Serum level, half-life and apparent volume of distribution of doxycycline in geriatric patients.

The serum level, half-life and apparent volume of distribution of doxycycline were determined in geriatric patients. The serum level and apparent volume of distribution were higher than those reported for younger persons. The apparent volume of distribution was correlated with the serum iron and beta-globulin levels. The possible influence of binding of doxycycline to serum iron on its pharmacokinetics is discussed.