Possible Interaction: Calcium Carbonate and Ciprofloxacin

“Co-administration of 500 mg/L CaCO3 to healthy volunteers significantly reduced the urinary excretion of 250 mg/L ciprofloxacin but not 200 mg/L ofloxacin although neither the fraction of absorbed dose nor the half-lives were markedly affected.”

“In intestinal sacs, the presence of 5000 mg/L CaCO3 significantly reduced both the absorption constant and the fraction of absorbed dose of 2000 mg/L ciprofloxacin but not 2000 mg/L ofloxacin.”

“When the same concentration of CaCO3 was introduced into the isolated intestinal segments of rats, the absorption of both 200 mg/L ofloxacin and 400 mg/L ciprofloxacin was reduced significantly from 49% and 35% respectively to approximately 30% in each case.”

“BACKGROUND The oral bioavailability of ciprofloxacin is significantly decreased when administered with calcium carbonate.”

“The relative bioavailability of Cipro when given with calcium carbonate was approximately 60% of the control value.”

“There was a mean reduction of 40% in Cmax and 43% in AUC when calcium carbonate was administered with ciprofloxacin , compared with ciprofloxacin alone (P < 0.05).”

“Further, an in vitro crystallization assay showed that PfX could alter the CaCO3 morphologies of both calcite and aragonite polymorphs.”

“These results suggest that matrix protein PfX might regulate CaCO3 morphology via selective binding and inhibit the growth of certain crystal faces, providing new clues for understanding biomineralization mechanisms in mollusk.”

“It was found that reduced ciprofloxacin absorption in the presence of aluminium hydroxide, calcium carbonate or multivitamins/zinc was accounted for by reduced drug solubility.”