“…The following morning, subjects were given a single oral dose of 10-mg racemic amlodipine (Norvasc, Pfizer Pharmaceutical, Seoul, Korea). Blood samples were collected immediately prior to drug administration (baseline) and then at 1,2,3,4,5,6,7,8,9,10,12,24,48,72,96,120,144, and 168 h after drug administration. Blood samples were collected in heparinized tubes (Vacutainer; Becton Dickinson, Franklin Lakes, NJ) after discarding 1 ml of blood.…”