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Biomedical subjects

K Balnave

Publications and source records attributed to K Balnave.

10 recordsLinked to original sources
PubMed1988

Streptokinase and reduced plasma viscosity: a second benefit.

The purpose of this pilot study on a small cohort of patients (n = 13) with acute myocardial infarction receiving systemic streptokinase (STK) thrombolytic therapy was to measure the decrease in plasma viscosity concomitant with fibrinogen depletion. The treatment group was compared with a similar control group not given thrombolytic therapy. Serial relevant blood studies were undertaken in both groups for a period of 6 d. In the treatment group, a maximum reduction in plasma viscosity of 17 +/- 9% (mean +/- S.D.) was achieved during the first 24 h. Plasma viscosity remained below baseline for the 6-d duration of the study. Conversely, in the control group, the plasma viscosity rose to a maximum of 19 +/- 14% (mean +/- S.D.) over the period of study, paralleling the rise in plasma fibrinogen as an acute-phase reactant. Correlation studies between viscosity and plasma fibrinogen were strongly positive with mean values of r of 0.74 and 0.66 in the STK-treated group and controls, respectively. We conclude that the benefit of systemic STK treatment may in part be due to reduced myocardial workload and oxygen consumption at a critical time, and improved microvascular circulation, consequent on reduced plasma viscosity.

Blood Cell Count↗
PubMed1984

The effects of cyclosidimine, a peripheral vasodilator drug, on blood pressure and heart rate in healthy subjects.

Cyclosidimine is a new vasodilator drug with a direct action on vascular smooth muscle. Oral administration of 2.5, 5.0 and 7.5 mg in five normal volunteers had no effect on blood pressure in the supine position but reduced systolic and diastolic pressure in the erect position. In both positions heart rate was significantly greater after cyclosidimine than after placebo. Propranolol prevented the increases in heart rate produced by cyclosidimine which then produced greater reductions in blood pressure.

Adult↗
PubMed1981

Effects on exercise tachycardia during forty-eight hours of a series of doses of atenolol, sotalol, and metoprolol.

Beta adrenoceptor blockers differ mainly in their plasma elimination half-lives (t 1/2 s). It has been assumed that drugs with longer t 1/2 will have a longer duration of effect on exercise tachycardia. Several factors may influence the duration of action of beta blockers; we have investigated the contribution of plasma elimination t 1/2 and dose by comparing the effects on an exercise tachycardia in healthy subjects of placebo, 25, 50, 100, and 200 mg of atenolol and of sotalol, and 50, 100, 200, and 400 mg metoprolol. Subjects exercised before and at 2, 3, 6, 8, 24, 33, and 48 hr after oral doses of each drug. Plasma samples for measurement of drug concentration were drawn before each exercise period. Twenty-four hours after 50, 100, and 200 mg atenolol and 50, 100, 200, and 400 mg sotalol there were reductions in an exercise tachycardia; at this time reductions were greater after the larger doses. The plasma elimination t 1/2s of atenolol were between 7.2 +/0 1.0 hr. Although 50, 100, and 200 mg metoprolol induced the same reductions in an exercise tachycardia 2 hr after drug as 25, 50, and 100 mg atenolol and 50, 100, and 200 mg sotalol, these doses were without effect at 24 hr. Metoprolol 400 mg reduced exercise tachycardia at 24 hr but the effect was less than that of the three largest doses of atenolol and sotalol. The plasma elimination t 1/2 for metoprolol was between 3.6 +/- 0.6 and 5.0 +/- 1.8 hr. These results show that duration of cardiac beta blocking of cardiac beta blocking activity of atenolol, sotalol, and metoprolol is determined by the elimination t 1/2 and dose.

Adolescent↗
PubMed1981

Observation on the efficacy and pharmacokinetics of betaxolol (SL 75212), a cardioselective beta-adrenoceptor blocking drug.

1 Observations were made in five subjects who exercised before and at 2, 3, 6, 8, 24, 33 and 48 h after the oral administration of placebo and 5, 10, 20 and 40 mg betaxolol. 2 The exercise heart rate remained constant at all times after the placebo. All doses of betaxolol significantly reduced the exercise tachycardia at all times. The maximum effect (34.4 +/- 2.2%) occurred after 40 mg. 3 There was a small decline in effect from the peak to 24 h when 40 mg produced a 23.3 +/- 2.7% reduction and a further decline to 48 h when there was a 14.6 +/- 1.8% reduction. 4 Plasma levels of betaxolol were measured in these studies. The peak plasma concentration occurred between 3 and 8 h with different doses. The plasma elimination half-lives after 10, 20 and 40 mg were 11.4 +/- 2.5, 15.9 +/- 4.9 and 15.1 +/- 3.1 h. 5 The effects of 40 mg betaxolol, 200 mg atenolol, 160 mg propranolol, 160 mg oxprenolol, 400 mg sotalol and placebo on an exercise tachycardia were compared in five subjects who received all treatments in random order. 6 There was no significant difference in the maximum reduction produced in an exercise tachycardia by the different drugs. 7 The effect of all drugs decreased with time. The effect of oxprenolol had worn off at 24 h but at 48 h only atenolol and betaxolol produced significant reductions in the exercise tachycardia. 8 Plasma concentrations of the different drugs were measured and plasma elimination half-lives determined. The half-life for betaxolol was 24.5 h which was longer than that for any of the other drugs. 9 These observations show that betaxolol is a potent beta-adrenoceptor antagonist with a long duration of effect on an exercise tachycardia and a long plasma elimination half-life.

Adrenergic beta-Antagonists↗
PubMed1980

Comparison of propranolol and inderal L.A. in patients with angina.

TWELVE patients with moderately severe angina pectoris completed a double blind cross-over comparison of conventional propranolol (40 mg q.i.d.) and Inderal L.A. (160 mg once daily) with regard to therapeutic effectiveness, blood levels, compliance and patient acceptability.Exercise tolerance was assessed using standardised treadmill testing at 1, 2, 4, 8, 12 and 24 hours after the morning dose. The double placebo technique was used.Patient compliance was excellent for both regimes and no serious side effects were reported. No significant differences in exercise tolerance or blood levels were observed between the two treatments at any time.

Aged↗