Repiratory Tract

This chapter discusses respiratory tract. This chapter illustrates that a complex array of defensive mechanisms protect the lungs against the adverse effects of airborne substances and pathogenic organisms. In contrast to the adverse pulmonary effects of cigarette smoke and industrial pollutants, therapeutic agents remain a relatively minor cause of pulmonary toxicity in man although, actual incidence is difficult to ascertain. However, drug-induced pulmonary disease appears to be an increasingly frequent clinical problem and the drugs associated with parenchymal pulmonary injury in humans continue to increase. The development of drugs to be administered by inhalation or intranasal routes is particularly difficult because of the perceived risks of high local drug concentration in respiratory tissues, alterations to drug disposition and a potentially vulnerable patient population, often with pulmonary disease. Finally, the nasal chambers are the structures, which are first to be subjected to the effects of inhaled substances, whether microorganisms or chemical substances. Moreover, infectious agents cause inflammation in the nose and nasal sinuses, and this may be associated with inflammation in the conjunctiva, middle ear and oral cavity.