisms of action results in additive efficacy compared to that achieved with either component alone. As a consequence of the differential density of muscarinic receptors and β2-adrenoceptors in the central and peripheral airways of the lung, muscarinic antagonists should be more effective in relaxing central airways and β2-adrenergic agonists should be more effective in relaxing peripheral airways; relaxation of both central and peripheral airways with combination treatment may contribute to its beneficial effects on lung function. Further information regarding these two substances is provided below.
Aclidinium is a competitive, selective muscarinic receptor antagonist, with a longer residence time at the M3 receptors than the M2 receptors. M3 receptors mediate contraction of airway smooth muscle. Inhaled aclidinium bromide acts locally in the lungs to antagonise M3 receptors of airway smooth muscle and induce bronchodilation. Aclidinium has also been shown to provide benefits to patients with COPD in terms of symptoms reduction, improvement in disease-specific health status, reduction in exacerbation rates and improvements in exercise tolerance. Since aclidinium bromide is quickly broken down in plasma, the level of systemic anticholinergic undesirable effects is low.
Formoterol is a potent selective β2-adrenoceptor agonist. Bronchodilation is induced by causing direct relaxation of airway smooth muscle as a consequence of the increase in cyclic AMP through activation of adenylate cyclase. In addition to improving pulmonary function, formoterol has been shown to improve symptoms and quality of life in patients with COPD.
Clinical efficacy studies showed that aclidinium/formoterol provides clinically meaningful improvements in lung function (as measured by the forced expiratory volume in 1 second [FEV1]) over 12 hours following administration.
Aclidinium/formoterol demonstrated a rapid onset of action within 5 minutes of the first inhalation relative to placebo (p<0.0001). The onset of action of aclidinium/formoterol was comparable to the effect of the fastacting β2-agonist formoterol 12 micrograms. Maximal bronchodilator effects (peak FEV1) relative to baseline were evident from day one (304 ml) and were maintained over the 6-month treatment period (326 ml).
No clinically relevant effects of aclidinium/formoterol on ECG parameters (including QT-interval) compared with aclidinium, formoterol and placebo were seen in Phase III studies of 6 to 12 months duration conducted in approximately 4,000 patients with COPD. No clinically significant effects of aclidinium/formoterol on cardiac rhythm were observed on 24-hour Holter monitoring in a subset of 551 patients, of whom 114 received aclidinium/formoterol twice daily. Clinical Efficacy and Safety The Phase III clinical development programme included approximately 4,000 patients with a clinical diagnosis of COPD and comprised two 6-month randomised, placebo- and active-controlled studies (ACLIFORM-COPD and AUGMENT), a 6-month extension of the AUGMENT study and a further 12-month randomised controlled study. During these studies, patients were permitted to continue their stable treatment with inhaled corticosteroids, low doses of oral corticosteroids, oxygen therapy (if less than 15h/day) or methylxanthines and to use salbutamol as rescue medication.
Efficacy was assessed by measures of lung function, symptomatic outcomes, disease-specific health status, rescue medication use, and exacerbations. In long-term safety studies, aclidinium/formoterol was associated with sustained efficacy when administered over a one-year treatment period with no evidence of tachyphylaxis.
When aclidinium and formoterol were administered in combination by the inhaled route, the pharmacokinetics of each component showed no relevant differences from those observed when the medicinal products were administered separately.
Following inhalation of a single dose of 340 micrograms aclidinium/12 micrograms formoterol , aclidinium and formoterol were rapidly absorbed into plasma, reaching peak plasma concentrations within 5 minutes of inhalation in healthy subjects and within 24 minutes of inhalation in patients with COPD. The peak plasma concentrations at steady state of aclidinium and formoterol observed in patients with COPD treated with aclidinium/formoterol twice daily for 5 days were reached within 5 minutes post-inhalation and were 128 pg/ml and 17 pg/ml, respectively.
Whole lung deposition of inhaled aclidinium via Genuair averaged approximately 30% of the metered dose. The plasma protein binding of aclidinium determined in vitro most likely corresponded to the protein binding of the metabolites due to the rapid hydrolysis of aclidinium in plasma; plasma protein binding was 87% for the carboxylic acid metabolite and 15% for the alcohol metabolite. The main plasma protein that binds aclidinium is albumin.
The plasma protein binding of formoterol is 61% to 64% (34% primarily to albumin). There is no saturation of binding sites in the concentration range reached with therapeutic doses.
Aclidinium is rapidly and extensively hydrolysed to its pharmacologically inactive alcohol- and carboxylic acid-derivatives. Plasma levels of the acid metabolite are approximately 100-fold greater than those of the alcohol metabolite and the unchanged active substance following inhalation. The hydrolysis occurs both chemically (non-enzymatically) and enzymatically by esterases, butyrylcholinesterase being the main human esterase involved in the hydrolysis. The low absolute bioavailability of inhaled aclidinium (<5%) is because aclidinium undergoes extensive systemic and pre-systemic hydrolysis whether deposited in the lung or swallowed. Biotransformation via CYP450 enzymes plays a minor role in the total metabolic clearance of aclidinium. In vitro studies have shown that aclidinium at the therapeutic dose or its metabolites do not inhibit or induce any of the cytochrome P450 (CYP450) enzymes and do not inhibit esterases (carboxylesterase, acetylcholinesterase and butyrylcholinesterase). In vitro studies have shown that aclidinium or its metabolites are not substrates or inhibitors of P-glycoprotein.
Formoterol is eliminated primarily by metabolism. The prominent pathway involves direct glucuronidation, with O-demethylation followed by glucuronide conjugation being a further metabolic pathway. Cytochrome P450 isoenzymes CYP2D6, CYP2C19, CYP2C9 and CYP2A6 are involved in the O-demethylation of formoterol. Formoterol does not inhibit CYP450 enzymes at therapeutically relevant concentrations.
Following inhalation of 340 micrograms aclidinium/12 micrograms formoterol , with plasma sampling up to 24 hours post-dose, the terminal elimination half-life observed for aclidinium bromide ranged from 11-33 hours and for formoterol from 12-18 hours.
Mean effective half-lives* observed for both aclidinium and formoterol (based on the accumulation ratio) are approximately 10 hours.
* Half-life consistent with product accumulation based on a known dose regimen.
Following intravenous administration of radiolabelled aclidinium 400 micrograms to healthy subjects, approximately 1% of the dose was excreted as unchanged aclidinium bromide in the urine. Up to 65% of the dose was eliminated as metabolites in the urine and up to 33% as metabolites in the faeces. Following inhalation of aclidinium 200 micrograms and 400 micrograms by healthy subjects or patients with COPD, the urinary excretion of unchanged aclidinium was very low at about 0.1% of the administered dose, indicating that renal clearance plays a minor role in the total aclidinium clearance from plasma.
The major part of a dose of formoterol is transformed by liver metabolism followed by renal elimination. After inhalation, 6% to 9% of the delivered dose of formoterol is excreted in the urine unchanged or as direct conjugates of formoterol.
No pharmacokinetics studies have been performed with aclidinium/formoterol in elderly subjects. Since no dosage adjustments are needed for either aclidinium or formoterol medicinal products in elderly patients, no dosage adjustment is warranted for aclidinium/formoterol in geriatric patients.
There are no data regarding the specific use of aclidinium/formoterol in patients with renal or hepatic impairment. Since no dosage adjustments are needed for either aclidinium or formoterol medicinal products in patients with renal or hepatic impairment, no dosage adjustment is warranted for aclidinium/formoterol.
Following repeated inhalations of 340 micrograms aclidinium/12 micrograms formoterol , the systemic exposure of aclidinium and formoterol, as measured by AUC, is similar in Japanese and Caucasian patients.
Nonclinical data reveal no special hazard for humans with aclidinium and formoterol based on conventional studies of safety pharmacology, repeated dose toxicity, genotoxicity, and carcinogenic potential and toxicity to reproduction and development.
Effects of aclidinium in nonclinical studies with respect to reproductive toxicity (foetotoxic effects) and fertility (slight decreases in conception rate, number of corpora lutea, and pre- and postimplantation losses) were observed only at exposures considered sufficiently in excess of the maximum human exposure indication to be of little relevance to clinical use.
Formoterol showed reduced fertility (implantation losses) in rats, as well as decreased early postnatal survival and birth weight with high systemic exposure to formoterol. A slight increase in the incidence of uterine leiomyomas has been observed in rats and mice; an effect which is considered to be a classeffect in rodents after long-term exposure to high doses of β2-adrenoreceptor agonists.
Nonclinical studies investigating the effects of aclidinium/formoterol on cardiovascular parameters showed increased heart rates and arrhythmias at exposures sufficiently in excess of the maximum human exposure indication to be of little relevance to clinical use. These effects are known exaggerated pharmacological responses observed with β2-agonists.
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