Effect of multiple staggered doses of calcium on the bioavailability of ciprofloxacin.
OBJECTIVE
To determine the effect on the relative bioavailability (Fr) of a staggered single dose of ciprofloxacin given two hours after a morning dose of calcium carbonate given three times daily over the three previous days.


METHODS
Thirteen male volunteers participated in this randomized, nonblinded, crossover investigation; 12 subjects were included in the final analysis.


METHODS
Data collection and ciprofloxacin administration occurred at Albany Medical Center, a tertiary-care teaching institution. Calcium carbonate administration was on an outpatient basis.


RESULTS
For 12 volunteers, the mean +/- SD Fr of ciprofloxacin staggered with calcium was 0.87 +/- 0.23 (noncompartmental model) and 0.98 +/- 0.27 (compartmental model). Other statistically significant findings were a decrease in the time to maximum concentration of ciprofloxacin staggered with calcium in serum compared with ciprofloxacin alone (from 1.76 +/- 0.54 to 1.23 +/- 0.52 h in the noncompartmental model; p < 0.05), and a decrease in the same parameter (from 1.92 +/- 0.96 to 0.77 +/- 0.53 in the compartmental model; p < 0.005). Maximum concentration of ciprofloxacin staggered with calcium was decreased in the noncompartmental model compared with ciprofloxacin alone (from 2.11 +/- 0.72 to 1.60 +/- 0.33, respectively; p < 0.05). The elimination half-life and area under the concentration-time curve of ciprofloxacin were not significantly altered.


CONCLUSIONS
Repeated doses of calcium carbonate, administered two hours before ciprofloxacin, did not significantly alter the Fr of this fluoroquinolone.
Lomaestro
B M
BM
Albany Medical Center, Department of Pharmacy, NY 12208.
Bailie
G R
GR
D000293:Adolescent; D000328:Adult; D001682:Biological Availability; D002119:Calcium Carbonate / Q000008:administration & dosage*; D002939:Ciprofloxacin / Q000008:administration & dosage / Q000493:pharmacokinetics*; D004334:Drug Administration Schedule; D006801:Humans; D008297:Male; D008875:Middle Aged; D013997:Time Factors
D002939:Ciprofloxacin; D002119:Calcium Carbonate