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Administration, Inhalation, Animals, Anti-Asthmatic Agents, Asthma, Biological Transport, Cell Line, Cell Membrane Permeability, Disease Models, Animal, Drug Compounding, Drug Delivery Systems, Drug Stability, Electric Impedance, Enzyme-Linked Immunosorbent Assay, Guinea Pigs, Humans, Liposomes, Male, Respiratory Mucosa, Secretory Leukocyte Peptidase Inhibitor


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PURPOSE: Inhaled recombinant Secretory Leukocyte Protease Inhibitor (rSLPI) has shown potential for treatment of inflammatory lung conditions. Rapid inactivation of rSLPI by cathepsin L (Cat L) and rapid clearance from the lungs have limited clinical efficacy. Encapsulation of rSLPI within 1,2-Dioleoyl-sn-Glycero-3-[Phospho-L-Serine]:Cholesterol liposomes (DOPS-rSLPI) protects rSLPI against Cat L inactivation in vitro. We aimed to determine the effect of liposomes on rSLPI pharmacokinetics and activity in vitro and after local delivery to the airways in vivo.

METHODS: Transport of DOPS-rSLPI and free-rSLPI across a polarised air-liquid epithelial monolayer was measured. An asthma guinea pig model was administered either DOPS-rSLPI liposomes or free-rSLPI by intratracheal instillation.

RESULTS: Apparent permeability (P(app)) of free-rSLPI was significantly higher at 4.9 x 10⁻⁶ cm/s than for DOPS-rSLPI, P(app) of 2.05 x 10⁻⁷ cm/s, confirmed by in vivo studies. Plasma rSLPI concentrations were highest in free-rSLPI-treated animals compared with those treated with DOPS-rSLPI; there also appeared to be a trend for higher intracellular rSLPI content in animals dosed with DOPS-rSLPI compared to free-rSLPI. Eosinophil influx was recorded as a measure of inflammation. Pre-dosing with either free-rSLPI or DOPS-rSLPI prevented inflammatory response to antigen challenge to levels comparable to control animals.

CONCLUSION: Encapsulation of rSLPI in DOPS:Chol liposomes improves stability, reduces clearance and increases residence time in the lungs after local delivery.


Pharmacy and Pharmaceutical Sciences


Gibbons A, Padilla-Carlin D, Kelly C, Hickey A, Taggart C, McElvaney NG, Cryan SA. The effect of liposome encapsulation on the pharmacokinetics of recombinant secretory leukocyte protease inhibitor (rSLPI) therapy after local delivery to a guinea pig asthma model. Pharmaceutical Research. 2011;28(9):2233-45.

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