A new route of heparin administration--the lung.

Instillation of a single dose of heparin into the lungs of the dog resulted in a steady prolonged hypocoagulability as measured by the Lee and White clotting time, partial thromboplastin and activated partial thromboplastin times. 15 mg of heparin/kg increased clotting time three to five times control values. The anticoagulant effect occurred within one hour and lasted 48 h or more, in contrast to the short effect of intravenous heparin. For doses of 8, 10, 12, 15 and 20 mg/kg, there was a corresponding increase in the area under the response curve. The very prolonged moderate anticoagulant state with intrapulmonary heparin did not show the wide fluctuations in coagulation test values which occur with intravenous heparin.