Thorax 1986;41:74-75 Effects of pholcodine and salbutamol on citric acid induced cough in normal subjects

Cough may be the presenting feature ofasthma in adults and children.12 Treatments for asthma, such as f stimulant drugs, are known to be effective in controlling the symptom.1 Ellul-Micaleff demonstrated the efficacy of oral terbutaline sulphate in a double blind, placebo controlled crossover study of 30 patients with chronic "allergic" cough.3 In whooping cough. inhaled salbutamol has been found to reduce the frequency and intensity of the whoop but not the cough.4 In contrast, Pavesio and Ponzone found a reduction in cough as well as whoop with oral salbutamol.5 The effectiveness of antitussive agents has been assessed most often by their action on cough induced by agents such as citric acid rather than spontaneous cough. Many techniques have been used to assess these effects.6 We have used the technique of establishing the threshold for citric acid induced coughs7 to compare the actions of placebo, oral salbutamol, oral pholcodine, and their combination in nine non-asthmatic subjects. Pholcodine has been shown to raise the threshold of coughing in response to citric acid inhalation8 and was included in this study as a positive control.