[Vitamin K 1 concentration and vitamin K-dependent clotting factors in newborn infants after intramuscular and oral administration of vitamin K 1].

Serum concentration of vitamin K1 and activity of vitamin-K-dependent factors II, VII, IX and X were determined before and after vitamin K1 administration in infants. The babies received vitamin K1 intramuscularly or orally. 12 hours after vitamin K1 treatment the mean concentration was increased in the groups receiving vitamin K1 intramusculary or orally, respectively. Serum level of vitamin K1 fell exponentially, the mean half life was about 30 hours in both groups. Activity of vitamin K-dependent clotting factors did not change significantly after intramuscular or oral vitamin K1 administration during the first four-five days of life. It was no direct correlation between the concentration of vitamin K1 and the activity of vitamin-K-dependent clotting factors. This study suggest that oral administration of vitamin K1 is as effective as the intramuscular route.