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  • pharmacodynamics  (2)
  • ECG  (1)
  • Key words Digital pulse plethysmography; nitroglycerin  (1)
  • 1
    ISSN: 1432-1041
    Keywords: Ramipril ; Piretanide ; pharmacokinetics ; pharmacodynamics ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The pharmacokinetics and pharmacodynamics of single oral doses of 5 mg ramipril and 6 mg piretanide administered separately and in combination were determined in a single blind, randomised, 3-period cross-over study in 24 healthy male volunteers. The peak plasma concentrations of ramipril and ramiprilat increased slightly (from 11.9 to 14.8 ng/ml, and from 6.39 to 8.96 ng/ml, respectively) as did the area under the plasma concentration-time curve of ramipril (0–4 h) and ramiprilat (0–24 h) (from 15.8 to 19.8 ng·ml−1·h, and from 63.4 to 74.6 ng·ml−1·h, respectively). The urinary excretion of ramiprilat also rose (from 6.82 to 7.73 % of dose) following simultaneous treatment with piretanide. These effects were probably due to reduced first-pass metabolism of ramipril/ramiprilat to inactive metabolites. The blood pressure lowering effect, the time course of inhibition of ACE activity in plasma and the concentration-response relationship for the inhibition of plasma ACE activity were not affected by piretanide. The peak plasma concentration of piretanide was somewhat reduced (from 285 to 244 ng/ml) following simultaneous treatment with ramipril. No other pharmacokinetic parameter was affected. Piretanide increased urine flow, and sodium, chloride and potassium excretion, especially during the first 2 hours following administration. These pharmacodynamic parameters were not affected by ramipril. Thus, simultaneous administration of single oral doses of ramipril and piretanide caused modest changes in the peak and average plasma concentrations of both drugs, which did not lead to detectable alterations in the pharmacodynamic parameters measured in healthy volunteers.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1041
    Keywords: Diltiazem ; PQ interval ; ECG ; bioequivalence ; therapeutic equivalence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract We studied the use of atrioventricular (AV) conduction time to assess the therapeutic equivalence of two diltiazem formulations in 20 volunteers in a double-blind, cross-over trial. ECG recording was carried out before and at several intervals after drug administration, and prolongation of the PQ interval (ΔPQ) was taken as a pharmacodynamic response. In addition, diltiazem plasma concentrations were determined in 8 subjects. The effect of diltiazem increased proportionally with the plasma concentration and could be detected up to 10 h after administration. The area under the effect-time curve (AUEC0–10), the peak effect (Emax), and the effect mean residence time (MRTE) showed significant differences. In contrast to the pharmacodynamics, the pharmacokinetic profiles of diltiazem do not vary to the same extent. We conclude that the formulations are therapeutically different. Furthermore, at the administered dose, ΔPQ appears to be a sensitive measure for assessing the electrophysiological properties of diltiazem.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 38 (1990), S. S53 
    ISSN: 1432-1041
    Keywords: nitrates ; pharmacokinetics ; pharmacodynamics ; nitrate tolerance ; isosorbide-5-mononitrate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Healthy male volunteers received three different dose regimens of a controlled-release form of isosorbide-5-mononitrate (IS-5-MN; 60 mg per tablet). Dose regimen I consisted of a single daily dose of 60 mg given for 5 days. Dose regimen 11 was started with a dose of 60 mg, followed by 30 mg 12 h later and thereafter every 8 h. The last dose, on the 5th day was again 60 mg. In dose regimen III60 mg followed by 30 mg 6 h later were administered every day for 5 days. The peripheral arterial and venous effects of IS-5-MN during the first and last dosing interval were followed by changes in the finger pulse curve, standing systolic blood pressure, heart rate, and venous distensibility. Plasma concentrations of IS-5-MN were measured frequently following the first and the last dose. Following dose regimen I all hemodynamic effects produced by the first dose were maintained during the study. The maximal plasma concentrations were about 400 ng/ml and the trough value, lower than 100 ng/ml. Following dose regimen II the hemodynamic effects of IS-5-MN and sublingual glyceroltrinitrate were completely abolished on the 5th day. Trough plasma concentrations were approximately 300 ng/ml during the entire study period. Following dose regimen III pronounced hemodynamic effects were seen on the 1st day. However, a significant attenuation of the hemodynamic effects was measured on the 5th day, when trough plasma concentrations were between 100 and 230 ng/ml. There was a significant negative correlation between the magnitude of hemodynamic effect remaining on the 5th day (measured by the area under the finger pulse curve) and the trough plasma concentration. Thus, the maintenance of minimum plasma concentrations of IS-5MN of 300 ng/ml or higher produces a rapid development of hemodynamic nitrate tolerance, whereas no tolerance was found when the plasma concentrations were allowed to decline below 100 ng/ml before the next dose was given. A significant attenuation of hemodynamic effects was found when minimum plasma concentrations were between 100 and 230 ng/ml. The degree of attenuation in this concentration range increased with increasing trough plasma concentrations.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1041
    Keywords: Key words Digital pulse plethysmography; nitroglycerin ; nifedipine ; left ventricular preload
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: Changes in the contour of the plethysmographically recorded digital pulse curve after nitrate ingestion are well known, but it has not been fully established whether these changes reflect nitrate action on left ventricular (LV) preload or afterload. Therefore, we compared the pulse wave contour after administration of equieffective doses of nitroglycerin and nifedipine. Methods: In 20 patients with coronary artery disease we measured aortic blood pressure curve in the aorta ascendens, digital volume pulse curve with a photoelectric pulse pickup, Riva Rocci blood pressure and heart rate after administration of either 0.8 mg nitroglycerin or 10 mg nifedipine. Results: Peak plasma concentrations of nitroglycerin and nifedipine were achieved 5 min and 20 min after ingestion of the drugs. Systolic aortic blood pressure decreased after both nitroglycerin and nifedipine to 19.4 mmHg, but diastolic blood pressure decreased only after nifedipine by 10.5 mmHg (P 〈 0.05). Riva Rocci blood pressures showed a similar time course. Heart rate increased from 67.4 to 70.9 beats⋅min−1 after nitroglycerin and from 58.9 to 69.4 beats⋅min−1 after nifedipine. The calculated a/b ratio of the aortic pressure curve increased after both medications (nitroglycerin, from 1.66 to 1.99; nifedipine, from 1.66 to 1.93) and its time course mimicked that of the systolic blood pressure. The a/b ratio of the digital pulse curve did not change after nifedipine, but showed a pronounced rise after nitroglycerin from 1.29 to 1.84. With regard to pharmacological actions, nitroglycerin causes a reduction in LV preload and afterload, whereas nifedipine has only LV-afterload-reducing activity. Conclusion: We conclude, that the reduction in afterload did not cause the typical changes in wave contour of the peripheral pulse curve which occur with organic nitrates. Most likely changes in the a/b ratio reflect changes in LV preload.
    Type of Medium: Electronic Resource
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