An eighteen months' study of the clinical response to metoprolol, a selective beta1-receptor blocking agent, in patients with angina pectoris

Fundus autofluorescence and ellipsoid zone (EZ) line width can be an outcome measurement in RHO-associated autosomal dominant retinitis pigmentosa

PURPOSE

To evaluate the progression of retinitis pigmentosa (RP) due to mutations in rhodopsin (RHO) by measuring the short-wavelength autofluorescence (SW-AF) increased autofluorescence ring and ellipsoid zone (EZ)-line width.

METHODS

Fundus autofluorescence (FAF) and spectral domain optical coherence tomography (SD-OCT) images were obtained from 10 patients with autosomal dominant RP due to mutations in the RHO gene. Measurements of ring area on FAF images, as well as the EZ line width on SD-OCT images and horizontal, vertical diameter, were performed by two independent masked graders.

RESULTS

The ring area decreased by a rate of 0.6 ± 0.2 mm² per year. We observed that the EZ line width decreased by an average of 152 ± 37 μm per year, while the horizontal and vertical diameters decreased by 106 ± 35 μm and 125 ± 29 μm per year, respectively. Progression rates were similar between eyes.

CONCLUSIONS

We observed SW-AF ring constriction and a progressive loss of EZ line width over time.

The antianginal efficacy and tolerability of controlled-release metoprolol once daily: a comparison with conventional metoprolol tablets twice daily

In a randomized, double-blind, cross-over study treatment with a new controlled-release (CR) preparation of metoprolol, given once daily, was compared with treatment with conventional metoprolol tablets, given twice daily, in 115 patients with stable effort angina pectoris. The patients were treated with 100 mg/day or 200 mg/day, depending on their previous beta-blocker dose. Antianginal efficacy was estimated by counting the number of anginal attacks, by noting the consumption of nitroglycerin tablets, and by exercise tolerance testing. Adverse effects were recorded by a standardized questionnaire. When all patients were analysed together there were no differences in antianginal efficacy between the two treatment regimens. However, when the group taking 200 mg daily was analysed separately better exercise tolerance was found during metoprolol CR therapy, as measured by onset of chest pain and ST-segment change, compared with conventional metoprolol therapy. The two formulations were well tolerated. When given once daily in a total daily dose of 100 mg, the CR preparation induced less adverse effects than the conventional tablets, 50 mg twice daily. It was concluded that the new metoprolol CR preparation, given once daily, possesses the same antianginal efficacy as conventional metoprolol tablets, given twice daily, and may be better tolerated in patients susceptible to side-effects. The antianginal effect of metoprolol CR, 200 mg/day, may be greater over 24 h than that produced by conventional metoprolol tablets, 100 mg twice daily.

Electrophysiologic effects of intravenous metoprolol

We evaluated the electrophysiologic effects of intravenous metoprolol, a selective beta-1-blocking agent, in 12 patients. Electrophysiologic parameters were measured during the control period, immediately following, and 4 to 6 hours after infusion of 0.15 mg/kg. Metoprolol serum concentration was serially measured in 6 of the 12 patients. Immediately after metoprolol infusion, the sinus cycle length increased by 20% from 738 +/- 166 msec to 885 +/- 181 msec (p less than 0.01), AH interval during sinus rhythm increased by 34% from 83 +/- 27 msec to 112 +/- 37 msec (p less than 0.01), and antegrade atrioventricular (AV) nodal Wenckebach cycle length increased by 20% from 360 +/- 188 msec to 432 +/- 199 msec (p less than 0.01). Sinus node recovery time and sinoatrial conduction time did not become abnormally prolonged in any patient. His-Purkinje conduction was unaltered. High atrial and ventricular refractory periods were modestly increased (less than 15 msec); the increase in refractoriness reached statistical significance when repeat measurements were made at 4 to 6 hours. No adverse effects were noted. Metoprolol serum concentration at the time of peak measured electrophysiologic effect was 54.6 +/- 15.2 ng/ml. We conclude that at this dose, intravenous metoprolol significantly prolongs sinus cycle length and AV nodal conduction, may modestly increase atrial and ventricular refractoriness, and appears to have electrophysiologic potency similar to propranolol. It is well tolerated following intravenous administration and may be of particular value in the acute treatment of supraventricular tachycardia when beta-receptor selectivity is desired.

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.

The use of a selective beta-adrenergic receptor blocker for the preoperative preparation of thyrotoxic patients

Metoprolol, a cardioselective beta-blocker, was used in two asthmatic, thyrotoxic patients in preparation for thyroidectomy. Adequate reduction in resting heart rate was achieved in both individuals without inducing clinically significant airway obstruction. Beta-1-blockade can be selectively employed in this clinical setting, but patients should be hospitalized and closely monitored for adverse effects on pulmonary function. Metoprolol therapy in patients with reversible airway obstruction is discussed with reference to recent studies on relative cardioselectivity.

Comparison of the pharmacodynamic and pharmacokinetic profiles of single and multiple doses of a commercial slow-release metoprolol formulation with a new Oros delivery system

1 A new osmotic pressure mediated delivery system for metoprolol (Lopresor Oros) has been evaluated by measuring the haemodynamic effects and pharmacokinetics after single and multiple oral dosing in young healthy volunteers. 2 Similar studies have been carried out in the same group using equivalent single and multiple oral doses of the commercial slow-release preparation (Slow Lopresor). 3 The new osmotic delivery system produces a more uniform haemodynamic response: a plateau metoprolol concentration in plasma is reached about 6 h after dosing and is maintained for 10 h.

A clinical evaluation of sustained release metoprolol durules in the treatment of angina pectoris

A clinical comparison of the sustained release form of metoprolol, consisting of a 200 mg metoprolol durule, with 100 mg conventional metoprolol twice daily, has been carried out to assess the therapeutic control of ten patients with stable angina pectoris. Objective measurements of heart rate, blood pressure, and ECG recordings were assessed during exercise on a bicycle ergometer. Ten patients completed the 8-week double-blind study. There were similar changes in heart rate and blood pressure at rest and during exercise, both at 2 h and at 12 and 24 h postdose. Although similar exercise tolerance was achieved on both regimes, there was significantly less ST-segment depression at 24 h post durule, in comparison with the 12 h post conventional metoprolol reading, suggesting that metoprolol durules produce a more effective reduction in the degree of myocardial ischemia.

The effect of beta-adrenoceptor blockade on factors affecting exercise tolerance in normal man

1 We have studied the effects of single oral doses of 80 mg propranolol and 100 mg metoprolol on the cardiovascular and respiratory responses to progressive exercise in nine healthy men in double-blind, placebo-controlled experiment. As judged by their effects on exercise heart rate and cardiac output the doses of the two drugs used were equivalent. 2 Beta-adrenoceptor blockade reduced oxygen consumption by 3.5% over the whole work range with an increase in the respiratory exchange ratio of 0.056 units. Carbon dioxide production and exercise ventilation were unchanged. The two drugs had similar effects. Possible mechanisms for these observations are discussed. 3 Perceived exertion during exercise was increased by both the beta-adrenoceptor blocking drugs and this may be of relevance to the symptom of fatigue reported by patients on these drugs. Endurance, assessed as either total work done or maximal work achieved, was reduced by 15%.

Effect of beta-adrenergic blockade on haemodynamic responses to dynamic and isometric exercise in angina pectoris

The effect of treatment for 1--4 weeks with metoprolol, a beta 1-selective blocking agent, or alprenolol, on the heart rate and blood pressure response to isometric exercise was studied in two groups of 12 patients with angina. Measurements were made during the peak effect of metoprolol 10, 40 or 50 mg, and alprenolol 200 mg as Aptin Durules. After 1 min of sustained handgrip at 50% of maximal voluntary contraction, systolic (6--15%) and diastolic (8--12%) blood pressure after both drugs was significantly lower than without any beta-blockade; Heart rate was decreased by 19--22% by metroprolol but not by alprenolol. The blood pressure rise during handgrip was not attenuated by either drug. The rise in heart rate was significantly reduced (by 36--50%) by metoprolol 40 and 50 mg and alprenolol 200 mg. No patient experienced angina during handgrip. In contrast, all but one were restricted by angina during bycycle exercise without treatment, at a level that produced the same increase in heart rate as the handgrip test, vis. 3 min at a load of 33 W). The cardiovascular response to sustained handgrip is too small to provide a useful challenge for determinatin of the anti-anginal efficacy of drugs. However, slight ECG changes of ischaemia did occur during handgrip, which were reversed by beta-blockade.

Metoprolol: a review of its pharmacological properties and therapeutic efficacy in hypertension and angina pectoris

Metoprolol is a beta1-selective adrenoceptor blocking drug. In hypertension, its duration of effect is longer than expected from its half-life and it is suitable for twice daily administration. There is some evidence that once daily administration may be possible in treating hypertension. It is similar in efficacy to other beta-adrenoceptor blocking drugs in angina pectoris and essential hypertension, when given in equiactive beta-blocking dosages. Metoprolol is well tolerated and side-effects have not proved a problem. It has some pharmacodynamic and pharmacokinetic differences from other beta-adrenoceptor blocking drugs and may prove useful in cases where these differences are shown to be clinically important.