The cardioselectivity of beta adrenoceptor antagonists

THE EFFECTS OF BISOPROLOLA SELECTIVE β1-BLOCKERON GLUCOSE METABOLISM BY LONG-TERM ADMINISTRATION IN ESSENTIAL HYPERTENSION

Bisoprolol, a beta1-selective beta-blocker, was administered to 13 patients with mild to moderate essential hypertension once daily at doses of 5-10 mg for 24 weeks, and its long-term effects on blood pressure and glucose metabolism were investigated. The systolic, diastolic and mean blood pressures were significantly reduced. At the end of the treatment period, the blood glucose level and hemoglobin A1c were not significantly different from those at baseline. In the glucose tolerance test at the end of the treatment period, the blood glucose and plasma insulin levels after a glucose load of 75 g were not significantly different at any time point, and the sums of each were not significantly different from their baseline levels. Based on these results, bisoprolol appears to be a beta1-selective beta-blocker possessing a satisfactory hypotensive effect without any adverse effects on glucose metabolism for long-term use, and is therefore a safe and useful drug for the treatment of essential hypertension.

Safety considerations in treating concomitant diseases in patients with asthma

The treatment for asthma usually involves a combination of drugs used for bronchodilation and to treat underlying airway inflammation. When asthma is severe, the regimen used to treat asthma can become quite complicated, often using as many as 3 or 4 separate pharmacological agents. As patients with asthma get older, their medication regimen can become even more complex with the development of numerous other age-related diseases requiring their own list of medications. Diseases of the joints, diseases of the eye, cardiovascular disease, neurological disease and urological problems represent the most common conditions that patients develop, at times needing medications which might interfere with asthma management. Many of these diseases require the use of nonsteroidal anti-inflammatory agents, well known to provoke wheezing in patients with intrinsic asthma, and diseases of the eye and cardiovascular system frequently require use of beta-blockers which can cause or exacerbate asthma. Managing patients with asthma who have other diseases requires constant supervision of their medication usage and careful and cautious review of the entire list of medications at each presentation.

Quantification of metoprolol beta 2-adrenoceptor antagonism in asthmatic patients by pharmacokinetic-pharmacodynamic modelling

An integrated pharmacokinetic-pharmacodynamic model was used to quantify the beta 2-blocking activity of metoprolol in seven asthmatic patients. The patients received a subcutaneous dose of terbutaline on two consecutive days. On day 1 they were pretreated with placebo and on day 2 with metoprolol 150 mg orally. Beta 2-adrenoceptor mediated changes of plasma potassium and FEV1 were related to plasma concentrations of terbutaline and racemic metoprolol. Metoprolol activity was measured as the competitive (blocking) interaction of racemic metoprolol on the terbutaline response. Plasma concentrations and effects were monitored over 7 h following terbutaline administration. Despite the relative beta 1-selectivity of metoprolol, the effects of terbutaline were considerably attenuated. The mean (racemic) metoprolol concentration that corresponds to 50% maximum metoprolol receptor occupancy (IC50) for the effects on FEV1 and hypokalemia were, respectively, 17 (+/- 8) and 22 (+/- 12) ng/ml and were not statistically discernible. We conclude that individual integrated pharmacokinetic-pharmacodynamic modelling of the concentration-effect relations of agonist and antagonist is a feasible and direct method of quantifying beta 2-blocker effects in asthmatic patients. In stable asthma patients receiving therapeutic doses of metoprolol, the terbutaline plasma concentration needs to be increased two- to four-fold to obtain the same effect on FEV1. Plasma potassium may be considered an appropriate alternative parameter to predict the effect on FEV1.