RESUMO
BACKGROUND: COVID-19 has been associated with olfactory disturbances in many infected patients. The increase in calcium levels in nasal secretions plays an essential role in the olfactory process with a desensitizing effect on olfactory receptor neurons and negative effects on odor transmission. Calcium chelating agents have the ability to bind calcium in nasal mucus and prevent the negative effects associated with calcium increase. OBJECTIVES: The aim of this work is to demonstrate the intra-nasal topical application of sodium phytate, an environmentally friendly, non-harmful calcium chelating agent, to reduce the adverse effects of calcium on olfactory function and improve olfactory dysfunction according to COVID-19. METHODS: Fifty-two patients with a previous COVID-19 and olfactory dysfunction lasting longer than 90 days were enrolled in a prospective, randomized, blinded, controlled clinical trial. Patients were divided into two equal groups: 26 patients received nasal spray containing 0.9% sodium chloride and 26 patients received nasal spray containing 1% sodium phytate. Olfactory function was measured before treatment and 1 month later using the Sniffin' Sticks test. Calcium content of nasal secretions was determined before and after treatment with an ion-selective electrode. RESULTS: A significant improvement from anosmia to hyposmia was demonstrated after the use of sodium phytate compared with no improvement after the use of sodium chloride. In addition, a decrease in the level of calcium in nasal secretions was observed after the use of sodium phytate. CONCLUSION: Sodium phytate has benefit role on improving the olfactory function after COVID-19.