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Determination of amikacin stability at 1% and 3% concentrations in four topical solutions over a 56-day period
Arden M Klinczar1, Joel D Griffies1, Fiona L Bateman1
1Animal Dermatology Clinic, Marietta, GA, 30067, USA.
Background:
Anecdotally, amikacin has been added to compounded topical preparations for the management of canine bacterial otitis externa. However, the stability of amikacin within these solutions is unknown.
Hypothesis/Objectives:
The purpose of this study was to determine the stability of amikacin at 10 and 30 mg/mL concentrations in four topical solutions over a 56 day period. We hypothesised that amikacin would maintain chemical stability within the various solutions.
Methods And Materials:
Amikacin was formulated to 10 and 30 mg/mL (1% and 3%) concentrations within four topical solutions: tris-EDTA (TrizEDTA Aqueous Flush) (TE); 0.15% chlorhexidine gluconate and tris-EDTA (TrizCHLOR Flush) (TC); 0.9% NaCl (NA); and 0.9% NaCl + 2 mg/mL dexamethasone (ND). Samples were made in duplicate and stored at room temperature (25°C) for 0, 7,14, 21, 28 and 56 days. Amikacin content was quantified, in triplicate, by ultrahigh-performance liquid chromatography tandem mass spectrometry.
Results:
The recovered amikacin concentrations for the 10 mg/mL solutions ranged from 10 to 13.5 mg/mL (mean 11.5 mg/mL) with the exception of NA sample 2 at Day (D)0 (9.4 mg/mL) and D7 (9.2 mg/mL). The recovered amikacin concentrations for the 30 mg/mL solutions ranged from 30 to 40.2 mg/mL (mean 35.7 mg/mL). No significant difference was seen between the amikacin concentrations at D0 compared to D56 for all solutions except 10 mg/mL TE (P < 0.001).
Conclusions And Clinical Relevance:
Amikacin maintained stability within TE, TC, NA and ND over 56 days except when formulated at 10 mg/mL within TE.
Insights
Amikacin stability in topical ear solutions for dogs was assessed. Amikacin remained stable in most formulations over 56 days, except for one specific concentration in tris-EDTA.
Area of Science:
- Veterinary Pharmacology
- Drug Stability Studies
- Canine Otic Preparations
Background:
- Topical amikacin is anecdotally used for canine bacterial otitis externa.
- The chemical stability of amikacin in compounded topical solutions is not well-documented.
Purpose of the Study:
- To determine amikacin stability in four topical solutions at 10 and 30 mg/mL over 56 days.
- To evaluate amikacin's chemical integrity in common otic formulations.
Main Methods:
- Amikacin was formulated at 10 and 30 mg/mL in tris-EDTA, chlorhexidine/tris-EDTA, saline, and saline/dexamethasone solutions.
- Samples were stored at room temperature and analyzed over 56 days using ultrahigh-performance liquid chromatography tandem mass spectrometry.
Main Results:
- Amikacin generally maintained stability across tested concentrations and solutions over 56 days.
- Recovered concentrations ranged from 10-13.5 mg/mL (10 mg/mL formulations) and 30-40.2 mg/mL (30 mg/mL formulations).
- A significant decrease in amikacin concentration was observed only in the 10 mg/mL tris-EDTA formulation.
Conclusions:
- Amikacin demonstrated good chemical stability in most tested topical solutions for canine otitis externa management.
- Formulation at 10 mg/mL in tris-EDTA was an exception, showing reduced stability over 56 days.
- These findings support the use of amikacin in specific compounded otic preparations for dogs.
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