Drug Interaction Report

Netilmicin and Penicillin V Potassium: Interaction Details

A pharmacist-reviewed analysis of the Netilmicin and Penicillin V Potassium interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 9, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Penicillin V Potassium

Beepen-VK® Betapen-VK® Ledercillin VK® Pen-Vee K® Penapar-VK® Uticillin VK® V-Cillin K® Veetids®
+

Netilmicin

No brand names on record
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 9, 2026
Editorial policy · Data sources
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Interaction severity
Minor
Usually limited clinical impact.
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.

Of 15 documented Netilmicin interactions, 6 are rated minor — including this one.
Onset
rapid
Evidence
probable
Severity
Minor

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 Netilmicin and Penicillin V Potassium together?

Loss of aminoglycoside efficacy Always confirm with your pharmacist or prescriber before making any change.

How serious is the Netilmicin and Penicillin V Potassium 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 Netilmicin or Penicillin V Potassium 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)

  1. 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
  2. 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
  3. 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
  4. 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.
  5. Davies M, Morgan JR, & Anand C: Interactions of carbenicillin and ticarcillin with gentamicin. Antimicrob Agents Chemother 1975; 7:431-434. PubMed
  6. Riff L & Jackson GG: Laboratory and clinical conditions for gentamicin inactivation by carbenicillin. Arch Intern Med 1972; 130:887-891. DOI
  7. Eykyn S, Phillips I, & Ridley M: Gentamicin plus carbenicillin. Lancet 1971; 1:545-546. PubMed
  8. McLaughlin JE & Reeves DS: Clinical and laboratory evidence for inactivation of gentamicin by carbenicillin. Lancet 1971a; 1:261-264. DOI
  9. McLaughlin JE & Reeves DS: Gentamicin plus carbenicillin. Lancet 1971b; 1:864. PubMed
  10. Noone P & Pattison JR: Therapeutic implications of interaction of gentamicin and penicillins. Lancet 1971; 2:575-578. DOI
  11. Riff L & Jackson GG: Gentamicin plus carbenicillin. Lancet 1971; 1:592. PubMed
  12. Farchione LA: Inactivation of aminoglycosides by penicillins. J Antimicrob Chemother 1981; 8:27-36. PubMed
  13. Jorgensen JH & Crawford SA: Selective inactivation of aminoglycosides by newer beta-lactam antibiotics. Curr Ther Res Clin Exp 1982; 32:25-35.
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Penicillin V Potassium

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Beyond drug–drug

These medications also interact with supplements

Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:

Penicillin V Potassium + Activated Charcoal Asarabacca Siberian Cocklebur Aristolochia Bacillus Coagulans Bacillus Subtilis Bifidobacterium Animalis Subsp. Lactis Bifidobacterium Bifidum + 48 more
Netilmicin + Asarabacca Siberian Cocklebur Aristolochia Bacillus Coagulans Bacillus Subtilis Bifidobacterium Animalis Subsp. Lactis Bifidobacterium Bifidum Bifidobacterium Breve + 27 more

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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.