Post-COVID-19 Anosmia and Therapies: Stay Tuned for New Drugs to Sniff Out

Abstract

Background: Anosmia is defined as the complete absence of olfactory function, which can be caused by a variety of causes, with upper respiratory tract infections being among the most frequent causes. Anosmia due to SARS-CoV-2 infection has attracted attention given its main role in symptomatology and the social impact of the pandemic. Methods: We conducted systematic research in a clinicaltrials.gov database to evaluate all active clinical trials worldwide regarding drug therapies in adult patients for anosmia following SARS-CoV-2 infection with the intention of identifying the nearby prospects to treat Anosmia. We use the following search terms: “Anosmia” AND “COVID-19” OR “SARS-CoV-2” OR “2019 novel coronavirus”. Results: We found 18 active clinical trials that met our criteria: one phase 1, one phase 1–2, five phases 2, two phases 2–3, three phases 3, and six phases 4 studies were identified. The drug therapies that appear more effective and promising are PEA-LUT and Cerebrolysin. The other interesting drugs are 13-cis-retinoic acid plus aerosolized Vitamin D, dexamethasone, and corticosteroid nasal irrigation. Conclusions: COVID-19 has allowed us to highlight how much anosmia is an important and debilitating symptom for patients and, above all, to direct research to find a therapy aimed at curing the symptom, whether it derives from SARS-CoV-2 infection or other infections of the upper airways. Some of these therapies are very promising and are almost at the end of experimentation. They also provide hope in this field, which not addressed until recently.

Proteoform Analysis of the Human Olfactory System: A Window into Neurodegenerative Diseases

“…Due to the complexity of the human brain, the characterization of proteome profiles within specific areas, brain structures, and biofluids, is essential to understanding the biochemical basis of structural specialization and alterations associated with diseases involving the sense of smell [ 12 ].…”

“…Moreover, one of the most frequent causes of loss of smell is the infectious damage caused by the SARS-CoV-2 viral agent, the etiological cause of COVID-19 disease. A growing number of evidence shows that olfactory damage (OD) may be caused by both mechanical damage, such as the inflammatory obstruction of the roof of the nasal cavity at the cribriform plate, and by structural damage, such as the neuronal insults on the different level of olfactory system, according to cellular mechanisms not clarified [ 11 , 12 ]. During the first COVID-19 outbreak, when it was considered a pandemic, OD was one of the main symptoms frequently described by patients [ 13 , 14 ].…”

Neurofilament Expression as a Biomarker of Post-COVID-19 Sudden Sensorineural Hearing Loss

“…Another important issue in explaining this observation could be the evaluation of potential vestibular pathway impairment through vestibular-evoked myogenic potentials (VEMPs) in patients with the recurrent presence of vertigo [ 43 ]. This case report demonstrates a temporal association between COVID-19 infection, sudden sensorineural hearing loss, and increased neurofilament expression in post-COVID-19 conditions [ 44 ], suggesting ideas for investigations useful for the prognosis of SSHL and supporting potential therapy [ 1 ]. This association should be carefully evaluated and not be dismissed as a coincidental event.…”

“…COVID-19 is a severe acute respiratory syndrome induced by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), which has rapidly become one of the greatest challenges of our century, causing great medical and socioeconomic upheaval [ 1 , 2 ]. The pandemic was a global health concern that required a rapid biomedical response to limit the spread of the disease and deaths.…”

Platelet-Rich Plasma (PRP) in the Treatment of Long COVID Olfactory Disorders: A Comprehensive Review

“…Timing is another critical aspect. Initiating PRP treatment too early or too late during olfactory dysfunction could influence its effectiveness [61,62]. Similarly, the duration of treatment needs to be carefully calibrated; too short a course may be insufficient for recovery, while too long a course could lead to diminishing returns [63].…”