Ventilatory effects of aerosol gentamicin

Area of Science:

• Pulmonary Medicine
• Pharmacology
• Allergy and Immunology

Background:

• Bronchial provocation tests are used to assess airway hyperresponsiveness.
• Gentamicin is an antibiotic with potential respiratory effects.
• Asthma is characterized by airway inflammation and hyperresponsiveness.

Purpose of the Study:

• To investigate the effects of inhaled gentamicin and its vehicle on ventilatory function in subjects with and without respiratory conditions.
• To determine if inhaled gentamicin can induce obstructive reactions in asthmatic individuals.
• To explore the potential mechanisms, including irritant or immunological responses.

Main Methods:

• Bronchial provocation tests were conducted on 29 subjects (18 with asthma) using gentamicin solution (40 mg/ml) and vehicle solution via nebulizer.
• Ventilatory function, specifically forced expiratory volume in 1 second (FEV1) and vital capacity (VC), was measured before and after inhalations.
• Changes in FEV1 and VC were calculated as percentage variations from baseline to assess obstructive reactions.

Main Results:

• Seven subjects, all with asthma, exhibited an immediate FEV1 fall of 20% or more in response to either gentamicin or the vehicle solution.
• Reactions ranged up to 71% FEV1 fall, with a trend towards greater reactions to the vehicle solution.
• Pretreatment with salbutamol or sodium cromoglycate did not alter these reactions in two subjects. Skin prick tests for gentamicin were negative in all participants.

Conclusions:

• Inhaled gentamicin can induce significant obstructive reactions in a subset of asthmatic patients.
• The observed reactions appear to be non-immunological, likely stemming from an irritant effect of the drug vehicle.
• Further investigation into the irritant properties of drug formulations is warranted for inhaled medications.