Spanish researchers have shown that asthma inhalers can give readings in breath alcohol tests that are, in most cases, above the legal limit fixed by Spanish traffic police.
Most worrying is the fact that aerosols without ethanol as the vehicle produced false positive results, says University of Cádiz pharmacologist Juan Manuel Ignacio-García, lead author of the report (Medicina Clinica 2002;118:332-4).
The study was on 60 volunteers with asthma attending the Hospital Comarcal de Ronda in Cádiz. Ten minutes before the participants were given an inhaler to use, they underwent a breath test on the Alcotest 7110-E device, an infrared breath alcohol analyser manufactured by Dräger, based in Lübeck, Germany, and widely used in Spain and France. The researchers then studied the effects on further test readings of different inhalers containing salbutamol, salmeterol, formoterol, budesonide, and fluticasone, administered as two puffs, in homogeneous groups of five patients.
Readings were taken at 1, 2, 3, 5, and 10 minutes after puffing. At baseline all readings were negative, but all the inhalers resulted in positive readings in the first few minutes after administration, the values decreasing rapidly and linearly to zero at 10 minutes.
The mean readings for salbutamol, salmeterol, and budesonide were 0.45, 0.44, and 0.32 mg of alcohol per litre of air, respectively, at one minute. At three minutes these values were 0.08, 0.09, and 0.07 mg/l. In France and Spain the maximum permitted level of alcohol is 0.25 mg/l. In Britain it is 0.35 mg/l.
The researchers then compared the effects of inhalers with and without alcohol as a vehicle in two groups of five patients. Each group was administered two puffs of either Butoasma (salbutamol with ethanol) or Ventolin (salbutamol without ethanol). No significant differences between the groups were found at baseline.
At one minute, the mean readings on the breath test were 0.45 mg/l (SD 0.17) in the patients who were given Butoasma and 0.35 (0.21) in patients given Ventolin.
Dr Ignacio-García says the only confounding factor that could have led to the false positive result in the study was the propellant gases used in the aerosols, in particular chlorofluorocarbons. He says the next challenge is to find out what happens with puffer devices that don't use propellants—for example, dry powder inhalers (Accuhaler, Diskhaler, and Turbohaler).
A spokeswoman for London's Metropolitan Police, who use a different breath test device, said they always wait 20 minutes before taking a breath test if it is known that someone has just used an inhaler.
