ABSTRACT
Limitations of Experimental Provocation Models 187
evolved (see Table 1). Occasionally, such methods are laboratory-specific. These include delivery on one versus two consecutive days and nasal drop instillation with or without the addition of nasal spray from an atomizer and/or nasal inhalation from a nebulizer. Some of these methods have been designed to enhance lower airway deposition (5,8-14). Unfortunately, none of these methods has been tested for comparability or validity in controlled settings. Interestingly, it has been reported that rhinovirus 16 had no effect on lower airway reactivity to methacholine when administered by nasal drops alone, but it did have a positive effect when spray from an atomizer was added to this method (7 ,8).
