Inhalation Therapy of the Future - How Will It Change the Way We Treat Asthma?

Inhalation of drugs has made a great difference in terms of optimizing asthma therapy. The challenge for the next generation of inhalers will be to provide still greater benefits to patients in terms of efficacy, safety, and convenience. Dry powder inhalers (DPIs) are innovative new inhalation devices and comparisons with pressurized metered dose inhalers (pMDIs) show that DPIs are at least as efficient at delivering drugs, and may be a superior delivery device for some drugs. To compare different inhaler devices, drug dose comparisons that lie on the slope of the dose-response curve should be selected, and it is important to analyze the risk:benefit ratio (therapeutic ratio). Some of the new devices contain aerosols with a smaller particle size than current designs. Monodispersed aerosols with a very narrow range of particle sizes may target drug delivery to specific areas of the lung where it is most effective. However, as smaller particles are more easily absorbed into the pulmonary circulation via the alveoli, these formulations may be associated with a higher incidence of systemic side effects. The optimal particle size required to maximize the therapeutic ratio of a molecule may be different for a β₂-agonist than for an inhaled corticosteroid. A greater understanding of this relationship will be required if we are to achieve better drug targeting with future inhalers.