Drugs online research references
Jpn Circ J. 1993 Aug;57(8):760-8.
Age-related changes of sinus node function and autonomic regulation in subjects without sinus node disease--assessment by pharmacologic autonomic blockade.
Kuga K, Yamaguchi I, Sugishita Y.
Department of Internal Medicine, University of Tsukuba, Ibaraki, Japan.
To assess the relationship between aging and autonomic regulation of sinus node function, 56 subjects of various ages (range 14-75 years, mean 43 +/- 19 years) without sinus node disease were studied. Heart rate, corrected sinus node recovery time and sinoatrial conduction time were measured before (basic) and after (intrinsic) pharmacologic autonomic blockade (propranolol + atropine i.v.). Percent chronotropies of the above parameters were calculated by a modified Jordan's method. Basic heart rate and basic corrected sinus node recovery time did not vary with age (r = -0.15, r = 0.08, respectively), while basic sinoatrial conduction time tended to increase with age (r = 0.32, p < 0.05). Intrinsic heart rate decreased (r = -0.76, p < 0.001), and intrinsic corrected sinus node recovery time and intrinsic sinoatrial conduction time both increased with age (r = 0.55, p < 0.001; r = 0.56, p < 0.001, respectively). The younger the subject, the more negative the percent chronotropies of the above parameters were, and the percent chronotropies correlated positively with age (r = 0.68, p < 0.001; r = 0.52, p < 0.001 and r = 0.34, p < 0.05, respectively). In conclusion, intrinsic sinus node functions deteriorated with age. Furthermore, parasympathetic tone on the sinus node functions decreased with age, which may compensate for age-related deterioration of intrinsic sinus node function.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8355393&dopt=Abstract
Eur J Clin Pharmacol. 1993;44(5):489-92.
The effect of age on diurnal variation in the pharmacokinetics of propranolol in hypertensive subjects.
Shiga T, Fujimura A, Tateishi T, Ohashi K, Ebihara A.
Department of Clinical Pharmacology, Jichi Medical School, Tochigi, Japan.
There is diurnal variation in the absorption rate of propranolol in younger subjects. This study was undertaken to examine the effect of age on the chronopharmacokinetics of propranolol. We gave 20 mg of propranolol orally to 13 younger and 11 older hypertensive subjects at 09.00 h (day study) or 21.00 h (night study) in a cross-over design. Plasma concentrations of propranolol and its metabolites, 4-hydroxypropranolol and naphthoxylactic acid, were determined just before and at 0.5, 1, 1.5, 2, 3, 4, 6, 12, and 24 h after dosage. In the younger subjects the absorption rate constant (ka) of propranolol and its maximum plasma concentration (Cmax) were significantly higher and the time to maximum concentration (tmax) was significantly shorter in the day than at night. There were similar time-variant changes in Cmax and tmax for 4-hydroxypropranolol and naphthoxylactic acid. In contrast, there were no time-variant changes in ka, Cmax and tmax of propranolol and its metabolites in the older subjects. These results suggest that propranolol is absorbed more rapidly after morning dosing than after night-time dosing in younger but not in older subjects. Based on these findings, we speculate that the time-variance in the absorption rate or first-pass elimination, or both, of propranolol diminish with age.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8359189&dopt=Abstract
Am Heart J. 1993 Sep;126(3 Pt 1):587-93.
Effect of antianginal agents on the relationship between rate-pressure product and myocardial oxygen uptake.
Kodama Y, Yokota M, Miyahara T, Matsunami T, Sobue T, Saito H.
First Department of Internal Medicine, Nagoya University School of Medicine, Japan.
To evaluate the effects of antianginal agents on the correlation between rate-pressure product and myocardial oxygen uptake, multistage supine leg exercise tests were performed by 21 patients with stable effort-induced angina pectoris before and after administration of antianginal drugs (a calcium channel blocker of the dihydropyridine class [10 mg of nisoldipine orally] in 11 patients and a beta-blocker [0.2 mg/kg of propranolol intravenously] in 10 patients). The rate-pressure product was closely correlated with myocardial oxygen uptake before and after administration of each drug. However, the slope of the regression line of rate-pressure product (X) and myocardial oxygen uptake (Y) became significantly steeper after the calcium channel blocker administration, and the Y-intercept was significantly increased by administration of the beta-blocker. Myocardial oxygen uptake was increased after administration of the calcium channel blocker and the beta-blocker compared with control values at corresponding rate-pressure product. These observations should be considered when the rate-pressure product is used to predict myocardial oxygen uptake in patients with angina pectoris who are receiving antianginal drugs.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8362713&dopt=Abstract
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