Topical Glutamate Diacetate: A Promising Therapy for Post-Coronavirus Disease 2019 Olfactory Dysfunction Through Calcium Modulation

Abstract

Background

Olfactory dysfunction is a frequent symptom experienced by individuals recovering from coronavirus disease 2019 (COVID-19) and significantly impacts daily life activities. Recent studies suggest that reducing nasal calcium levels may help restore olfactory function. Glutamate diacetate (GLD) is a natural sequestering agent that binds calcium ions and may offer therapeutic benefits in managing post-COVID olfactory dysfunction.

Objective

This study aimed to evaluate the effectiveness of topical GLD treatment in reducing nasal calcium levels and improving olfactory function in individuals with chronic olfactory dysfunction following COVID-19.

Methods

A double-blind, placebo-controlled trial was conducted with 66 participants who were randomized into two groups: GLD (1% solution) and saline placebo (0.9% solution). Participants received nasal treatment three times daily for six months. Olfactory function was assessed using the Sniffin’ Sticks test, measuring threshold (T), discrimination (D), and identification (I) scores. Nasal calcium levels were also measured. Statistical analysis included independent t-tests and change-from-baseline comparisons.

Results

Significant improvements were observed in the GLD group across olfactory assessments. By month 6, threshold scores increased by 0.78 ± 0.15, discrimination scores by 0.72 ± 0.15, and identification scores by 1.80 ± 0.15, all exceeding gains in the saline group. Nasal calcium levels decreased significantly in the GLD group (7.36 ± 1.21 mM vs 2.49 ± 0.51 mM in saline), suggesting a contribution mechanism in olfactory improvement.

Conclusion

GLD treatment resulted in statistically significant improvements in olfactory function and a reduction in nasal calcium levels in individuals with post-COVID olfactory dysfunction. However, the observed changes did not reach the threshold for clinical significance. These findings suggest a potential role for GLD in olfactory recovery, but further studies are needed to evaluate its long-term efficacy and clinical relevance.

Keywords

coronavirus disease 2019 calcium sequestering agent olfactory dysfunction glutamate diacetate controlled trial Sniffin’ sticks threshold discrimination identification

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