Introduction: The use of conventional methods of drug administration during antibiotic therapy of critically ill patients may be insufficient since the minimum inhibitory concentration required for effective therapy may not be maintained for the required amount of time due to the peculiarities of the patients’ pharmacokinetics. Endolymphatic therapy has been proposed as an alternative approach.

Aim: The evaluation of meropenem pharmacokinetics during endolymphatic antibiotic therapy and its comparison to intravenous administration route.

Materials and methods: The blood samples from patients treated with meropenem endolymphatically (n = 1) and intravenously (n = 1) were analyzed using high-performance liquid chromatography with diode-array detection and high-performance liquid chromatography with electrospray ionization tandem mass-spectrometry.

Results: In intravenous and endolymphatic administration of meropenem minimum plasma concentration at steady state was 10 µg/ml and 16.39 µg/ml, maximum plasma concentration at steady state – 42.41 µg/ml and 42.57 µg/ml, area under the curve at steady state – 363.997 µg·h·ml-1 and 521.86 µg·h·ml-1, mean residence time – 8.446 and 11.365 hours.

Conclusion: Our results demonstrate longer persistence of meropenem in circulation after endolymphatic administration thus indicating preferable pharmacokinetics. Additionally, minimum plasma concentration at steady state after endolymphatic treatment remained at a high level, exceeding minimum inhibitory concentration. However, further studies in larger cohorts are required for obtaining reliable confirmations of endolymphatic administration route benefits.