Efficacy of Prophylactic Treatment of Oral Prochlorperazine for Acute Mountain Sickness

This was a prospective, single-blinded, field-based interventional trial involving consenting, healthy subjects aged >17 years. The study was conducted on the big Island of Hawaii, at sea level and at the summit of Mauna Kea volcano. Following randomization, subjects received either placebo or 10mg prochlorperazine, then immediately drove for 2 hours from sea level to the volcano summit (4205m). Participants spent 240 min at the summit, and they recorded their symptoms. AMS was defined by the previously validated Lake Louise Acute Mountain Sickness Score (LLAMS). Categorical variables were analyzed by chi-square; continuous variables analyzed by t-tests.

• Immediate descent from altitude. (Other): Immediate descent from altitude for severe symptoms or anyone who wished to discontinue their participation in the study.
• Diphenhydramine (Drug), also known as Benadryl: Diphenhydramine was available to counteract any potential extrapyramidal side effects of the study drug. The use of Diphenhydramine for this purpose is well established.
• Prochlorperazine 10 mg (Drug): Subjects in the Prochlorperazine arm were administered 10mg PO Prochlorperazine immediately prior to ascent

Primary outcomes

• Mean Lake Louise Acute Mountain Sickness Score (LLAMS) was utilized to compare symptoms of acute mountain sickness between the prochlorperazine and placebo groups [LLAMS Scores were recorded 360 minutes post study drug administration (which equals 120 minutes of driving time to the summit and an additional 240 minutes spent at the summit)]: The study drug was administered at sea level (time 0). Immediately thereafter, participants drove 120 minutes to the summit. They spent an additional 240 minutes at the summit. Symptoms were recorded 360 minutes after drug administration while still at the summit. The primary outcome was the difference in mean LLAMS scores between the prochlorperazine and placebo groups (t-tests). Previously validated Lake Louise Acute Mountain Sickness Score (LLAMS) were utilized. Categorical variables were analyzed by chi-square; continuous variables analyzed by t-tests.

Secondary outcomes

• Subjects meeting Lake Louise Acute Mountain Sickness Score (LLAMS) criteria for acute mountain sickness between the prochlorperazine and placebo groups [LLAMS Scores were recorded 360 minutes post study drug administration (which equals 120 minutes of driving time to the summit and an additional 240 minutes spent at the summit)]: The study drug was administered at sea level (time 0). Immediately thereafter, participants drove 120 minutes to the summit. They spent an additional 240 minutes at the summit. Symptoms were recorded 360 minutes after drug administration while still at the summit. Acute mountain sickness defined as having a headache score of at least one point, and a total score of at least three points. The prochlorperazine and placebo groups were compared for incidence of acute mountain sickness (chi-square)

Sex: All, ages: 18 Years to any, accepts healthy volunteers

Inclusion Criteria - Healthy subjects aged >17 years

Exclusion criteria-subject meets any of the following:

* Known allergy or contraindication to the study drug.
* Known or suspected pregnancy.
* Use of another analgesic or antiemetic within 8 hours of enrollment.
* History of chronic headaches.
* Inability to provide informed consent.
* Use of central nervous system depressants, including alcohol, opiates, and/or barbiturates, within 24 hours of the study start time.
* History of severe depression.
* History of dementia.
* Prior ascent and stay at 2500m for duration over 6 weeks within 30 days prior.

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• Peter Richman, MD, Principal investigator, CHRISTUS Health