Effects of selective and nonselective beta-blockade on 24-h ambulatory blood pressure under hypobaric hypoxia at altitude.
BACKGROUND
Little is known about the effects of cardiovascular drugs at high altitude.


OBJECTIVE
To assess 24-h blood pressure (BP) and heart rate (HR) during short-term altitude exposure in healthy normotensive persons treated with carvedilol or nebivolol.


METHODS
Participants were randomized in double-blind to placebo, nebivolol 5 mg once daily or carvedilol 25 mg b.i.d. Tests were performed at sea level (baseline and after 2 weeks treatment) and on second to third day at altitude (Monte Rosa, 4559 m), still on treatment. Data collection included conventional BP, 24-h ambulatory BP monitoring (ABPM), oxygen saturation (SpO2), Lake Louise Score and adverse symptoms score.


RESULTS
Twenty-four participants had complete data (36.4 ± 12.8 years, 14 men). Both beta-blockers reduced 24-h BP at sea level. At altitude 24-h BP increased in all groups, mainly due to increased night-time BP. Twenty-four-hour SBP at altitude was lower with carvedilol (116.4 ± 2.1 mmHg) than with placebo (125.8 ± 2.2 mmHg; P < 0.05) and intermediate with nebivolol (120.7 ± 2.1 mmHg; NS vs. others). Rate of nondipping increased at altitude and was lower with nebivolol than with placebo (33 vs. 71%; P = 0.065). Side effects score was higher with carvedilol than with placebo (P = 0.04), and intermediate with nebivolol. SpO2 at altitude was higher with placebo (86.1 ± 1.2%) than with nebivolol (81.7 ± 1.1%; P = 0.07) or carvedilol (81.1 ± 1.1%; P = 0.04).


CONCLUSIONS
Both carvedilol and nebivolol partly counteract the increase in BP at altitude in healthy normotensive individuals but are associated with a lower SpO2. Carvedilol seems more potent in this regard, whereas nebivolol more effectively prevents the shift to a nondipping BP profile and is better tolerated.
Department of Cardiology, S Luca Hospital, IRCCS, Istituto Auxologico Italiano, Milan, Italy.
Grzegorz
G
Bilo
Gianluca
G
Caldara
Katarzyna
K
Styczkiewicz
Miriam
M
Revera
Carolina
C
Lombardi
Alessia
A
Giglio
Antonella
A
Zambon
Giovanni
G
Corrao
Andrea
A
Faini
Mariaconsuelo
M
Valentini
Giuseppe
G
Mancia
Gianfranco
G
Parati
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000188:drug therapy / Q000503:physiopathology; D001578:Benzopyrans / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D002227:Carbazoles / Q000494:pharmacology*; D000077261:Carvedilol; D004311:Double-Blind Method; D004983:Ethanolamines / Q000494:pharmacology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D000068577:Nebivolol; D011412:Propanolamines / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000494:pharmacology; D055815:Young Adult
D000319:Adrenergic beta-Antagonists; D001578:Benzopyrans; D002227:Carbazoles; D004983:Ethanolamines; D011412:Propanolamines; D014665:Vasodilator Agents; D000068577:Nebivolol; D000077261:Carvedilol