Corticosteroid-LABA inhalers increase phonation threshold pressure (PTP) and flow (PTF) in rabbits

This study examined the effects of a combination corticosteroid plus long-acting beta₂ -adrenergic agonist inhaler (IC) on rabbit phonation.

White New Zealand male rabbits were assigned randomly to experimental and control groups (n = 11 per group). The experimental group received twice-daily doses of Advair HFA™ (fluticasone propionate 45 mcg and salmeterol 21 mcg) via a veterinary facemask with 1-way valve and spacer; the control group received aerosolized saline. After 8 weeks, animals were euthanized, larynges excised, frozen, and subsequently thawed and mounted on a standard bench apparatus. Phonation was elicited during 15 successive trials, and phonation threshold pressure (PTP; cmH₂ O) and flow (PTF; L/min) were quantified.

Repeated measures analysis of variance indicated significant differences between the experimental and control groups (p < 0.05). Mean PTP and PTF values were higher (worse) for rabbits that received Advair HFA™.

Following 8-week exposure to ICs, rabbit larynges required greater air pressure and flow to initiate phonation. Because even modest phonation onset differences can have a meaningful clinical impact on voice function, these findings suggest that LABA ICs may put patients at risk for voice disorders. Furthermore, these voice disorders may occur within a relatively short timeframe. The results from this study have important clinical implications for voice care in those who use ICs.

NA Laryngoscope, 133:2680-2686, 2023.