[Effects of oxatomide, H1-antagonist, on postinfectious chronic cough; a comparison of oxatomide combined with dextromethorphan versus dextromethorphan alone].

H1 antihistamines have been shown to have antitussive effects in patients with asthma and postnasal drip. In Japan, no study has been performed to determine whether orally administered oxatomide, H1 antihistamine, can reduce the chronic cough seen in patients with post-upper-airway infection (postinfection). Patients who had chronic cough of more than three weeks' duration and a history of post-upper-airway infection took part in the study. None had any history of nasal disease, gastroesophageal reflux, bronchial asthma, or other chronic pulmonary disease. All patients were non-smokers, and none used ACE inhibitors. They had normal CRP concentrations, peripheral white blood cell and eosinophil counts, serum IgE concentrations, titers of cold agglutinins and antibodies to Mycoplasma pneumoniae, chest roentgenograms, and respiratory function tests. A prospective randomized, open design was used. The effect of one week of treatment with dextromethorphan (D) or with D plus oxatomide (D + O) on the severity of cough, as estimated by cough diary, were examined. Twenty-two patients entered the study, and 20 were eligible for efficacy and side-effect analyses. Nine patients receiving D and 11 receiving D + O completed the protocol. Patients' characteristics before the start of the study, such as severity and duration of cough, and laboratory data, were not significantly different between the two groups. From trial day 5 to 7, improved rates of cough were significantly higher with D + O than with D alone (p < 0.05). Combination therapy with oxatomide and dextromethorphan reduces subjective perception of cough as estimated by cough diary. These results suggest that oxatomide, H1 antihistamine may improve chronic cough in patients with post-upper-airway infection.