Effects of ascorbic acid on interactions between ciprofloxacin and ferroussulphate, sodium ferrous citrate or ferric pyrophosphate, in mice

The absorption of ciprofloxacin has been reported to be impaired by concomi tant administration of ferrous sulphate. The effects of sodium ferrous citr ate and ferric pyrophosphate, which have been used as extensively as ferrou s sulphate, on the absorption of ciprofloxacin were compared with that of f errous sulphate. The effects of ascorbic acid on the interactions between c iprofloxacin and each iron compound were studied in mice. Mice were treated orally with ciprofloxacin (50mg kg(-1)) alone, the iron compound (ferrous sulphate, sodium ferrous citrate or ferric pyrophosphate; 50mg elemental ir on kg(-1)) alone, ciprofloxacin with each iron compound or ciprofloxacin in combination with each iron compound and ascorbic acid (250 mg kg(-1)). The maximum serum concentration of ciprofloxacin was significantly (P < 0.0 1) reduced from 1.15+/-0.11 mu g mL(-1) (ciprofloxacin alone) to 0.17+/-0.0 1, 0.27+/-0.01 or 0.28+/-0.02 mu g mL(-1), respectively, when ferrous sulph ate, sodium ferrous citrate or ferric pyrophosphate was administered along with ciprofloxacin. The addition of ascorbic acid did not affect the inhibi tory effects of each iron compound on the absorption of ciprofloxacin. Cipr ofloxacin did not affect the variation of serum iron levels after administr ation of each iron compound. The addition of ascorbic acid significantly (P < 0.01) enhanced the increase in serum iron concentration after administra tion of sodium ferrous citrate, showing an increase from 270+/-6 mu g dL(-1 ) to 463+/-11 mu g dL(-1) compared with an increase from 248+/-8 mu g dL(-1 ) to 394+/-18 mu g dL(-1) after administration of sodium ferrous citrate al one. Ascorbic acid also caused a significant (P < 0.01) increase in serum i ron concentration from 261+/-16 mu g dL(-1) to 360+/-12 mu g dL(-1) after a dministration of ferric pyrophosphate, although it did not affect the level s after ferrous sulphate administration. The results suggest that sodium ferrous citrate and ferric pyrophosphate sh ould not be administered with ciprofloxacin (as for ferrous sulphate) and t hat sodium ferrous citrate is converted to the ferric form more easily than ferrous sulphate. This difference in convertibility might contribute to a clinical difference between sodium ferrous citrate and ferrous sulphate.