The cardiovascular, pulmonary, and ocular hypotensive effects of 0.2% brimonidine.
OBJECTIVE
To compare the cardiovascular, pulmonary, and ocular hypotensive effects of 0.2% brimonidine tartrate with those of 0.5% timolol maleate, 0.25% betaxolol suspension, and brimonidine vehicle.


METHODS
A single-center, double-masked, randomized, crossover study of 24 young, healthy men.


METHODS
Baseline heart rate, blood pressure, respiratory rate, and intraocular pressure were recorded at hour 0. At hour 2, heart rate, blood pressure, respiratory rate, and forced expiratory volume in 1 second were measured and a 15-minute treadmill test performed. Hour 0 measurements were repeated at hour 4. On four subsequent visits, we instilled one drop of a study medication into each eye after the baseline measurements at hour 0.


RESULTS
Timolol reduced resting (-5.3 to -6.5 beats/min, P < or = .004) and exercise-induced heart rate (-4.3 to -13.6 beats/min; P < or = .022) compared with brimonidine, betaxolol suspension, and brimonidine vehicle. At hour 4, brimonidine reduced resting systolic blood pressure compared with all other study medications (-5.2 to -7.3 mm Hg; P < or = .024). Timolol reduced systolic blood pressure during exercise and brimonidine reduced systolic blood pressure during recovery more than betaxolol suspension and brimonidine vehicle (-5.1 to -7.7 mm Hg; P < or = .033; and -5.4 to -6.0 mm Hg; P < or = .002, respectively). Mean respiratory rate and forced expiratory volume in 1 second were not significantly altered by any study medication. At hour 4, brimonidine lowered intraocular pressure as well as timolol and better than betaxolol suspension (-1.9 mm Hg; P < .001) or brimonidine vehicle (-1.8 mm Hg; P < .001).


CONCLUSIONS
The cardiopulmonary effects of 0.2% brimonidine were limited to a slight reduction in systolic blood pressure during recovery from exercise and at 4 hours after instillation. The ocular hypotensive effect of brimonidine was comparable to that of timolol and greater than that of betaxolol suspension in this patient population.
Nordlund
J R
JR
Wilmer Ophthalmological Institute, Baltimore, Md.
Pasquale
L R
LR
Robin
A L
AL
Rudikoff
M T
MT
Ordman
J
J
Chen
K S
KS
Walt
J
J
D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000328:Adult; D015784:Betaxolol / Q000008:administration & dosage; D000068438:Brimonidine Tartrate; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005080:Exercise Test; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007429:Intraocular Pressure / Q000187:drug effects*; D008297:Male; D008875:Middle Aged; D015814:Ocular Hypotension / Q000139:chemically induced*; D009883:Ophthalmic Solutions; D011810:Quinoxalines / Q000008:administration & dosage / Q000494:pharmacology*; D012119:Respiration / Q000187:drug effects*; D013999:Timolol / Q000008:administration & dosage
D000316:Adrenergic alpha-Agonists; D009883:Ophthalmic Solutions; D011810:Quinoxalines; D000068438:Brimonidine Tartrate; D013999:Timolol; D015784:Betaxolol