ABSTRACT
Drugs and medicinal agents administered by the inhalation route include gaseous and vaporous anesthetics, coronary vasodilators, and aerosols of bronchodilators, corticosteroids, mucolytics, expectorants, antibiotics, and an increasing number of peptides and proteins where there is signicant nasal absorption (Cox et al. 1970; Williams 1974; Paterson et al. 1979; Hodson et al. 1981; Lourenco and Cotromanes 1982, Tamulinas and Leach, 2000). Concerns with the environmental effects of chlorouorocarbons have also led to renewed interest in dry powder inhalers (DPIs), which have additionally shown promise for better tolerance and absorption for some new drugs. Recent advances have also led to new nasal delivery systems, such as in Table 22.1. Excessive inhalation of a drug into the pulmonary system during therapy or manufacturing may result in adverse local and/ or systemic effects. Consequently, safety assessment of medicinal preparations delivered via respiratory routes with respect to local tissue toxicity, systemic toxicity, and the therapeutic-to-toxicity ratio is essential. The data generated are essential for charting the course of evaluation and the development of a potential therapeutic agent, the general course of which is summarized in Figure 22.1.
