How are pharmacokinetics of aspirin?

When given orally, aspirin is absorbed by passive diffusion and quickly hydrolyzed to salicylic acid in the liver. Salicylic acid is further metabolized in the liver, and some is excreted unchanged in the urine. The half-life of aspirin ranges from 15 to 20 minutes and for salicylic acid is 3 to 12 hours.