Intranasal sodium citrate in quantitative and qualitative olfactory dysfunction: results from a prospective, controlled trial of prolonged use in 60 patients

Objectives We have previously shown that treatment with intranasal sodium citrate may be beneficial in post-infectious olfactory dysfunction. Sodium citrate reduces free intranasal calcium and is, therefore, thought to prevent calcium-mediated feedback inhibition at the level of the olfactory receptor. We aimed to determine whether treatment with a 2-week course of intranasal sodium citrate improves quantitative olfactory function in patients with post-infectious impairment. We also aimed to determine whether sodium citrate is beneficial in treating qualitative olfactory dysfunction. Methods We performed a prospective, controlled study. Patients applied intranasal sodium citrate solution to the right nasal cavity for 2 weeks. The left nasal cavity was untreated and, therefore, acted as an internal control. Monorhinal olfactory function was assessed using the Sniffin' Sticks composite 'TDI' score, before and after treatment. The presence of parosmia and phantosmia was also assessed. Results Overall, there was a significant increase in TDI after treatment (using the best of right and left sides). Treatment with sodium citrate did not significantly improve quantitative olfactory function, compared to control. The proportion of patients reporting parosmia did not change significantly after treatment. However, there was a significant reduction in the proportion of patients reporting phantosmia, at the end of the study period. Conclusions Treatment with intranasal sodium citrate for a period of 2 weeks does not appear to improve quantitative olfactory function in patients with post-infectious impairment, compared to control. It may, however, be beneficial in treating phantosmia, which should be further addressed in future work.

Automated summary

This study investigated the effect of intranasal sodium citrate treatment on patients with post-infectious olfactory dysfunction. The results showed that sodium citrate did not significantly improve quantitative olfactory function but was effective in reducing phantosmia. Further research is needed to explore the potential benefits of sodium citrate in treating qualitative olfactory dysfunction.