Intra-nasal Disodium Orthophosphate Is Beneficial in Improving Olfactory Dysfunction Post COVID-19

Abstract

Objectives:

An association between COVID-19 and olfactory dysfunction has been reported worldwide. It has been recognized that olfactory dysfunction may be the only sign of COVID-19. Reports demonstrate an increase of the nasal calcium levels in the patients with olfactory dysfunction. Disodium orthophosphate is a calcium chelating agent which may be associated with improving olfactory function. The main objective of this study is to investigate the effect of intranasal disodium orthophosphate on reducing the increase of calcium in the mucus of patients with olfactory dysfunction post COVID-19, thereby improving the olfaction process.

Methods:

Fifty-two patients with a history of COVID-19 and olfactory dysfunction persisted more than 6 months were enrolled in prospective randomized blinded double controlled clinical trial. They received a nasal spray containing either 0.9% sodium chloride or 1% disodium orthophosphate. Olfactory function was assessed before treatment and 2 months later using the Sniffin’ Sticks test. Quantitative analysis of calcium level in the nasal secretions was performed using a prepared screen-printed ion-selective electrode.

Results:

Compared to sodium chloride, intranasal disodium orthophosphate resulted in a reduction in nasal calcium concentrations. Clinically, 81% of patients in this group demonstrated improvement in olfactory function, with a shift from anosmia to hyposmia based on TDI score classification.

Conclusions:

Intra-nasal disodium orthophosphate is beneficial in improving olfactory dysfunction post COVID-19.