Does oral alprazolam affect ventilation? A randomised, double-blind, placebo-controlled trial.
The respiratory effects of benzodiazepines have been controversial. This investigation aimed to study the effects of oral alprazolam on ventilation. In a randomised, double-blind cross-over protocol, 20 healthy men ingested 1 mg of alprazolam or placebo in random order, 1 week apart. Ventilation was unobtrusively monitored by inductance plethysmography along with end-tidal PCO(2) and pulse oximetry 60-160 min after drug intake. Subjects were encouraged to keep their eyes open. Mean +/- SD minute ventilation 120 min after alprazolam and placebo was similar (6.21 +/- 0.71 vs 6.41 +/- 1.12 L/min, P = NS). End-tidal PCO(2) and oxygen saturation did also not differ between treatments. However, coefficients of variation of minute ventilation after alprazolam exceeded those after placebo (43 +/- 23% vs 31 +/- 13%, P < 0.05). More encouragements to keep the eyes open were required after alprazolam than after placebo (5.2 +/- 5.7 vs 1.3 +/- 2.3 calls, P < 0.05). In a multiple regression analysis, higher coefficients of variation of minute ventilation after alprazolam were related to a greater number of calls. Oral alprazolam in a mildly sedative dose has no clinically relevant effect on ventilation in healthy, awake men. The increased variability of ventilation on alprazolam seems related to vigilance fluctuations rather than to a direct drug effect on ventilation.
Psychiatry Division, University Hospital Zürich, University of Zurich, Zurich, Switzerland.
G E
GE
Carraro
E W
EW
Russi
S
S
Buechi
Konrad E
KE
Bloch
D000328:Adult; D000525:Alprazolam / Q000494:pharmacology*; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D002245:Carbon Dioxide / Q000378:metabolism; D018592:Cross-Over Studies; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D010092:Oximetry / Q000379:methods; D010100:Oxygen / Q000097:blood; D010991:Plethysmography / Q000379:methods; D012123:Pulmonary Ventilation / Q000187:drug effects*; D012044:Regression Analysis; D012119:Respiration / Q000187:drug effects; D055815:Young Adult
D014151:Anti-Anxiety Agents; D002245:Carbon Dioxide; D010100:Oxygen; D000525:Alprazolam