A traditional chinese herbal medicine, banxia houpo tang, improves cough reflex of patients with aspiration pneumonia

To the Editor: Absence or attenuation of the cough1 and swallowing2 reflex is shown in older patients with aspiration pneumonia. We investigated the effects of a traditional Chinese medicine, banxia houpo tang (BHT, Hange Koboku-To in Japanese, formula magnolia et pinelliae), on the cough reflex in older stroke patients. Sixteen patients, mean age 78, who had at least one episode of aspiration pneumonia and various degrees of cerebral atrophy and lacunar infarctions were randomly divided into two groups. One group (male:female (M:F) = 5:2, mean age ± standard deviation 79.6 ± 4.3) was given BHT extracts, and another group (M:F = 7:2, mean age 70.5 ± 5.6) took placebo. Daily BHT extracts of 4.5 g were divided into three doses of 1.5 g each and wrapped in white paper and were taken orally 30 min before each meal, three times a day for 4 weeks. Other drugs such as calcium antagonists for hypertension and nitrates for angina pectoris were taken without limitations. Some patients took sedatives, antitussives, or antipsychotic drugs. Patients who took angiotensin-converting enzyme inhibitors for hypertension were excluded from the study. A placebo (1.5 g lactose each time) was given in the same way as BHT. BHT and placebo were distributed to patients by a controller, and other hospital employees (doctors, nurses, and other caregivers) were prohibited from asking patients which kind of agents they were taking. The cough reflexes of eight healthy volunteers (M:F = 5:3, mean age 80 ± 3) who led an active daily life were also examined as normal controls. The cough reflex was examined as reported previously.3 Briefly, subjects inhaled nebulized citric acid solution delivered by an ultrasonic nebulizer. The citric acid was dissolved in the saline solution, providing incremental concentrations from 0.3 to 360 mg/mL. Subjects' coughs were recorded using a tape recorder. The cough threshold was defined as the concentration at which subjects coughed at least five times, provided they also coughed at subsequent higher concentrations. In the BHT group, the threshold concentration of citric acid for coughing significantly decreased from 59.5 ± 22.3 mg/mL before administration to 15.7 ± 3.4 mg/mL after administration (P < .01). Three patients improved their status in taking meals. In the control group, the values remained the same (47.5 ± 25.1, P> 0.5). In the healthy volunteers, the result was 6.3 ± 1.3 mg/mL (Figure 1). In the banxia houpo tang (BHT) group, the mean threshold concentration ± standard deviation of citric acid for coughing significantly decreased from 59.5 ± 22.3 mg/mL before administration to 15.7 ± 3.4 mg/mL after administration (P < .01). Three patients improved their status in taking meals. In the control group, the values remained the same (47.5 ± 25.1, P> .5). In the healthy volunteers, the result was 6.3 ± 1.3 mg/mL. These data suggest that BHT improves the impaired cough reflex. We have already reported that BHT improved the swallowing reflex of stroke patients, and substance-P in their saliva increased with this agent.4 In addition, we have reported that BHT improved the swallowing reflex of patients with Parkinson's disease.5 All these findings suggest that BHT could prevent aspiration pneumonia in older people. It may be because BHT allows substance-P to increase, but the detailed mechanism is still unknown. BHT has a long history of use in patients with swallowing disorders,6 and the methodology and its safety have been clinically established. Further studies of its effects and mechanisms will be needed.