A review of frequently used Kampo prescriptions: Part 2—Hangekobokuto

Abstract Background The origin of hangekobokuto (HKT) is from Jin Gui Yao Lue ( Kinkiyōryaku in Japanese), and it has been indicated for treating throat discomfort in women. Key Findings HKT consists of five crude drugs. Clinical studies have shown that HKT can improve the swallowing reflex by increasing the substance P level in saliva; improve the cough reflex; reduce pneumonia in patients with dementia, cerebrovascular disease, Alzheimer's disease, or Parkinson's disease; reduce postoperative aspiration pneumonia in patients who undergo cardiovascular surgery; and improve depression and anxiety scores in patients with globus hystericus. Furthermore, HKT has been reported to increase serotonin (5‐HT) and noradrenaline levels in the hypothalamus, and dopamine (DA) levels in the striatum in a healthy rodent model; improve 5‐HT levels in the striatum and hippocampus, and ameliorate 5‐HT and DA reductions in the whole brain in an acute stress model; improve 5‐HT levels in the striatum, and ameliorate 5‐HT and DA reductions in the prefrontal cortex in a chronic stress model; and decrease corticosterone and corticotropin‐releasing factor levels in a chronic stress model. Reported adverse events of HKT include interstitial pneumonia (0.38 per 100 000 cases) and liver damage (0.89 per 100 000 cases), which are rare. Conclusion HKT is widely used and shows a low rate of adverse events. Several clinical studies have reported its effects in reducing aspiration pneumonia and improving depression and anxiety, some of which may be explained by the regulation of monoamines and stress hormones in the brain and substance P levels in the oral cavity.