According to the result of the pharmacokinetic examination of T-2588 (esterified prodrug of T-2525) administered to adult male volunteers who have undergone gastrectomy, it appears that the absorption of T-2588 is delayed in the hypoacidity or the anacidity and also the excretion ratio of T-2525A (an inactive metabolite of T-2525) showed a tendency to become higher in these subjects. Again, according to the result of the pharmacokinetic examination of T-2588 when it was administered together with probenecid to normal healthy volunteers, it appears that the T-2525 is excreted from the kidneys not only into the glomerular filtration but also partly through renal tubules.