xRead - Olfactory Disorders (September 2023)

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PATEL et al.

TABLE IX-38 Use of intranasal insulin to treat OD Study Year LOE Study design

Study groups 38 patients with

Clinical end point Conclusions

Very slightly

Butanol threshold test (0–7) Serum insulin and glucose levels

Rezaeian et al 1599

2018

2

RCT

improved olfactory threshold ( + 1.11 vs –0.02) No change in serum insulin or glucose levels in either group

undifferentiated hyposmia for > 6months (36 completed evaluation) Gelfoam with 40 IU insulin (n = 18) Saline-soaked gelfoam(n = 18) Ten patients with PIOD Single dose of 40 IU intranasal insulin (n = 10) Saline 1 year later (n = 7) placed in OC twice weekly for 4 weeks

Schöpf

2015

3

Prospective pilot

SS-TDI Olfactory intensity Hedonic rating

No significant change in TDI score or each individual domain Threshold score minimally improved in 6 patients ( + 1) Increased intensity score after insulin No change in hedonic rating Strong correlation with BMI and improved olfactory scores with insulin

et al 1600

BMI = body mass index; LOE = level of evidence; OC = olfactory cleft; OD = olfactory dysfunction; PIOD = postinfectious olfactory dysfunction; RCT = random ized controlled trial; SS-TDI = Sniffin’ Sticks threshold, discrimination, identification combination; TDI = threshold, discrimination, and identification.

Use of theophylline or other PDEIs to treat OD Aggregate grade of evidence for systemic PDEIs : C (Level 2: two studies; Level 3: one study; Level 4: six stud ies). Aggregate grade of evidence for intranasal theo phylline : D (Level 4: two studies). Benefit : Inconclusive evidence that OF improves with oral or topical administration of PDEIs. Lack of consider ation for spontaneous improvements, control populations, and validated assessment tools limit the interpretability of results. Harm : Described adverse events include restlessness, tachycardia, nausea, anorexia, GI discomfort, and sleep disturbance. These may be less significant with topical administration. Cost : Low, as the oral PDEIs are available in generic form and FDA approved in other conditions (eg, asthma, bronchitis, emphysema, erectile dysfunction, and insom nia). Intranasal theophylline is not commercially available as an FDA-approved medication. Benefits-harm assessment : The potential for harm from oral PDEIs outweighs the potential benefit. There is

not enough evidence to assess benefit versus harm for top ical theophylline. Value judgments : The evidence for the use of oral PDEIs in OD is inconclusive and there exists potential for harm. The evidence for topical theophylline is inconclu sive and warrants further investigation. Policy level : Recommendation against oral PDEIs for use in treating OD. No recommendation can be currently made regarding use of intranasal theophylline to treat OD. Intervention : Oral PDEIs should not be recommended in patients with OD as the potential for benefit is inconclu sive and there exists potential for harm. Providers should inform their patients that the evidence for intranasal theo phylline is preliminary and inconclusive before consider ing its use. 7 Intranasal insulin Insulin receptors are found throughout the human body, including the CNS. In the brain, insulin receptors have been noted to be present within the OB, and the