Enhanced bronchodilatory effect w/ other β-adrenergics, anticholinergics, xanthine derivatives eg, theophylline. Potentially serious reduced bronchodilation w/ β-blockers. Increased β
2-agonist-induced hypokalaemia w/ xanthine derivatives, corticosteroids, diuretics. Increased susceptibility to arrhythmias w/ digoxin. Enhanced action w/ MAOIs or TCAs. Increased susceptibility on CV effects w/ halogenated hydrocarbon anaesth inhalation eg, halothane, trichloroethylene & enflurane. Not recommended in co-administration w/ other anticholinergic drugs.