Lack of bioequivalence of gatifloxacin when coadministered with calcium-fortified orange juice in healthy volunteers

Previous work has demonstrated that the chelation interaction seen with ciprofloxacin when it is coadministered with antacids also happens when it is coadministered with calcium-fortified foods. This study was conducted to study whether this was a drug-specific finding or whether the interaction occurs with other members of the fluoroquinolone class of drugs. Sixteen healthy volunteers received single 400mg oral doses of gatifloxacin with 12 ounces each of Water, nonfortified orange juice, and calcium-fortified orange juice and had plasma samples drawn for assay over the subsequent 48 hours. Results demonstrated significant increases in total oral clearance (15%) and volume of distribution (13%) along with a matching significant decrease (12%) in exposure (AUC) when gatifloxacin was taken with the fortified juice.