The effect of timolol vs placebo on angina pectoris

Treatment of stable angina pectoris

Management of stable angina pectoris includes antianginal medications, medications to prevent progression of atherosclerosis, and aggressive treatment of causative risk factors. Antianginal medications commonly used include nitrates, beta-blockers, calcium channel blockers, and ranolazine. Antiplatelet agents, statins, and angiotensin-converting enzyme inhibitors are used in patients with these problems to prevent progression of atherosclerosis and/or premature cardiovascular death. Aggressive risk factor control with diet; exercise; treatment of diabetes, hypertension, and dyslipidemia; and strategies to stop smoking and reduce weight should be a part of treatment strategy in all patients. Patients with stable angina who have symptoms refractory to medical treatment usually require coronary angiography, followed by either percutaneous or surgical revascularization. Recent mechanical techniques for the treatment of refractory angina include transmyocardial laser revascularization, enhanced external counterpulsation, and spinal cord stimulation.

Haemodynamic and metabolic effects of timolol (Blocadren) on ischaemic myocardium

The effects of timolol (2.5 mg i.v.) on coronary haemodynamics and myocardial metabolism were studied in 26 patients with angina pectoris. Cardiac venous flow (CVF) was measured by thermodilution technique. Blood was sampled for metabolic studies. Angina pectoris was induced by atrial pacing and the same heart rate was regained after timolol. Metabolic ischaemia was defined as reduction in myocardial lactate extraction ratio (MLE) by at least 50% and to a ratio below 0.15. The study was completed in 22 patients, 9 of whom fulfilled the metabolic criteria for ischaemia. This subgroup did not differ from the total group in any other respect than in lactate metabolism. Beta-adrenergic blockade reduced myocardial oxygen consumption (MVO2) and CVF significantly at rest, but MVO2, CVF, myocardial glucose uptake and MLE were unchanged during pacing despite a decrease in systolic aortic pressure, ejection time and reduced myocardial free fatty acid uptake. Conclusively, timolol did not reduce MVO2 and metabolic ischaemia during pacing-induced angina.

Postinfarction use of beta-blockers in elderly patients

beta-Adrenoceptor antagonists (beta-blockers) reduce mortality and recurrent myocardial infarction (MI) in older patients after both Q-wave MI and non-Q-wave MI. The effects of beta-blockers are to: (i) reduce complex ventricular arrhythmias, including ventricular tachycardia; (ii) increase the ventricular fibrillation threshold; (iii) reduce myocardial ischaemia; (iv) decrease sympathetic tone; (v) markedly attenuate the circadian variation of complex ventricular arrhythmias: (vi) abolish the circadian variation of myocardial ischaemia; and (vii) abolish the circadian variation of sudden cardiac death or MI. beta-Blockers reduce mortality in patients with MI and complex ventricular arrhythmias. In addition, they are excellent antianginal agents. Older persons with hypertension who have had an MI should be treated initially with a beta-blocker. beta-Blockers reduce mortality in patients with: (i) diabetes mellitus who have had an MI; (ii) MI and congestive heart failure with an abnormal or normal left ventricular ejection fraction; and (iii) MI and an asymptomatic abnormal left ventricular ejection fraction. Severe congestive heart failure, severe peripheral arterial disease with threatening gangrene, greater than first degree atrioventricular block, hypotension, bradycardia, lung disease with bronchospasm, and bronchial asthma are contraindications to treatment with beta-blockers.

Once daily timolol in the prophylaxis of angina pectoris

The clinical efficacy of timolol given once and twice daily was compared in the management of angina pectoris. Following a 2-week entry period, 16 normotensive male subjects with stable angina and proven myocardial ischaemia received timolol 10 mg twice daily, or 20 mg every morning for 1 month followed by 1 month on crossover therapy. All were exercised on separate days in random order 1 hr after administration of 10 mg, 1 hr after administration of 20 mg, 13 hr after administration of 10 mg and 25 hr after administration of 20 mg. In spite of significant differences in the maximum heart rates, rate pressure products and maximum lateral ST segment depression between the once and twice daily regimes, the maximal walking times were not significantly different (P greater than 0.10) and attack rates for angina and trinitrin consumption were similar (P greater than 0.45; P greater than 0.05). This evidence suggests that timolol is as effective in dosage of 20 mg taken once daily as half the dose taken twice daily in the symptom management of angina pectoris.

Enhancement of salvage of reperfused myocardium by early beta-adrenergic blockade (timolol)

Although reperfusion of severely ischemic myocardium with thrombolytic agents or surgery has shown reduction in infarct size, the time after coronary occlusion during which reperfusion can salvage ischemic myocardium is limited. To determine whether beta-adrenergic blockade could enhance the salvage of ischemic myocardium by reperfusion, the left anterior descending coronary artery was occluded in 18 anesthetized dogs. An in vivo area at risk was determined by injecting technetium-99m-labeled albumin microspheres into the left atrium 5 minutes after occlusion and carrying out radioautography to define the poorly perfused tissue. Fifteen minutes after coronary occlusion, the dogs were randomized either to a control (saline-treated) group (n = 8) or to a timolol-treated group (n = 10). Timolol was administered until a decrease of 20% in heart rate or blood pressure occurred (mean total dose = 0.85 +/- 0.22 mg/kg +/- standard error of the mean). Coronary occlusion was maintained for 3 hours and was followed by 3 hours of reperfusion in both groups. At the end of 6 hours, infarct size was defined by triphenyltetrazolium chloride staining and masses of infarct and risk were calculated. Percent left ventricular mass at risk was similar for both groups (control = 20.9 +/- 2.4%, timolol-treated = 23.7 +/- 2.1%, p = not significant). Mass of necrosis/mass at risk was significantly smaller in the timolol-treated reperfusion group (27.3 +/- 2.7%) versus saline reperfusion alone (46.5 +/- 5.6%) (p less than 0.005). Thus, beta-adrenergic blockade administered early after coronary occlusion results in substantial enhancement of the salvage achieved by reperfusion alone.

Effects of propranolol and timolol on left ventricular volumes during exercise in patients with coronary artery disease

The hemodynamic effects of beta-receptor blocking agents on the ejection fraction of patients with coronary artery disease during exercise have been studied previously using radionuclide techniques. Left ventricular volume measurements and the peak systolic pressure/end-systolic volume (PSP/ESV) index have been shown to be variables of left ventricular function that are less influenced by preload and afterload than is ejection fraction. Left ventricular volumes and PSP/ESV were therefore measured in 18 patients with proven coronary artery disease in the control state and after 2 weeks of daily maintenance therapy with either 240 mg propranolol or 60 mg timolol. Values at rest and during symptom-limited upright exercise were compared using the first pass technique and a multicrystal scintillation camera. Left ventricular volumes were measured by the area-length method. Because there was no difference between the propranolol and timolol groups, the results for both groups were combined. The ejection fraction at rest after beta-receptor blocker treatment was not significantly different from pretreatment measurements because of an increase in both end-diastolic and end-systolic volumes (p less than 0.01). However, the value for peak systolic pressure/end-systolic volume (PSP/ESV) index at rest was lower after treatment. The exercise ejection fraction was greater after treatment (p less than 0.01), owing to an increase in end-diastolic volume and unchanged end-systolic volume. In addition, there was a significant improvement in the directional change in the PSP/ESV ratio between rest and exercise from pretreatment to treatment (-1.1 +/- 2.5 to +0.2 +/- 1.2, p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of timolol on exercise-induced reduction in regional ejection fraction in patients with coronary artery disease

In order to evaluate the effects of timolol, a new beta-adrenergic blocking agent, on exercise-induced left ventricular wall motion abnormalities, we studied nine patients with chronic, angiographically-documented coronary artery disease. A computerized technique for determining apical, anteroseptal and inferoposterior regional ejection fractions during gated radionuclide ventriculography was used to assess left ventricular dysfunction. During exercise prior to the administration of timolol, the apical regional ejection fraction fell from 0.62 +/- 0.08 to 0.51 +/- 0.08 (p less than .01). The anteroseptal ejection fraction fell from 0.50 +/- 0.08 to 0.41 +/- 0.05 (p less than .05), and the inferoposterior ejection fraction fell from 0.75 +/- 0.10 to 0.59 +/- 0.06 (p less than .05). Three days after beginning therapy with 10-30 mg of timolol, this reduction was markedly attenuated. The apical ejection fraction fell from 0.59 +/- 0.09 to 0.54 +/- 0.08 (p = NS), the anteroseptal ejection fraction fell from 0.49 +/- 0.07 to 0.47 +/- 0.18 (p = NS) and the inferoposterior ejection fraction fell from 0.62 +/- 0.06 to 0.59 +/- 0.07 (p = NS). Furthermore, several individual regions showed increases in ejection fraction. This study demonstrates a previously unreported and beneficial anti-ischemic effect of timolol.

Oxyhaemoglobin equilibrium and chronic beta-adrenoceptor blockade in coronary heart disease

In 20 patients with coronary heart disease the effect of long-term beta-adrenergic receptor blockade on the haemoglobin oxygen equilibrium was investigated. Study patients received alprenolol 200 mg twice daily for 12-41 months (mean: 24 months) as a secondary preventive measure following a myocardial infarction. While on and again following gradual withdrawal of alprenolol, the patients performed a maximum bicycle ergometer test. Haemoglobin oxygen affinity as expressed by the P50 value, 2,3-diphosphoglycerate (2,3-DPG) and carbon monoxide haemoglobin were measured before and following exercise. Pre-exercise P50 decreased from 25.2 +/- 0.3 mm Hg (mean +/- s.e. mean) while on beta-adrenoceptor blocker to 24.6 +/- 0.4 mm Hg in the off-treatment state (P less than 0.05). Five minutes after stopping exercise P50 was 25.1 +/- 0.3 in patients taking alprenolol as compared to 24.7 +/- 0.3 after withdrawal of the drug (P less than 0.01). It is concluded that the slight decrease in haemoglobin oxygen affinity in long-term treatment with alprenolol, which is observed in the present study probably is without clinical bearing. The question should be further elucidated by analysis of coronary sinus blood samples.

Electrophysiologic effects of intravenous timolol

We evaluated the electrophysiologic effects and dose response of the long-acting beta-blocking drug timolol given intravenously to 12 patients during intracardiac electrophysiologic study. Electrophysiologic parameters were measured during control and immediately, 30 minutes, and 48 hours following infusion. Significant changes in electrophysiologic parameters were only observed in the five patients (Group B) who received 0.05 mg/kg and not in the seven patients who received 0.02 mg/kg (Group A). In Group B patients immediately after timolol infusion sinus cycle length increased from 840 +/- 254 msec to 1048 +/- 63 msec (P less than 0.01), A-H interval during normal sinus rhythm increased from 94 +/- 42 msec to 101 +/- 45 msec (P less than 0.05), paced cycle length to A-V nodal Wenckebach increased from 370 +/- 45 msec to 430 +/- 76 msec (P less than 0.05), and A-V nodal effective refractory period increased from 284 +/- 63 msec to 360 +/- 83 msec (P less than 0.01). Significant increases in these electrophysiologic parameters were also noted at 30 minutes following timolol infusion. Other conduction times, atrial and ventricular refractory periods, and corrected sinus node recovery. time were unaltered by timolol. All electrophysiologic parameters returned to control in 48 hours. No adverse effects were observed. We conclude that intravenous timolol in doses of 0.05 mg/kg significantly increases sinus cycle length and prolongs A-V nodal conduction and refractoriness, demonstrates peak effects immediately after intravenous administration, and is well tolerated.

Antianginal efficacy and improved exercise performance with timolol. Twice-daily beta blockade in ischemic heart disease

Antianginal efficacy and improved exercise performance with timolol, a new beta-adrenergic blocking agent, was assessed in 23 patients with chronic stable angina pectoris in an 11-week double-blind, placebo-controlled study. Twenty-two of the 23 subjects completed the open-label phase of this investigation (weeks 0 to 6) while receiving 10 to 30 mg of timolol twice daily to optimize exercise capacity. Weekly anginal episodes and nitroglycerin consumption declined from 8.9 +/- 9.1 episodes/week and 8.1 +/- 10.6 tablets/week, respectively, with placebo to 2.7 +/- 5.2 episodes/week and 2.6 +/- 6.0 tablets/week with optimal timolol dose (p less than 0.05). Resting heart rate (HR) and systolic blood pressure (SBP) also decreased from 75.2 +/- 14.0 beats/min and 139.1 +/- 15.7 mm Hg with placebo to 55.1 +/- 8.9 beats/min and 130.5 +/- 15.9 mm Hg with timolol (p less than 0.05). Peak exercise HR, peak exercise SBP, and peak exercise double product (HR X SBP) were significantly (p less than 0.05) reduced when evaluated 12 to 13 hours after administration of timolol compared with placebo (101.5 +/- 21.1 beats/min verus 193.3 +/- 96.2 beats/min, 161.5 +/- 26.7 mm Hg versus 175.6 + 20.8 mm Hg, and 16.6 +/- 5.1 X 10(-3) versus 21.7 +/- 5.4 X 10(-3), respectively). Exercise duration was prolonged from 263.3 +/- 90.2 seconds to 330.3 +/- 73.9 seconds (p less than 0.05), while time to onset of 1 mm S-T segment depression was delayed in 15 patients from 231.8 +/- 86.4 seconds to 298.7 +/- 68.4 seconds (p less than 0.05). During the double-blind phase (weeks 7 to 10), 8 subjects received timolol and 11 patients received placebo. Nitroglycerin consumption at weeks 8 and 10 and anginal frequency at week 8 were unchanged compared with initial placebo treatment. Resting HR, peak exercise HR, and peak exercise double product were significantly attenuated at weeks 8 and 10 in timolol patients compared with their initial placebo exposure. However, these variables were unchanged in placebo subjects compared with their initial placebo therapy. Exercise duration was again prolonged at week 8 in timolol subjects compared with initial placebo results (315.1 +/- 61.2 seconds versus 261.3 +/- 68.8 seconds, p less than 0.05), but not at week 10. Placebo patients demonstrated no difference at week 8 or 10 in exercise performance compared with initial placebo treatment. Timolol twice daily, therefore, is potentially useful in some patients with angina pectoris. Other patients may, however, require a shorter dose interval for optimal angina control and maximal improvement in exercise capacity.

Pharmacokinetics, mechanisms of action, indications, and adverse effects of timolol maleate, a nonselective beta-adrenoreceptor blocking agent

Timolol, a nonselective beta-adrenoreceptor blocking agent without intrinsic sympathomimetic or membrane stabilizing activity, has been shown effective in the treatment of angina and hypertension. It is particularly useful in patients with stable angina pectoris and patients with mild to moderate hypertension. In both of these conditions, timolol appears to be comparable to propranolol. A recent study has suggested that timolol reduces mortality and reinfarction rate in patients who have recently had a myocardial infarction. When given topically timolol reduces intraocular pressure in patients with open-angle glaucoma; the drug may be used as the primary agent or as an adjunct to standard therapy. Careful selection of patients will reduce the frequency of adverse effects due to beta-receptor inhibition. Thus, timolol should not be used in patients who are predisposed to asthmatic bronchitis or cardiac failure, and it should be used with caution in patients with peripheral vascular disease or diabetes mellitus.