Effective penetration of doxycycline into the serum and aqueous humor.

Twenty-five human subjects of both sexes undergoing operations for senile cataract were selected for the present study. Doxycycline was administered orally and at various intervals its penetration into the serum and aqueous humor were determined. It was concluded that for achieving therapeutic concentrations in the serum, doxycycline can be given in the dosage of 200 mg on the first day followed by 100 mg every 24 hours. However, in order to achieve therapeutic concentrations in the aqueous humor, doxycycline should be administered in the dosage of 200 mg on the first day followed by 100 mg every 12 hours.