Effect of Maalox on the oral absorption of sparfloxacin

Sparfloxacin is a broad-spectrum oral fluoroquinolone antimicrobial agent w ith a long elimination half-life (t(1/2)). Concurrent treatment with antaci ds has demonstrated a reduction in the oral absorption of many quinolones. This study was undertaken to determine an optimal time for dosing antacids in relation to sparfloxacin administration to minimize antacid-induced redu ction in sparfloxacin bioavailability. This open-label, single-dose, random ized, four-way crossover study was conducted in 20 healthy male volunteers between the ages of 18 and 38 years. Treatments consisted of single 400-mg oral doses of sparfloxacin alone and with Maalox(R) 30 mL given 2 hours bef ore, 2 hours after, and 4 hours after oral administration of sparfloxacin. All 20 subjects completed the study. A 400-mg single oral dose of sparfloxa cin was well tolerated both given alone and with Maalox. Maalox given 4 hou rs after sparfloxacin administration was the only regimen that did not caus e a statistically significant reduction in the rate and extent of sparfloxa cin absorption. The 90% confidence intervals comparing sparfloxacin alone w ith the preceding regimen in terms of area under the concentration-time cur ve from zero to infinity (AUC(0-infinity)) and maximum plasma concentration (C-max) were within the range 80% to 125%. Administration of Maalox 2 hour s before, 2 hours after, and 4 hours after sparfloxacin caused mean decreas es in AUC(0-infinity) of 23%, 17%, and 5%, respectively. Corresponding decr eases in mean C-max values were 29% with Maalox administered 2 hours before sparfloxacin and 13% with Maalox administered 2 hours after sparfloxacin. The mean C-max value was unaffected when Maalox was administered 4 hours af ter sparfloxacin administration. The 90% confidence intervals for these com parisons with sparfloxacin alone were outside the 80% to 125% range and did not include 100%. Time to C-max and t(1/2) were similar for all four regim ens. The elimination rate of sparfloxacin was unaffected by concomitant adm inistration with Maalox in healthy male volunteers.