Povidone-iodine nasal spray (Nasodine) for the common cold: a randomized, controlled, double-blind, Phase III clinical trial.

AIM

To determine the safety and efficacy of a 0.5% povidone-iodine nasal spray (Nasodine) as a treatment for the common cold (ACTRN12619000764134).

METHODS

A multi-center, randomized, controlled, double-blind Phase III study was conducted to assess the impact of Nasodine on the common cold. Two hundred and sixty (260) euthyroid adults with qualifying cold symptoms and meeting inclusion/exclusion criteria were randomized 2:1 to Nasodine or matching saline nasal spray (SNS), each applied 4 times daily for 5 days. Cold severity was reported using the WURSS-21 survey. The primary endpoint was impact on nasal symptoms (4-item scale), with the validated 19-item Global Severity Score (GSS) as the key secondary endpoint.

RESULTS

All cold severity outcomes pointed in favor of Nasodine over SNS. In the ITT ( = 260), the Nasodine benefit over SNS on nasal symptoms was 8.4% ( = 0.217). For GSS, the benefit was 12.6% ( = 0.054) in the ITT population. subset analyses showed markedly improved benefits of Nasodine: In subjects with stronger symptoms at enrollment (ES), the GSS benefit was 17.1% ( = 0.023); for those with confirmed viral infection (VES), GSS benefit was 23.0% ( = 0.048); and for those enrolled within 24 h of symptom onset (24S), GSS benefit was 39.7% ( = 0.024). In terms of functional impairment, the Nasodine benefit was greater in all subsets, with 16.1% ( = 0.041) benefit in ITT, 22.2% in ES ( = 0.012), 32.1% in VES ( = 0.023) and 37.1% in 24S ( = 0.093). Nasodine was well tolerated, with mild transient nasopharyngeal discomfort being a common adverse effect.

CONCLUSION

Nasodine treatment had a consistently positive and clinically meaningful benefit on overall cold severity when compared with saline nasal spray. Early treatment after symptom onset is an important efficacy factor.

CLINICAL TRIAL REGISTRATION

https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=377353&isReview=true, identifier ACTRN12619000764134.