Increased systemic exposure w/ CYP3A4 inhibitors eg, ketoconazole. β-blockers may partially or totally inhibit effect of β
2-agonists. Cumulative effect w/ other β-adrenergic stimulants or sympathomimetic amines (eg, ephedrine). Potentiated hypokalaemia w/ xanthine derivatives, mineralocorticosteroids, & diuretics. Exacerbated CV effects w/ MAOIs, TCAs, quinidine, disopyramide, procainamide, phenothiazines, or antihistamines (eg, terfenadine, astemizole).