Effects of tetracycline on the absorption of 65Zinc in rats

Summary The effects of tetracycline on the absorption of orally ingested ⁶⁵Zn was studied on rats by whole body counting assay. ⁶⁵Zn was given as a single dose to groups of rats, five in each, which were started on tertracycline. Tetracycline was given in daily doses of 25 mg, 50 mg, 100 mg, and 200 mg for 10 days. From the 6th day of the study, ⁶⁵Zn retention when plotted against time in a semilog plot, approximated linearity. The net absorption of ⁶⁵Zn in the various groups was determined by extrapolating to zero time the linear curve segment of individual retention curves. Except for the lowest tetracycline dosage, tetracycline significantly impaired ⁶⁵Zn absorption. The elimination rate of retained ⁶⁵Zn from the 6th day was significantly higher in the group receiving 200 mg tetracycline as compared with the control group.