Aluminum Carbonate, Basic and Gemifloxacin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Gemifloxacin
Aluminum Carbonate, Basic
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Decreased oral gemifloxacin effectiveness
Interaction Deep Dive
The administration of gemifloxacin 320 mg 10 minutes before dosing with an aluminum- and magnesium-containing antacid (Maalox(R)) resulted in a marked decrease in the oral bioavailability of gemifloxacin. This decrease in bioavailability was similar to the reductions seen with other oral fluoroquinolones and antacid. Oral gemifloxacin should be given at least two hours before or three hours after an aluminum- and magnesium-containing antacid231.
Why it happens (mechanism)
Decreased gemifloxacin absorption due to chelation
Literature reports
2 reports — tap to read
a) Fourteen healthy male volunteers were evaluated during an open, randomized, single-dose, four-way crossover study to determine the effect of antacid administration on gemifloxacin bioavailability. The four treatment phases were separated by a washout period of at least six days and consisted of the following: gemifloxacin 320 mg given three hours after Maalox(R) 20 mL, gemifloxacin 320 mg given 10 minutes before Maalox(R) 20 mL, gemifloxacin 320 mg given two hours before Maalox(R) 20 mL, and gemifloxacin 320 mg given alone. When gemifloxacin was given 10 minutes before Maalox(R), the mean area under the concentration-time curve (AUC) was decreased by 85% and the maximum concentration (Cmax) was reduced by 87%. The administration of gemifloxacin three hours after Maalox(R) resulted in only a modest decrease in gemifloxacin bioavailability (AUC decreased by 15% and Cmax decreased by 17%). Gemifloxacin given two hours before Maalox(R) did not cause a significant alteration in gemifloxacin bioavailability. It is therefore recommended that gemifloxacin be administered at least two hours before or three hours after an aluminum- and magnesium-containing antacid 1.
b) Simultaneous coadministration of calcium carbonate reduces the maximum plasma concentration (Cmax) and area under the concentration-time curve (AUC) of gemifloxacin significantly. Sixteen healthy volunteers participated in the study. In a four-way crossover design study volunteers received the following drug combinations in random order: (A) gemifloxacin (oral) alone, (B) gemifloxacin 2 hours after calcium, (C) gemifloxacin simultaneously with calcium (oral), and (D) gemifloxacin administered 2 hours before calcium. Simultaneous administration of calcium carbonate with gemifloxacin 320 mg resulted in a modest reduction in bioavailability of gemifloxacin (average decrease of 21% for AUC and 17% for Cmax), compared to gemifloxacin alone (p less than 0.05). In contrast, administration of calcium carbonate either 2 hours before or after dosing with gemifloxacin 320 mg resulted in only a minor decrease of gemifloxacin bioavailability (average decrease of 7% for the 2 hours before and 5% when gemifloxacin was administered 2 hours after), compared to that observed with gemifloxacin given alone. The results of this study demonstrate that simultaneous coadministration of calcium carbonate 1000 mg reduces the bioavailability of gemifloxacin 2.
Common questions
Can I take Aluminum Carbonate, Basic and Gemifloxacin together?
Decreased oral gemifloxacin effectiveness Always confirm with your pharmacist or prescriber before making any change.
How serious is the Aluminum Carbonate, Basic and Gemifloxacin interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Aluminum Carbonate, Basic or Gemifloxacin need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (3)
- Allen A, Vousden M, Porter A, et al: Effect of Maalox(R) on the bioavailability of oral gemifloxacin in healthy volunteers. Chemotherapy 1999; 45:504-511.
- Pletz M, Petzold P, Allen A, et al: Effect of calcium carbonate on bioavailability of orally administered gemifloxacin. Antimicrob Agents Chemother 2003; 47:2158-2160. PubMed
- Product Information: Factive(R), gemifloxacin mesylate tablets. Genesoft Pharmaceuticals, San Francisco, CA, 2003. DailyMed
Keep reading about Gemifloxacin
Keep reading about Aluminum Carbonate, Basic
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