A randomised controlled trial of sodium citrate spray for non‐conductive olfactory disorders

Abstract

Objectives Previous research has suggested that sodium citrate improves hyposmia by decreasing mucus calcium levels in the nose. This study aimed to confirm or refute this effect in a single application and assess potential side‐effects. Design Study design was a randomised double‐blind controlled trial of sodium citrate nasal spray (intervention) vs sterile water (control). Fifty‐five patients with non‐conductive olfactory loss were randomised to receive the intervention or placebo. Setting Tertiary care clinic. Main outcome measures The primary outcome measure was improvement in measured olfactory thresholds for phenyl ethyl alcohol (PEA) over 2 hours. Other outcome measures assessed were improvement in olfactory thresholds in 1‐butanol, eucalyptol and acetic acid; number of responders with a clinically relevant response in each arm; and adverse effects. Results A significant effect was seen in the intervention arm for PEA and for 1‐butanol and eucalyptol when compared to the control arm (P<.05); 32% of the intervention arm responded in terms of improved sensitivity towards some of the odours. Minor adverse effects noted included sore throat, nasal paraesthesia, slight rhinorrhoea and itching. The duration of effect of the citrate is transient, peaking at 30‐60 minutes after application. Conclusions Sodium citrate yields some potential as a treatment for non‐conductive olfactory loss; however, these findings require corroboration in further clinical trials looking at longer term regular use of the spray as a viable therapeutic option for patients where it would be applied at frequent intervals such as before mealtimes.

What to propose to treat post-viral non-conductive smell disorder in COVID-19? - systematic review with meta-analysis

“…After the reading, six articles were excluded because their samples were composed of patients with obstructive nasal disease (table 1). However, of the 13 studies included in the qualitative analysis (table 2), ve studies were unique in their treatment [10,[21][22][23][24] and four did not have enough data for quantitative analysis (meta-analysis) [25][26][27][28]. Thus, four studies were selected for the meta-analysis involving 336 patients [29][30][31][32] (table 3).…”

“…Outcome measures were determined by symptom scores and objective methods of olfactory testingwith the Sni n`Sticks test as the most common test used in the studies. Ten studies compared the mean TDI score ("T" -threshold, "D"discrimination, "I" -identi cation) before and after drug treatment in NCSD (total of six drugs) [10,[21][22][23][24][25][26][27][28], while four compared the mean TDI score before and after olfactory training in NCSD [29][30][31][32] (table 3). Of the studies with drug treatment, ve were the only ones for the drug they proposed to analyze (oral caroverine, oral vitamin A, intranasal insulin, intravenous pentoxifylline and oral lipoic acid) [10,21-24] and four were on intranasal sodium citrate [26][27][28]; however, studies with sodium citrate did not provide su cient pre-and posttreatment data for meta-analysis.…”

“…Of the 13 included articles, three studies speci ed the blinding methods of participants and professionals, as well as the blinding of outcome assessors providing enough information to allow judgment [22,24,27].…”

“…In a randomized, double-blind clinical trial with 55 patients with NCSD (post-viral, post-traumatic or idiopathic), 31 participants received intranasal sodium citrate (3.5g/140ml), and 24 received 0.9% sodium chloride [27]. The olfactory thresholds were assessed through a test using phenylethyl alcohol (roses), 1-butanol (pear), acetic acid (vinegar) and eucalyptol (menthol), previously validated by the same authors.…”

Treatment of post‐viral olfactory dysfunction: an evidence‐based review with recommendations

“…In regard to nonsteroidal topical therapies (Table 7), 3 studies investigated intranasal sodium citrate. [32][33][34] Philpott et al conducted a double-blinded, randomized, placebo-controlled trial of 55 patients with nonconductive OD, the majority of which had PVOD (42%) or idiopathic loss (26%). 32 Though subgroup analyses for patients with PVOD was not completed, there was a significant a Higher number of asterisks indicate higher quality study.…”