Prophylactic Low-Dose Acetazolamide and Acute Mountain Sickness

In the journal High Altitude Medicine & Biology, there appears a very interesting article entitled "Prophylactic low-dose acetazolamide reduces the incidence and severity of acute mountain sickness," authored by Martha C. Tissot van Patot and colleagues. This reports a study in which the investigators wished to evaluate prophylactic administration of low-dose acetazolamide for reducing the incidence and severity of acute mountain sickness (AMS) in the high risk (for AMS) setting of ascent from 1600 to 4300 meters (5249 to 14108 feet) in altitude.

Forty-four human subjects were enrolled in the study, in which there were treated for 3 days prior to ascent to 4300 meters and during 1 day at that altitude, either with acetazolamide 125 milligrams twice a day, or with placebo (capsules containing lactulose). Based upon questionnaire answers to determine the presence of AMS, it was determined that administration of acetazolamide (Diamox) reduced the incidence of AMS from 14% to 5%, both in incidence and severity.

This is a welcome finding, as being able to use a low dose of acetazolamide, which carries certain side effects such as paresthesia at higher doses, is a welcome addition to the pharmaceutical armamentarium of physicians and patients alike. Furthermore, the ascent studied was deemed to be "rapid," which is commonly the case. The study participants were driven from 1600 meters to 4300 meters in 2 hours. One issue remains is whether a full 3 days of acetazolamide are really necessary in order to "acclimatize" or pre-condition the climber. It may well be that it is sufficient to ingest the drug only for 24 hours (or some other period of time) prior to the ascent. The reason why 3 days were chosen as the pre-ascent treatment period is because this was done to accommodate another arm of the study, in which a 3-day treatment with Gingko biloba was necessary.

Preview the Annual Meeting of the Wilderness Medical Society, which will be held in Snowmass, Colorado July 24-29, 2009.

Join me from January 24 to February 2, 2010 for an exciting dive and wilderness medicine CME adventure aboard the Nautilus Explorer to Socorro Island, Mexico to benefit the Wilderness Medical Society.

photo by Brian Auerbach

Tags: acetazolamide, acute mountain sickness, high altitude illness, wilderness medicine, outdoor medicine, healthline