Main Objective: To assess whether the time of dosing (a.m. or p.m.) at steady state influences the bronchodilator response of aclidinium bromide compared to placebo in patients with moderate to severe COPD.;Secondary Objective: To further evaluate the safety and tolerability of multiple doses of aclidinium bromide in moderate to severe COPD patients.;Primary end point(s): Efficacy variables:<br><br>Primary efficacy variable:<br>• Change from baseline in the trough FEV1 after 6 days of treatment.<br><br>Secondary efficacy variables:<br>• Change from baseline in the trough FVC after 6 days of treatment.<br>• Change from baseline in the trough IC after 6 days of treatment.<br>• Change from baseline in the FEV1 and FVC at all time-points after 7 days of treatment in the a.m. regimen and after 6-7 days of treatment in the p.m. regimen.<br>• Change from baseline in the IC at all time-points after 7 days of treatment in the a.m. regimen and after 6-7 days of treatment in the p.m. regimen.<br>• Change from baseline in the peak FEV1 and FVC after 7 days of treatment.<br>• Change from baseline in normalised FEV1 and FVC AUC0-24 after 7 days of treatment in the a.m. regimen and after 6-7 days of treatment in the p.m. regimen.<br>• Change from baseline in normalised FEV1 and FVC AUC0-12 after 7 days of treatment.<br>• Change from baseline in normalised FEV1 and FVC AUC12-24 after 7 days of treatment in the a.m. regimen and after 6 days of treatment in the p.m. regimen.<br>• Use of as needed” daily rescue medication (number of salbutamol puffs, as recorded by the patient during the treatment period).<br><br>Safety variables:<br>• Adverse Events (AEs).<br>• Serious Adverse Events (SAEs).<br>• 12-lead ECG parameters.<br>• Blood pressure parameters.<br>• Laboratory parameters (standard haematology, biochemistry and urinalysis).<br>• Physical examination.<br><br>Other variables:<br>• Use of concomitant medication.<br>• Number (%) of withdrawals and reasons for withdrawal.;Main Objective: To assess whether the time of dosing (a.m. or p.m.) at steady state influences the bronchodilator response of aclidinium bromide compared to placebo in patients with moderate to severe COPD.;Secondary Objective: To further evaluate the safety and tolerability of multiple doses of aclidinium bromide in moderate to severe COPD patients.;Primary end point(s): Efficacy variables:<br><br>Primary efficacy variable:<br>• Change from baseline in the trough FEV1 after 6 days of treatment.<br><br>Secondary efficacy variables:<br>• Change from baseline in the trough FVC after 6 days of treatment.<br>• Change from baseline in the trough IC after 6 days of treatment.<br>• Change from baseline in the FEV1 and FVC at all time-points after 7 days of treatment in the a.m. regimen and after 6-7 days of treatment in the p.m. regimen.<br>• Change from baseline in the IC at all time-points after 7 days of treatment in the a.m. regimen and after 6-7 days of treatment in the p.m. regimen.<br>• Change from baseline in the peak FEV1 and FVC after 7 days of treatment.<br>• Change from baseline in normalised FEV1 and FVC AUC0-24 after 7 days of treatment in the a.m. regimen and after 6-7 days of treatment in the p.m. regimen.<br>• Change from baseline in normalised FEV1 and FVC AUC0-12 after 7 days of treatment.<br>• Change from baseline in normalised FEV1 and FVC AUC12-24 after 7 days of treatment in the a.m. regimen and after 6 days of treatment in the p.m. regimen.<br>• Use of as needed” daily rescue medication (number of salbutamol puffs, as recorded by the patient during the treatment period).<br><br>Safety variables:<br>• Adverse Events (AEs).<br>• Serious Adverse Events (SAEs).<br>• 12-lead ECG parameters.<br>• Blood pressure parameters.<br>• Laboratory parameters (standard haematology, biochemistry and urinalysis).<br>• Physical examination.<br><br>Other variables:<br>• Use of concomitant medication.<br>• Number (%) of withdrawals and reasons for withdrawal.