Asthma treatment aims

Aerosolised medicines have been used for centuries to treat respiratory diseases, with inhalation therapy for the airways focused primarily on the treatment of asthma and chronic obstructive pulmonary disease (COPD). The development of new products for delivery to the lungs for these respiratory diseases includes new steroids and beta agonists plus combination products featuring both agents. New classes of anti-asthma medication are also being developed for inhalation with the aim of delivering them directly to the inflamed airways. 

It must be our aim to prevent the development of asthma in patients, especially in children with rhinitis, and SIT has been shown to considerably reduce the risk of disease expansion in this group of patients that otherwise would develop asthma in about 35-45% of cases. SIT clearly is a treatment of choice for common airway disease such as a reductive and preventive treatment approach. Further studies are needed to confirm this benefit and to allow a better classification of patients suitable for preventive SIT in terms of sensitizations, age and laboratory parameters. 

Many drugs have been formnlated for use with pressurized metered-dose inhalers (pMDIs) (Table 1). The main market for these devices is in the treatment of asthma, allergic diseases, and chronic obstructive pulmonary disease (COPD), for which approximately 500 million pMDIs are produced each year. Their major selling points are that they are cheap and portable. Despite their huge sales, there is increasing concern that the dose of drug patients with asthma receive will vary considerably due to their inhalational technique and to a lesser extent to the variabihty of dose delivery from the pMDI. It is likely, however, that the popularity of pMDIs will continue due to various modifications and additions that are aimed to help with inhalational technique and improve drug delivery. Examples of these include breath-actuated devices, discussed in this chapter, and spacer devices discussed in a subsequent chapter. 

The Austrian pharmacologist Heribert Konzett (1912-2004) had discovered in 1940 isoprenaUne, which should become the prototype of p-selective sympathomimetics. Due to its bronchodilatory properties, but without causing hyper-tention, it was considered the drug of choice to treat asthmatic attacks. With almost equally strong effect on pj- and p2-receptors, it was of concern, that isoprenaline acts as a very potent cardiac stimulant. Further structural optimisation then led to more selective pj-sympathomimetics, like dobutamine, for the treatment of heart failure and cardiogenic shock, while selective p2-sympathomimetics were aimed at safer therapies of bronchial asthma. 

Pulmonary administration of medicines currently has the primary objective to achieve local effects in the respiratory tract of patients with chronic diseases like asthma, chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF). For half a century, inhalation therapy has been the cornerstone in the management of these diseases and the often life-time therapies aim to suppress inflammatory processes and bacterial infection in order to reduce hospitalisations and to improve the patient s quality of life. They also give relief to the patient in moments of bronchoconstriction. The advantages of pulmonary administration of medicines for local treatment are well known. The active substances are delivered directly to the site of action which leads to a faster response than via the systemic route. It may also result in higher local active substance concentrations and this could reduce the total dose by as much as a factor 10 compared to oral or intravenous administration. This has the advantage that systemic side effects are reduced and in combination with being a non-invasive method of administration, inhalation therapy may lead to better patient compliance. 

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