Uptake of gadolinium and dexamethasone in rat inner ear and facial nerve using different administrations.

Abstract

Background: The pathway by which drugs are injected subcutaneously behind the ear to act on the inner ear has not been fully elucidated.

Objectives: To compare the uptake of gadopentetate dimeglumine (Gd-DTPA) and dexamethasone (Dex) in the cochlea and facial nerve of rats following different administrations.

Materials and methods: Magnetic resonance imaging was applied to observe the distribution of Gd-DTPA in the facial nerve and inner ear. We observed the uptake of Dex after it was injected with different methods.

Results: Images of the intravenous (IV) and intramuscular (IM) groups showed that the bilateral cochlea of the rat was visualized almost simultaneously. While in the left post-auricular (PA) injection group, it was asynchronous. The maximum accumulation (C_max) of the Gd in the left facial nerve of the PA group (35.406 ± 5.32) was substantially higher than that of the IV group (16.765 ± 3.7542) (p < .01).

Conclusions: Compared with systemic administration, PA has the advantages of long Gd and Dex action time and high accumulation concentration to treat facial nerve diseases.

Significance: The distribution of Gd and Dex in the inner ear and facial nerve of rats following PA injection might be unique.