Prospective, randomized cross-over trial to assess the ability of a dry-powder inhaler to reverse the local side effects of pressurized metered-dose inhalers.

OBJECTIVES: To determine whether a corticosteroid dry-powder inhaler could reverse the pharyngeal and laryngeal side effects produced by a corticosteroid pressurised metered-dose inhaler.

DESIGN: Prospective, randomized, controlled, cross-over, evaluator-blinded study.

SETTING: University Hospital Aintree, Liverpool, United Kingdom.

PATIENTS: Thirty-seven adults recruited over a 12-month period from Ear, Nose and Throat clinics at our University hospital. Patients were randomized into three groups using a computer-generated random number list and sealed opaque envelopes.

MAIN OUTCOME MEASURES: Scores were achieved on respiratory symptom and vocal performance questionnaires. Acoustic analysis was performed followed by a standardized biopsy of the posterior pharyngeal wall. Histological markers of inflammation were correlated with pharyngitis. The data were tested for normality using the Kalmogorov-Smirnov test. The Kruskal-Wallis analysis of variance was used to investigate differences between medians and ranges. The data were further investigated for correlations using the Spearman test. Discriminant analysis was used to examine the effect of the three groups on each variable.

RESULTS: Discomfort scores (median and range) were significantly lower after dry-powder inhaler use than with either a spacer or water gargle (p < 0.01). These worsened after restoring pressurized metered-dose inhaler therapy. The reduction in pharyngitis in each of the three groups was not significant. Vocal performance scores improved with dry-powder inhaler use. Jitter, shimmer, and closed-phase quotient scores improved with dry-powder inhaler use (p < 0.01). Shimmer scores deteriorated once the pressurized metered-dose inhaler was restored (p < 0.01). There was no significant difference between the groups in most observed parameters of inflammation (p > 0.01).

CONCLUSION: A dry-powder inhaler may alleviate the local side effects produced by a pressurized metered-dose inhaler. Laryngeal dysfunction appears to be particularly responsive to the absence of propellant. More observational and randomized controlled trials are necessary to examine existing inhalers and specifically, how and why they cause local side effects.