Gentamicin delivery to the inner ear: Does endolymphatic hydrops matter?
Marques P (1,2), Duan M (3,4), Perez-Fernandez N (5), Spratley J (1,2,6).
(1) Department of Otorhinolaryngology, S.João Hospital Centre, Porto, Portugal.
(2) Unit of Otorhinolaryngology, Department of Surgery and Physiology, University of Porto Medical School, Porto, Portugal.
(3) Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.
(4) Department of Otolaryngology, Head and Neck Surgery, Karolinska Universisty Hospital, Karolinska Institutet, Stockholm, Sweden.
(5) Department of Otorhinolaryngology, Clinica Universidad de Navarra, Madrid, Spain.
(6) Center for Health Technology and Services Research (CINTESIS), University of Porto Medical School, Porto, Portugal.
Middle ear application of gentamicin is a common medical treatment for uncontrolled Ménière's disease. The objective of the study was to evaluate the impact of endolymphatic hydrops on inner ear delivery.
Perilymph gentamicin concentrations and correlation with endolymphatic hydrops in an animal model were assessed. A group of 24 guinea pigs was submitted to surgical obstruction of the endolymphatic sac and duct of the right ear. Gentamicin was applied either to the right ear's round window niche or through a transtympanic injection. Perilymph specimens were collected at different times. Histologic morphometry was used to evaluate both turn-specific and overall hydrops degree.
In animals with endolymphatic hydrops, lower concentrations of gentamicin were observed after 20 or 120 minutes of exposure and in both types of administration, when compared to controls. This difference reached statistical significance in the round window niche application group (Mann-Whitney, p = 0,007). A negative correlation between perilymphatic gentamicin concentration and hydrops degree could be observed in both groups, after 120 minutes of exposure (Spearman correlation, round window niche p<0,001; TT p = 0,005).
The study indicates that the endolymphatic hydrops degree has a negative interference on the delivery of gentamicin into the inner ear following middle ear application.
CITATION PLoS One. 2018 Nov 15;13(11):e0207467. doi: 10.1371/journal.pone.0207467