Effect of iron on the absorption and distribution of clodronate after oral administration in rats

The effect of iron on the absorption and distribution of disodium clodronate in rats after oral administration was studied. Disodium clodronate (300 mg/25 microCi/kg) was given both alone and with an equivalent amount of ferrous sulphate. The radioactivity in plasma and various tissue was measured. Concentration of clodronate in plasma was also determined with the GC-mass-selective detection method and the values compared with those measured with the isotope method. After administration, clodronate was rapidly cleared from plasma. Most of the dose was taken up by bone and only small amounts were found in non-calcified tissues. Concurrent ingestion of iron caused a marked decrease in the absorption of clodronate.