Ampicillin Injection and Kanamycin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Ampicillin Injection
Kanamycin
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
Loss of aminoglycoside efficacy
Interaction Deep Dive
Concomitant penicillin and aminoglycoside therapy has been reported to result in inactivation of the aminoglycoside both in vivo and in vitro. Amikacin appears to possess the greatest stability in the presence of penicillins; the half-life of amikacin is minimally affected by the presence of carbenicillin. It appears that, in the treatment of severely ill patients requiring both penicillin and aminoglycoside therapy, amikacin is the aminoglycoside of choice1213.
Why it happens (mechanism)
Chemical inactivation of the aminoglycoside
Literature reports
1 report — tap to read
a) Although penicillins and aminoglycosides are often used in combination for their synergistic effect, a number of reports have shown that a high penicillin to aminoglycoside ratio (greater than 50:1) for a prolonged period of time results in chemical inactivation of both compounds 1234567891011. This seems to occur in vitro when both drugs are physically mixed together, and in vivo in patients with poor renal function where renal excretion of the drugs is delayed.
Common questions
Can I take Ampicillin Injection and Kanamycin together?
Loss of aminoglycoside efficacy Always confirm with your pharmacist or prescriber before making any change.
How serious is the Ampicillin Injection and Kanamycin interaction?
It is rated minor. Usually limited clinical impact.
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 Ampicillin Injection or Kanamycin 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 (13)
- Blair DC, Duggan DO, & Schroeder ET: Inactivation of amikacin and gentamicin by carbenicillin in patients with end-stage renal failure. Antimicrob Agents Chemother 1982; 22:376-379. PubMed
- Pickering LK & Gearhart P: effect of time and concentration upon interaction between gentamicin, tobramycin, netilmicin, or amikacin and carbenicillin or ticarcillin. Antimicrob Agents Chemother 1979; 15:592-596. DOI
- Ervin FR, Bullock WE Jr, & Nuttall CE: Inactivation of gentamicin by penicillins in patients with renal failure. Antimicrob Agents Chemother 1976; 9:1004-1011. PubMed
- Weibert R, Keane W, & Shapiro F: Carbenicillin inactivation of aminoglycosides in patients with severe renal failure. Trans Am Soc Artif Intern Organs 1976; 22:439-443.
- Davies M, Morgan JR, & Anand C: Interactions of carbenicillin and ticarcillin with gentamicin. Antimicrob Agents Chemother 1975; 7:431-434. DOI
- Riff L & Jackson GG: Laboratory and clinical conditions for gentamicin inactivation by carbenicillin. Arch Intern Med 1972; 130:887-891. DOI
- Eykyn S, Phillips I, & Ridley M: Gentamicin plus carbenicillin. Lancet 1971; 1:545-546. PubMed
- McLaughlin JE & Reeves DS: Clinical and laboratory evidence for inactivation of gentamicin by carbenicillin. Lancet 1971a; 1:261-264. DOI
- McLaughlin JE & Reeves DS: Gentamicin plus carbenicillin. Lancet 1971b; 1:864. PubMed
- Noone P & Pattison JR: Therapeutic implications of interaction of gentamicin and penicillins. Lancet 1971; 2:575-578. DOI
- Riff L & Jackson GG: Gentamicin plus carbenicillin. Lancet 1971; 1:592. PubMed
- Farchione LA: Inactivation of aminoglycosides by penicillins. J Antimicrob Chemother 1981; 8:27-36. DOI
- Jorgensen JH & Crawford SA: Selective inactivation of aminoglycosides by newer beta-lactam antibiotics. Curr Ther Res Clin Exp 1982; 32:25-35.
Keep reading about Ampicillin Injection
Keep reading about Kanamycin
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