Pharmacokinetic and pharmacodynamic evaluation of the suitability of using fluticasone and an acute rat lung inflammation model to differentiate lung versus systemic efficacy.

Inhaled corticosteroids (ICSs) are often prescribed as the first line therapy for pulmonary diseases such as asthma. The biggest concern of using steroid therapy is the systemic side effects at high dose. To reduce the side effects, the pharmaceutical industry has been putting effort to generate new drugs with maximized topical efficacy. One of the key challenges is to differentiate efficacy from local versus systemic contribution in preclinical animal models. Fluticasone with various formulations was used as a model compound to explore the possibilities to demonstrate lung targeted efficacy by intratracheally instillation in the lipopolysaccharide induced inflammation rat model. Fluticasone formulations contained various surfactant concentrations and particle sizes to achieve lung retention and lower systemic exposure. Neutrophil infiltration in broncoalveolar lavage fluid and cytokine production in whole blood were measured to assess pulmonary efficacy versus systemic efficacy. PK/PD characterization of fluticasone with various formulations in the rat inflammation model provided an integrated approach in preclinical to evaluate lung targeted efficacy for ICS. Our study concluded that the combination of the rat LPS model and fluticasone is not suitable to use for establishing potency and dose requirement for new drug candidate designed for topical only efficacy.