Change in Blood Kinin and Plasma Porcine Pancreatic Kallikrein Concentrations after Oral Administration of Kallikrein Formulation in Dog

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Oral formulation of tissue kallikrein consists primarily of porcine pancreatic kallikrein (PPK) and is used to improve peripheral circulation, menopausal symptoms, and impaired chorioretinal circulation. Although gastrointestinal absorption of tissue kallikrein after oral administration has been reported in nonclinical and clinical studies, the increase in the concentration of pharmacologically active kinins, which are produced from kininogens by tissue kallikrein, has not been investigated. In this study, kallikrein formulation was orally administered to dogs and an increase in PPK in plasma was confirmed, along with an increase in the blood kinin level. After oral administration of kallikrein formulation (10 U/kg or 20 U/kg PPK) to dogs, PPK concentration in plasma reached maximum 3 h after administration, and then decreased time-dependently. The maximum concentration was 6.01±1.44 pg/ml in the 10 U/kg group and 10.88±3.59 pg/ml in the 20 U/kg group (mean±S.E.M, n=5). After oral administration of kallikrein formulation (40 U/kg PPK) to dogs, the blood kinin concentration in the PPK-treated group was significantly increased 2 h after administration as compared to the purified water-treated group (before administration: 48.8±2.1 ng/ml vs. 48.1±1.9 ng/ml, 2 h after administration: 55.5±1.6 ng/ml vs. 49.6±1.4 ng/ml; mean±S.E.M, n=4, p<0.05). In conclusion, PPK was considered to be absorbed after oral administration and to exert its pharmacological action via kinins produced by kininogen degradation in dogs.