In this issue of the Journal we start a new review series on research methods in human respiratory pharmacology. Drug delivery to the respiratory system provides unique problems for the clinical pharmacologist. In particular, the apparently simple process of inhaling drug is fraught with numerous physical, mechanical and biological problems. It is entirely appropriate therefore that we start the review series by asking Henry Chrystyn to give an overview of the different methods used to characterize drug deposition within the lungs. In this field, controversy rages between those who advocate the extensive use of gamma scintigraphy and those who advocate either pharmacokinetic or pharmacodynamic measurements. In reality these techniques provide different datasets of information. In my view the direct visualization of drug deposition within the airways provides extremely valuable information, particularly as it may be possible to use these techniques to give information about individual patients. Pharmacokinetic methods give information that defines the proportion of drug delivered to different compartments. This accurate differentiation between inhaled and swallowed components is invaluable in the assessment of safety and can be readily applied in both health and disease. Both gamma scintigraphy and pharmacokinetic studies provide valuable supportive data in our understanding of the clinical pharmacology of inhaled drugs. In an area where some of our most effective agents such as the inhaled steroids are extremely difficult to study using therapeutic end points, a thorough knowledge of the strengths and pitfalls of these alternative methods is vital for the proper assessment of data.
For future reviews in this series, I have commissioned papers in a diverse series of methods, which we use to assess the pharmacological response of the respiratory tract. Noninvasive measures of drug effect are particularly valuable when we are dealing with an organ so difficult to get at as the lung. Sputum induction and assessment of the cellular and biochemical profile of sputum will be reviewed in the next paper in this series. Other topics include bronchial challenge in asthma, cough challenge by inhaled tussive agents in the development of antitussive therapy, and conventional physiological techniques for the assessment of bronchodilator efficacy. If any of our readers feel that they could make a contribution to our understanding of other topics related to the clinical pharmacology of the respiratory tract I would be delighted to hear from them.