Investigational drugs for the treatment of olfactory dysfunction

Olfactory dysfunction could be the sign of acquired or degenerative diseases. The loss of the sense can be caused by a damage in the nasal structure (olfactory epithelium) or a neuro inflammation/degen- eration in the superior olfactory pathway. The understanding of the origin of the smell alteration would be desirable for appropriate management of the problem. Unfortunately, clinical investigations do not always allow to define the exact cause. This review discusses the treatments available and their mechanism of action based on the administration methods; in fact, just looking at the results obtained by the researcher using topic versus systemic treatment, might be possible to speculate about the peripheral or central origin of the olfactory disorder. Because COVID-19 causes olfactory loss and several treatments (topical and systemic) have been tested in this disease, we have decided to use this model of acquired olfactory loss to discuss the different therapeutical option. The authors believe these treatments might be an option also for treating olfactory disease related to neurodegeneration.