Richard Turner, business development director at Presspart, looks at inhaler development and recent improvements

An estimated 300 million people suffer from asthma and a further 210 million from chronic obstructive pulmonary disease. The primary treatment is through inhaled aerosol medications containing agents such as b-agonists, anti-cholinergic agents and corticosteroids. The technology has evolved in recent decades to address regulatory, cost and compliance issues, but challenges remain to ensure each dose delivered by the device provides the correct level of drug to the appropriate part of the respiratory system.

Respiratory Delivery

Inhaled aerosols are favoured due to their selective treatment of the lungs, achieving high drug concentrations in the airway while minimising systemic drug levels. Aerosol drug delivery is painless, and for some drugs (e.g. b-2-agonists) the onset of action is faster than oral drugs; 2 some corticosteroids are active therapeutically only when they are inhaled.

Nebulisers, pressurised metered dose inhalers (MDIs) and dry powder inhalers (DPIs) each have advantages and disadvantages, depending on factors such as the patient’s age, severity of condition, situation (e.g. hospitalised versus out-patient), and ability to operate the device.

Nebulisers were the only available device for delivering inhaled aerosol drugs until the pressurised MDI was developed in 1955. Several types are in use today, particularly pneumatic jet nebulisers, which are powered by a gas source that aerosolises the drug solution and delivers it to the patient via a mouthpiece or face mask. These are widely used to treat patients unable to operate a portable inhaler due to lack of co-ordination, in cases such as infancy, disability, hospitalisation or severe illness.

Nebulisers” advantages include the flexibility to adjust the dose over time as required, and the ability to provide high doses to seriously ill patients. They can also deliver combination therapies (if compatible).

However, they have many disadvantages, in particular a lack of portability that results from their cumbersome design and the fact that they commonly need a source of pressurised gas to function. Treatment can require relatively long periods of administration (minutes or hours), and it is usually necessary to prepare the device prior to treatment and clean it afterwards.