Reducing the incidence of high-altitude pulmonary edema.

TO THE EDITOR: In their randomized trial, Maggiorini and colleagues (1) report their impressive outcome that both tadalafil and dexamethasone may reduce the incidence of high-altitude pulmonary edema. They used a dosage of 10 mg twice daily for tadalafil or 8 mg twice daily for dexamethasone from the morning of the day before ascent until the end of the study. We are concerned about the dose adjustments of both drugs for the trial. A previous study used the phosphodiesterase-5 inhibitor sildenafil at a dosage of 40 mg 3 times daily at 6 to 8 hours after arrival at high altitude that was maintained for 6 days to inhibit altitude-induced hypoxemia and pulmonary hypertension (2). Similarly, another study used a sildenafil dosage of 25 mg or 100 mg every 8 hours for 12 weeks to treat high-altitude pulmonary arterial hypertension (3). Both studies found the treatments to be effective. In the case of dexamethasone, an initial dose of 8 mg, followed by 4 mg every 6 hours, has been used to treat highaltitude cerebral edema (4). Could the authors explain how they chose the drug regimen for their prophylaxis trial?