The possibility of anaesthesia by the inert gas argon in particular (even at 10 to 15 bar) suggests that the mechanism of action of volatile anaesthetics is an effect best described by physical chemistry , and not a chemical bonding action. However, the agent may bind to a receptor with a weak interaction . A physical interaction such as swelling of nerve cell membranes from gas solution in the lipid bilayer may be operative. Notably, the gases hydrogen, helium, and neon have not been found to have anaesthetic properties at any pressure. Helium at high pressures produces nervous irritation ("anti-anaesthesia"), suggesting that the anaesthetic mechanism(s) may be operated in reverse by this gas (., nerve membrane compression). Also, some halogenated ethers (such as flurothyl ) also possess this "anti-anaesthetic" effect, providing further evidence for this theory.
AB - The anti-asthmatic effect of theophylline may supplement those of inhaled steroids in asthma. The aim of the present trial was to study how the addition of theophylline compares to doubling the dose of inhaled steroid in asthmatics who remain symptomatic on beclomethasone dipropionate (BDP) 400 μg/day. The trial was designed as a randomized, double-blind, parallel-group study in several European countries. 69 patients were treated for 6 weeks with theophylline plus BDP 400 μg/day, compared to 64 patients treated with BDP 800 μg/day. The mean ± SD serum theophylline concentration was ± mg/l. Lung function measurements were made throughout the study and patients kept daily records of peak expiratory flow rate (PEF), symptoms and salbutamol usage. Forced expiratory volume in one second and PEF at week 6 were significantly increased by both treatments (p <). PEF variability was reduced by about 30% in both groups. There were significant improvements in asthma symptoms and rescue medication use (p <). There were no significant differences between the treatment groups. The study demonstrated clinical equivalence of theophylline plus beclomethasone dipropionate 400 μg/day and beclomethasone dipropionate 800 μg/day in patients whose asthma is not controlled on beclomethasone dipropionate 400 μg/d. The results support the use of theophylline as steroid-sparing agent. The combination of low-dose inhaled steroid plus theophylline is a suitable treatment for moderate asthma.