Acute mountain sickness (AMS) is one of three syndromes of altitude illness. It is very common when people venture over 2500 meters altitude. This illness is mainly induced by acute exposure to low partial pressure of oxygen at high altitude that will cause a pathological effect on humans. It presents a syndrome characterized by a collection of nonspecific symptoms, including headache and one of the following: gastrointestinal symptoms, fatigue and/or weakness, dizziness/light headedness or difficulty sleeping. Severity and incidence of these symptoms depend on the speed of ascent, altitude, duration of altitude exposure, physical exertion, and inherent genetic susceptibility.

T89 capsule is a modernized industrialized traditional Chinese herbal medicine. It is a botanical drug for oral use. The active substance is the water extract of Danshen (Radix Salivae Miltiorrhizae, RSM) and Sanqi (Radix Notoginseng, RN). T89 capsule also contains Bingpian (Borneol) which may promote absorption of the active substance. In recent years, several literatures and clinical studies have showed that oral administration of T89 may provide substantial benefits in the prevention or alleviation of symptoms associated with acute mountain sickness (AMS), including nausea, vomiting, headache, dizziness, fatigue, and sleep disturbance. Such effect was also observed in a pilot clinical study recently conducted in Tibet in China.

This study is a prospective, double-blind, randomized, placebo-controlled phase 2 clinical trial having three arms including T89 low-dose, T89 high-dose and a placebo controlled group. People will be screened against the inclusion/exclusion criteria after informed consent signed. Eligible subjects will be randomly assigned into one of three arms and instructed to use T89 orally twice daily for 14 days (Days 1-14) before ascending, and 5 days after ascending during the observation period (Days 15-19). Specifically, for subjects in the T89 high-dose group, they will take placebo instead of T89 from Day 1 to Day 12, and take T89 on Days 13-14. The primary efficacy parameter is Lake Louise Scoring System (LLSS) which will be evaluated by subject-self and principal investigator in clinic. Other efficacy parameters include Visual Analog Scales (VAS), exercise tolerance, blood lactate, and blood oxygen saturation that will be performed at altitude. The primary efficacy endpoint is the difference in LLSS total scores on Day 16 morning (12 hours after arrival at high altitude) compared between T89 and Placebo group. A total of 120 subjects will be enrolled with approximately 40 subjects in each arm, and a minimum of 100 subjects are expected to complete the study.