Gender-related differences exist in the pharmacokinetics of metoprolol enantiomers, resulting in greater drug exposure in female subjects. However, concentration-effect relationships did not differ between men and women. Therefore the observed differences in drug effects were the result of gender-specific differences in metoprolol pharmacokinetics.
Studies demonstrate a positive correlation between hyperhomocysteinemia and atherosclerosis. The treatment of choice for hyperhomocysteinemia is folic acid. Although the optimal dose is not known, 650 microg/d is the minimum effective dose. To date, no studies have assessed the effects on morbidity and mortality when treating high homocysteine concentrations in atherosclerotic patients.
This study was conducted to determine whether gender differences exist in adrenergic receptor sensitivity and baroreflex response. Adrenergic receptor sensitivity was assessed by administering sequentially increasing intravenous doses of phenylephrine and isoproterenol. Baroreflex sensitivity was determined from the slope of pulse intervals plotted against phenylephrine-induced rise in systolic blood pressure (SBP). Drug-induced changes in heart rate, blood pressure, and brachial artery diameter were measured and statistically compared. Women required a lower infusion rate of phenylephrine to increase SBP by 20 mmHg from baseline. There were no statistically significant gender-related differences in baroreflex sensitivity. The dose of isoproterenol needed to increase heart rate by 25 beats per minute from baseline also did not differ significantly between groups. Percent changes from baseline in brachial artery diameters in response to phenylephrine also were similar between groups. These data suggest that women may have greater alpha-adrenergic receptor sensitivity than men, whereas beta1-adrenergic receptor sensitivity is similar between genders. A trend toward a greater baroreflex sensitivity in men than in women was also observed. This study also provides evidence for a possible relationship between adrenergic receptor sensitivity and baroreflex sensitivity.
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