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The shelf life of antimicrobial ear drops

Matthew P A Clark1, Lyela Pangilinan, Amy Wang

  • 1Division of Otolaryngology, Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada.

The Laryngoscope
|December 17, 2009
PubMed
Abstract

Insights

Antimicrobial ear drops containing gentamicin or ciprofloxacin remain effective and uncontaminated for at least four months after opening. This supports advising patients to keep unfinished ear drops for future use, offering economic benefits.

Area of Science:

  • Otolaryngology
  • Microbiology
  • Pharmacology

Background:

  • Current recommendations for antimicrobial ear drop shelf life lack empirical evidence.
  • Topical otic solutions are frequently prescribed for otorrhea.

Purpose of the Study:

  • To determine appropriate shelf-life recommendations for antibiotic-containing ear drops.
  • To assess the stability and sterility of common antimicrobial otic solutions.

Main Methods:

  • Prospective experimental study design.
  • Effectiveness testing of gentamicin and ciprofloxacin ear drops against Staphylococcus aureus and Pseudomonas aeruginosa using agar plates.
  • Assessing bottle teat and drop solution contamination after patient use.

Main Results:

  • No loss of antibiotic effectiveness observed over a 4-month period.
  • No microbial contamination detected on bottle teats of drops used by patients with otorrhea.
  • No contamination of ear drop solutions found after 4 months of use.

Conclusions:

  • Antimicrobial ear drops with gentamicin or ciprofloxacin maintain efficacy and sterility for at least 4 months post-opening.
  • Findings suggest extended usability for patients, potentially including other antimicrobial drops.
  • Supports advising patients to retain unused ear drops for future therapeutic needs, enhancing cost-effectiveness.

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