Microbubbles for Acoustically Mediated Drug Delivery to the Inner Ear

The blood-labyrinth barrier (BLB) is a selective endothelial barrier that maintains the homeostasis of the inner ear and protects it against toxic molecules and pathogens. This highly selective barrier represents a significant challenge for the delivery of therapeutic agents to the inner ear. To overcome this issue, various drug delivery methods have been developed. Among these modalities, microbubble-assisted ultrasound is an innovative and promising method for the noninvasive, targeted and efficient delivery of therapeutic agents through the round window membrane. The safety and the efficacy of this physical modality is strongly dependent on physiological properties of the targeted tissue, the pharmacological properties of the therapeutic molecules, the ultrasound parameters but also microbubble-related properties. The present review focuses on the current state of MB formulations and their use for the acoustically mediated inner ear drug delivery.