The present invention relates to metered dose inhalers for the administration of active medicaments/propellants and excipients. The invention provides a pMDI inhaler comprising a pMDI canister 22, a vortex device, an integral horn and a breath-activated mechanism 26, 28, 34 wherein the canister contains a formulation comprising a combination of two or more active ingredients. Proposed active ingredients include beta agonists, inhaled corticosteroids and anticholinergics. The integral horn may have a shape which widens towards the mouthpiece, thus reducing the aerosol flow velocity.
