Lopressor Clinical Trials and Studies

Lopressor Information

Lopressor Clinical Trials and Studies

In controlled clinical trials, Lopressor (metoprolol tartrate), administered 2 or 4 times daily, has been shown to be an effective antianginal agent, reducing the number of angina attacks and increasing exercise tolerance. The dosage used in these studies ranged from 100 to 400 mg daily. A controlled, comparative, clinical trial showed that Lopressor (metoprolol tartrate) was indistinguishable from propranolol in the treatment of angina pectoris.

In a large (1395 patients randomized), double-blind, placebo-controlled clinical study, Lopressor (metoprolol tartrate) was shown to reduce 3-month mortality by 36% in patients with suspected or definite myocardial infarction.

Patients were randomized and treated as soon as possible after their arrival in the hospital, once their clinical condition had stabilized and their hemodynamic status had been carefully evaluated. Subjects were ineligible if they had hypotension, bradycardia, peripheral signs of shock, and/or more than minimal basal rates as signs of congestive heart failure. Initial treatment consisted of intravenous followed by oral administration of Lopressor (metoprolol tartrate) or placebo, given in a coronary care or comparable unit. Oral maintenance therapy with metoprolol tartrate or placebo was then continued for 3 months. After this double-blind period, all patients were given Lopressor (metoprolol tartrate) and followed up to 1 year.

The median delay from the onset of symptoms to the initiation of therapy was 8 hours in both the Lopressor (metoprolol tartrate) and placebo treatment groups. Among patients treated with Lopressor (metoprolol tartrate), there were comparable reductions in 3-month mortality for those treated early (<8 hours) and those in whom treatment was started later. Significant reductions in the incidence of ventricular fibrillation and in chest paid following initial intravenous therapy were also observed with Lopressor (metoprolol tartrate) and were independent of the interval between onset of symptoms and initiation of therapy.

The precise mechanism of action of Lopressor (metoprolol tartrate) in patients with suspected or definite myocardial infarction is not known.

In this study, patients treated with Lopressor (metoprolol tartrate) received the drug both very early (intravenously) and during a subsequent 3-month period, while placebo patients received no beta-blocker treatment for this period. The study thus was able to wshow a benefit from the overall metoprolol tartrate regimen but cannot separate the benefit of very early intravenous treatment from the benefit of later beta-blocker therapy. Nonetheless, because the overall regimen showed a clear beneficial effect on survival without evidence of an early adverse effect on survival, one acceptable dosage regimen is the precise regimen used in the trial. Because the specific benefit of very early Lopressor treatment remains to be defined however, it is also reasonable to administer the drug orally to patients at a later time as is recommended for certain other beta blockers.

Lopressor Information