Pharmacokinetic investigations in adult humans after parenteral administration of the lysine salt of acetyl-salicylic acid.

The lysine salt of acetylsalicylic acid was administered intravenously to four volunteers and intramuscularly to three of them. The drug was tolerated without any observed side effects. Immediately after intravenous application most of the plasma salicylate was acetylsalicylic acid. The highest concentration of acetylsalicylic acid was found after 2 minutes, highest levels of salicylic acid after 60 minutes. Elimination of acetylsalicylic acid was relatively quick within the first period after intravenous administration according to a half-life of 8 minutes. Half-life of salicylic acid was determined to be 3 hours. Intramuscular application results in a constant blood level for a longer period. Bioavailability of acetylsalicylic acid was slightly lower after intramuscular application than after intravenous administration.