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Betaxolol Hydrochloride Ophthalmic
CLINICAL PHARMACOLOGY
Betaxolol Hydrochloride Ophthalmic
Betaxolol Hydrochloride HCl, a cardioselective (beta-1-adrenergic) receptor blocking agent, does not have significant membrane-stabilizing (local anesthetic) activity and is devoid of intrinsic sympathomimetic action. Orally administered beta-adrenergic blocking agents reduce cardiac output in healthy subjects and patients with heart disease. In patients with severe impairment of myocardial function, beta-adrenergic receptor antagonists may inhibit the sympathetic stimulatory effect necessary to maintain adequate cardiac function.
When instilled in the eye, Betaxolol Hydrochloride Ophthalmic Solution has the action of reducing elevated as well as normal intraocular pressure, whether or not accompanied by glaucoma. Ophthalmic betaxolol has minimal effect on pulmonary and cardiovascular parameters.
Ophthalmic betaxolol (one drop in each eye) was compared to timolol and placebo in a three-way crossover study challenging nine patients with reactive airway disease who were selected on the basis of having at least a 15% reduction in the forced expiratory volume in one second (FEV1) after administration of ophthalmic timolol. Betaxolol HCl had no significant effect on pulmonary function as measured by FEV1. Forced Vital Capacity (FVC) and FEV1/VC. Additionally, the action of isoproterenol, a beta stimulant, administered at the end of the study was not inhibited by ophthalmic betaxolol. In contrast, ophthalmic timolol significantly decreased these pulmonary functions.
FEV1 † Percent Change from Baseline1
| Means | |||
| Betaxolol 1.0%a | Timolol 0.5% | Placebo | |
| 1.6 | 1.4 | 1.4 | |
| 60 Minutes | 2.3 | -25.7* | 5.8 |
| 120 Minutes | 1.6 | -27.4* | 7.5 |
| 240 Minutes | -6.4 | -26.9* | 6.9 |
| Isoproterenolb | 36.1 | -12.4* | 42.8 |
1Schoene, R. B. et al., Am. J. Ophthal. 97:86, 1984.
aTwice the clinical concentration.
bInhaled at 240 minutes; measurement at 270 minutes.
*Timolol statistically different from betaxolol and placebo (p < 0.05).
No evidence of cardiovascular beta-adrenergic blockade during exercise was observed with betaxolol in a double-masked, three-way crossover study in 24 normal subjects comparing ophthalmic betaxolol, timolol and placebo for effect on blood pressure and heart rate. Mean arterial blood pressure was not affected by any treatment; however, ophthalmic timolol produced a significant decrease in the mean heart rate.
Mean Heart Rate1
| TREATMENT | |||
| Bruce Stress Exercise Test | Betaxolol 1%a | Timolol 0.5% | Placebo |
| Minutes | |||
| 0 | 79.2 | 79.3 | 81.2 |
| 2 | 130.2 | 126.0 | 130.4 |
| 4 | 133.4 | 128.0* | 134.3 |
| 6 | 136.4 | 129.2* | 137.9 |
| 8 | 139.8 | 131.8* | 139.4 |
| 10 | 140.8 | 131.8* | 141.3 |
Generic Name: Betaxolol Hydrochloride
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