Pharmacological and hemodynamic profile of nebivolol, a chemically novel, potent, and selective beta 1-adrenergic antagonist.

The pharmacological profile of nebivolol (N), a chemically novel beta-adrenergic antagonist, was assessed in investigations on isolated tissues, awake spontaneously hypertensive rats (SHR), closed-chest anesthetized dogs, and humans. In vitro, N was found to be a potent antagonist of beta 1-adrenergic receptors (A2 value, 5.8 X 10(-9) M) and only a weak beta 2-adrenergic antagonist (A2 value, 1.7 X 10(-6) M). The selectivity for the beta 1-adrenergic receptor was higher for N than for any of the reference compounds. In dogs--similarly with atenolol--N was more potent in blocking the isoprenaline (I)-induced increases in left ventricular performance than the I-induced decrease in arterial pressure. In dogs, as compared with propranolol, N (0.025 and 0.01 mg.kg-1 i.v.) increased cardiac output and stroke volume, lowered systemic vascular resistance, and had no significant effect on the variables related to left ventricular contraction. In contrast to other beta-adrenergic antagonists, N acutely lowered arterial blood pressure in SHR (1.25 mg.kg-1 i.p.) and in hypertensive patients (1 oral dose of 5 mg) for several hours. In healthy volunteers N (5 mg) lowered systemic vascular resistance during daily oral treatment and did not negatively affect left ventricular function. In conclusion, N is a potent and selective beta 1-adrenergic blocking agent with an interesting hemodynamic profile. In hypertensive subjects and SHR, a single dose lowers arterial blood pressure for substantial periods of time.

Inhibitory effect of lidoflazine on contractions of isolated canine coronary arteries caused by norepinephrine, 5-hydroxytryptamine, high potassium, anoxia and ergonovine maleate.

Experiments were performed on isolated coronary arteries to determine whether or not lidoflazine, an agent reported to be beneficial in the treatment of angina pectoris, is effective in antagonizing coronary vasoconstriction. Segments of canine circumflex and right coronary arteries were suspended in organ chambers filled with aerated Krebs-Henseleit solution (37 degrees C) for continuous isometric tension recordings. Dose-dependent contractions were obtained with norepinephrine (in presence of propranolol) and 5-hydroxytryptamine; these contractile responses were antagonized by phentolamine and methysergide, respectively. Lidoflazine caused long-lasting, and dose-dependent inhibition of the responses to both norepinephrine and 5-hydroxytryptamine. High K+ solution (30 mM) caused sustained contraction of the coronary segments; these responses were depressed in a dose-dependent manner by lidoflazine. Lidoflazine slightly augmented relaxations caused by adenosine. Addition of Ca++ to the bath solution partially reversed the inhibitory effect of lidoflazine, which indicates that the compounds acts by inhibiting the influx of extracellular Ca++. Segments incubated in solution containing 20 mM K+ and subjected to anoxia exhibited transient contractions which were inhibited by lidoflazine. Ergonovine maleate caused contractures of the coronary arteries which also were antagonized in a dose-dependent manner by lidoflazine. These experiments demonstrate the ability of lidoflazine to counteract contractions of coronary vascular smooth muscles caused by factors which may be involved in the etiology of coronary vasospasm.

Oxatomide, a new orally active drug which inhibits both the release and the effects of allergic mediators.

Oxatomide is a new potent inhibitor of anaphylactic and allergic reactions. After oral administration, the compound both inhibits the release of endogenous histamine and prevents the effects of exogensous histamine, at comparable doses. The combination of these effects appears to be the basis of the effectiveness of oxatomide in allergic reactions and may lead to clinical application different from classical antihistaminics and from cromoglycate.