Vitamin A containing intranasal drops improve odour detection threshold

Area of Science:

• Otolaryngology
• Neuroscience
• Pharmacology

Background:

• Retinoic acid (Vitamin A metabolite) supports olfactory neuron regeneration in animal models.
• Clinical evidence suggests potential therapeutic benefits for olfactory dysfunction (OD).
• Intranasal Vitamin A's efficacy in non-sinonasal OD remains largely uninvestigated.

Purpose of the Study:

• To investigate the efficacy of intranasal Vitamin A (Coldastop) combined with olfactory training (OT) for treating non-sinonasal OD.
• To compare intranasal Vitamin A with olfactory training alone and intranasal steroids plus olfactory training.

Main Methods:

• A prospective, non-blinded comparative study involving 144 patients with post-infectious, post-traumatic, or idiopathic OD.
• Treatment groups included OT alone, OT + intranasal Vitamin A (OT+VA), and OT + intranasal steroids (OT+S) for 12 weeks.
• Olfactory function was assessed pre- and post-treatment using the "Sniffin' Sticks" test (odor threshold, discrimination, identification, TDI scores).

Main Results:

• All treatment regimens showed statistically significant improvements in olfactory subtest and composite scores.
• The OT+VA group demonstrated the most significant improvement in odor threshold (F(2, 139)=3.2, P=0.044).
• A higher proportion of patients in the OT+VA group achieved clinically significant improvements across all tested olfactory measures.

Conclusions:

• Intranasal Vitamin A, when combined with olfactory training, shows promise in treating olfactory dysfunction.
• Further large-scale randomized trials are warranted to confirm these findings.
• Intranasal Vitamin A may offer a beneficial therapeutic option for patients with smell loss.