ACETAZOLAMIDE REDUCES THE ERYTHROPOIETIN RESPONSE TO HYPOXIA AT HIGH-ALTITUDE IN HUMANS

Objective: Acetazolamide, a carbonic anhydrase inhibitor, is often use d as a prophylactic drug for acute mountain sickness. It may interfere with erythropoietin production due to its action on ventilation and r enal function. Design: A randomized, double-blind, placebo-controlled trial with 2 x 250 mg acetazolamide daily beginning one day before asc ent from 590 m to 4559 m. Setting: High-altitude research facilities a t the Capanna Regina Margherita (Italy) at an altitude of 4559 m. Part icipants: Eighteen healthy volunteers, aged 24-42 years. Main outcome measure: Plasma erythropoietin was measured by radioimmunoassay before and after the ascent. Results: The increase of erythropoietin at high altitude was smaller in the acetazolamide group (increase by 10.8 +/- 7.8, U/L or 58%) than in the placebo group (increase by 22.7 +/- 13.8 U/L or 113%, p < .01). Conclusion: Acetazolamide reduces the erythrop oietin response to hypoxia in humans, which might also have therapeuti c implications in conditions such as secondary polycythemia.