| Reference | 1. Clin Interv Aging. 2014 Oct 13;9:1741-5. doi: 10.2147/CIA.S69420. eCollection 2014.<br />
Bradyarrhythmias secondary to topical levobunolol hydrochloride solution.<br />
Lin L(1), Wang Y(1), Chen Y(1), Liu M(1).<br />
Author information:<br />
(1)Geriatric Department, Peking University First Hospital, Beijing, People's Republic of China.<br />
An 88-year-old man was admitted with fatigue, dizziness, and heart palpitations. Both the electrocardiogram and Holter confirmed the existence of sinus bradycardia and sinus arrest. One hour prior to the onset of symptoms, he received levobunolol hydrochloride solution topically. The levobunolol hydrochloride solution was discontinued and the bradycardia resolved. He was diagnosed as having intermittent sinus bradycardia and sinus arrest, induced by topical β-blocker therapy. Levobunolol hydrochloride solution is an effective therapy for ocular hypertension, probably by reducing aqueous fluid production. However, it can induce cardiac side effects such as bradyarrhythmia and should be used with caution in elderly patients or patients with cardiac disease.<br />
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2. J Ocul Pharmacol Ther. 2002 Apr;18(2):105-13.<br />
A comparison of the efficacy and tolerability of 0.5% timolol maleate ophthalmic gel-forming solution QD and 0.5% levobunolol hydrochloride BID in patients with ocular hypertension or open-angle glaucoma.<br />
Halper LK(1), Johnson-Pratt L, Dobbins T, Hartenbaum D.<br />
Author information:<br />
(1)Merck & Co., Inc., West Point, Pennsylvania, USA.<br />
The purpose of this study was to compare the ocular hypotensive efficacy and tolerability of 0.5% timolol maleate ophthalmic gel-forming solution (timolol gel) and 0.5% levobunolol hydrochloride (levobunolol). This was a randomized, double-masked, multi-center, active-controlled, 2-period, crossover study. After a 3-week, single-masked placebo run-in phase, patients with ocular hypertension or open-angle glaucoma and an intraocular pressure (IOP) > or = 22 mmHg were randomized to receive timolol gel QD or levobunolol BID for 6 weeks followed by a 3-week, placebo washout period. Patients were then crossed over to the alternate treatment for 6 weeks. IOP and heart rate (HR) were measured at 3 and 6 weeks after the start of therapy with either timolol gel or levobunolol. Of 133 patients randomized, 116 received both treatments. Timolol gel QD was comparable to levobunolol BID in reducing trough and peak IOP. At trough, HR was marginally increased with timolol gel and was decreased with levobunolol (p = < 0.001). At peak, HR was decreased with both treatments, but the decrease was significantly less with timolol gel than with levobunolol (p = 0.049). Significantly more patients experienced at least one adverse event (p = 0.024), adverse events related to special senses (p = 0.002), and burning and stinging (p < 0.001) with levobunolol compared to timolol gel. The study demonstrates that timolol gel QD has IOP-lowering effects comparable to those of levobunolol BID with fewer adverse experiences and less effect on HR.<br />
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3. J Tongji Med Univ. 1997;17(2):90-3.<br />
The effect of levobunolol hydrochloride on the calcium and potassium channels in isolated ventricular myocytes of guinea pig.<br />
Tang M(1), Chen L, Wei W, Yang L, Wang T, Liu Z, Hu X, Sun H, Luo H.<br />
Author information:<br />
(1)Department of Physiology, School of Basic Medical Sciences, Tongji Medical University, Wuhan.<br />
The effects of levobunolol hydrochlorid (Bun) on the type L calcium channel currents (ICA) and delayed rectifier potassium channel currents (IK) in isolated ventricular myocytes of guinea pig were studied by using patch clamp whole cell recording techniques. The results were showed that: 1) Bun caused a dose dependent decrease in ICA and a dose-dependent increase in IK of the ventricular myocytes. The threshold concentrations of Bun for ICA and IK were 10(-8) mol/L and 10(-7) mol/L respectively. The maximum effective concentration of Bun for bot ICA and IK was 3×10(-5) mol/L, and half-maximal concentration was 3×10(-6) mol/L; 2) IK was blocked by 2×100(-6) mol/L tetraethylammonium (TEA). A concentration of 3×10(-6) mol/L Bun showed a decreasing effect on the ICA as revealed by the current-voltage relationship curve, i.e., Bun caused an elevation of the curve;3) When ICA was blocked by 2×10(-6) mol/L Isoptin (Verapamil), at a concentration of 3×10(-6) mol/L Bun showed an increasing effect on IK and the effect could be blocked by TEA. The above-mentioned results indicated that Bun had an inhibitory effect on ICA and a fascilitatory effect on IK. The results suggested that the molecular mechanisms of antihypertensive, heart rate slowing the beta -receptor blocking effects of Bun might be due to decrease of ICA and increase of IK.<br />
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