Feasibility of tissue plasminogen activator formulated for pulmonary delivery.
OBJECTIVE
This study was conducted to assess the feasibility of a pulmonary formulation of tissue plasminogen activator (tPA) for nebulization into the airway by measuring protein stability, biologic activity, particle size, and estimating human lung distribution.


METHODS
Formulations were derived by varying the surfactant and protein concentrations. Protein stability and recovery of each nebulized tPA formulation were assessed by ultraviolet spectroscopy. Formulations that met protein stability feasibility criteria were assessed for biologic and fibrinolytic activities. Biologic activity was determined by their ability to inhibit superoxide anion production by human neutrophils. Fibrinolytic activity was assessed by the cleavage of plasminogen to plasmin. Aerodynamic properties were assessed using a cascade impactor, and an estimation of human airway deposition was made via a human lung replica.


RESULTS
Twenty-seven tPA formulations were initially assessed, 15 of which met protein stability criteria. Subsequently, three of these formulations maintained biologic and fibrinolytic activities. These formulations exhibited particle sizes of 2.4-3.1 microm, and had respirable doses > or =65%. A formulation of 1mg mL(-1) tPA and 0.1% Tween 80 exhibited a 45% deposition in the lower airways of a human lung replica.


CONCLUSIONS
A suitable pulmonary tPA formulation was identified that, following nebulization, maintained protein stability as well as biologic and fibrinolytic activities, and resulted in an optimal respirable dose and human airway deposition. This formulation may be applicable in the treatment of lung diseases, such as acute respiratory distress syndrome by permitting targeted pulmonary delivery of a therapeutic protein to the lungs.
Dunn
John S
JS
Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
Nayar
Rajiv
R
Campos
Jackie
J
Hybertson
Brooks M
BM
Zhou
Yue
Y
Manning
Mark Cornell
MC
Repine
John E
JE
Stringer
Kathleen A
KA
D002626:Chemistry, Pharmaceutical; D016503:Drug Delivery Systems; D004795:Enzyme Stability; D005240:Feasibility Studies; D005343:Fibrinolytic Agents / Q000008:administration & dosage / Q000378:metabolism; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D011652:Pulmonary Circulation; D012123:Pulmonary Ventilation; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D010959:Tissue Plasminogen Activator / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism*
D005343:Fibrinolytic Agents; D011994:Recombinant Proteins; D010959:Tissue Plasminogen Activator