Editorial [Hot Topic: Molecular Targets in Chronic Obstructive Airway Diseases (Guest Editors: David A. Groneberg and Tobias Welte)]

Chronic obstructive respiratory diseases, such as bronchial asthma and chronic obstructive pulmonary disease (COPD) are related to potential numerous causes (Fig. 1) and belong to the major growth areas of pharmacology and pharmaceutics and there is a large variety of new compounds currently in development. These new agents include both substances that represent improvements of existing classes of drugs such as corticosteroids or beta 2 receptor agonists and completely new classes of drugs. These new classes have been developed in the past years due to an improved understanding of the complex pathophysiology of obstructive airway diseases and include agonists and antagonists of specific extracellular and intracellular mediators such as cytokines or chemokines. Bronchial asthma displays an important health care problem, as it exerts a tremendous toll on patients, health care providers, and the societies. The substantial increase in the prevalence of obstructive airway diseases in recent decades has generated sizable concern from both domestic and global perspectives. Epidemiologically, the incidence of allergic diseases, including bronchial asthma has increased in developed countries over the past several decades and these diseases comprise a large component of the work of general practices. Also, in the pediatric sector, asthma-like syndromes represent the most frequent cause of hospitalization in children in western countries. The socio-economic effect of these diseases are high and still increasing. In 1996, 17 million US-Americans, with approximately one third of those being children, were affected by bronchial asthma and the economic burden of the disease is increasing in parallel, from an estimated US$6.2 billion in 1990 to US$12.7 billion in 1998 [1]. These costs include direct medical costs (58%) as well as indirect costs (42%) such as school days lost, loss of work, housekeeping and mortality [1]. Initially identified as a new major medical and socio-economic burden in developed countries, the increase in asthma prevalence is now also becoming more evident in rapidly developing countries in the Third World and in emerging Second World countries transiting to First World economic status and. As an example, the prevalence of asthma has increased in Bangalore, India, a city known for its high asthma prevalence, from 9.0% of the pediatric population in 1979 to 29.5% in 1999 [1]. Similar trends are reported from other parts of the Asian region, such as China. Based on prevalence rates at present and projected increases, it can be estimated that the total population of asthmatic patients in China will be around 150 million, including 38 million children, by the year 2013. These epidemiologic findings point to considerable challenges for public health not only in the developed countries, but globally [2]. With regard to the spiraling treatment costs it is currently debated that there should be a substantial realignment of drug development policy in the pharmaceutical industry and parallel shift in the licensing policy by authorities to encourage the development of novel compounds that are effective in halting the progression from acute to chronic forms of obstructive diseases when the diseases first manifest in early childhood [3]. Since corticosteroids are clinically effective, relatively safe, and easy to administer, they remain the gold standard of anti-inflammatory treatment in bronchial asthma. However, inhaled corticosteroids have failed to halt the progression of the asthma epidemic and they are ineffective in the small group of patients with glucocorticoiddependent and -resistant asthma. Chronic obstructive pulmonary disease on the other hand is mainly caused by tobacco smoking. Therefore, with very few exceptions, smoking cessation displays the only causative and effective treatment of COPD. In this respect, the current pharmacological treatment options of COPD have been found to be more or less unsatisfactory, since they do not influence the natural course or disease severity significantly. In COPD patients without concomitant asthma glucocorticoids are scarcely effective. While bronchodilators may improve symptoms and quality of life in COPD patients, they do not significantly influence the natural course of COPD with the exception of tiotropium and only theophylline has been demonstrated to have significant effects on airway inflammation in patients with COPD. It is also important to mention that the pharmacologic treatment options are not curative but current and future approaches may lead to a better long-term control of chronic airway obstruction. In this respect, it is a major aim to develop novel agents that are as effective existing drugs but have less side effects and have a better route of administration [4, 5]. The present theme issue of Current Drug Targets aims to provide a series of reviews that focus on current aspects of respiratory drug development...........