Biomedical subjects

G Johnsson

Publications and source records attributed to G Johnsson.

At least 55 records · Page 3Linked to original sources

PubMed1975

Effects of intravenous propranolol and metoprolol and their interaction with isoprenaline on pulmonary function, heart rate and blood pressure in asthmatics.

The effects of propranolol (0.06 mg/kg i.v.), the selective beta1-receptor antagonist metoprolol (0.12 mg/kg i.v.) and a placebo on pulmonary function, heart rate and blood pressure have been compared in asthmatics. The interaction of these drugs with increasing doses of isoprenaline on the same variables was also studied. The two beta-blockers reduced resting heart rate to the same extent, indicating the same degree of blockade of cardiac beta-receptors. Both beta-blockers reduced the basal forced expiratory volume in one second (FEV1), and the effect tended to be more pronounced after propranolol. Isoprenaline caused a dose-dependent increase in FEV1 and vital capacity (VC). These effects were almost completely blocked by propranolol, whereas after metoprolol the changes approached that of the placebo. The isoprenaline-induced increase in heart rate and fall in diastolic blood pressure was also inhibited to a considerably greater extent by propranolol than by metoprolol. The results show a selectivity of metoprolol for so-called beta1-receptors and indicate that metoprolol may be used in asthmatics provided that it is combined with beta2-receptor-stimulating drugs.

Adult↗

PubMed1975

Effects of metoprolol and propranolol on furosemide-stimulated renin release in healthy subjects.

The effects of single doses of the beta1-receptor antagonist metoprolol (40 mg orally), propranolol (40 mg orally) and placebo were compared on furosemide-stimulated plasma renin activity (PRA) in seven healthy subjects. In the placebo studies, PRA increased by 0.59+/-0.18 ng x ml-1 x h-1 60 minutes after intravenous administration of 30-60 mg furosemide. After propranolol and metoprolol, the corresponding increases in PRA were significantly less pronounced amounting to 0.16+/-0.06 and 0.24+/-0.08 ng x ml-1 x h-1, respectively. The resting heart rate was reduced to the same extent after the two beta-blockers, which means that the two drugs had been given in equipotent beta1-receptor blocking doses. It is suggested that the release of renin from the kidney may partly be mediated via an adrenergic beta1-receptor.

Adult↗

PubMed1975

Effect of different doses of chlorthalidone on blood pressure, serum potassium, and serum urate.

Chlorthalidone given to 40 hypertensive women significantly decreased blood pressure and serum potassium levels and increased the serum urate concentration. There were no individual correlations between the reduction in blood pressure and the decrease in serum potassium or the increase in serum urate. A reduction in dosage from 50 mg daily to 50 mg three times a week produced no significant changes in the diastolic or mean blood pressures though the systolic blood pressure was moderately increased. Concomitantly, serum potassium increased and serum urate decreased significantly on the lower chlorthalidone dose. We conclude that high doses of oral diuretics compared with lower ones are of limited further benefit and may increase the risk of clinically significant hypokalaemia and hyperuricaemia.

Blood Pressure↗

PubMed1975

Plasma levels and effects of metoprolol on blood pressure and heart rate in hypertensive patients after an acute dose and between two doses during long-term treatment.

Plasma levels and the effect of orally administered metoprolol on the resting arterial blood pressure and heart rate have been studied during acute and steady-state conditions in patients with mild hypertension. The patients receiving an 80-mg dose had a mean maximum plasma level of about 100 ng/ml plasma in single-dose studies and about 140 ng/ml plasma during steady-state conditions. The corresponding values for the patients on the 50-mg dose were about 60 and 100 ng/ml plasma, respectively. The maximum concentrations were reached 1 hr after administration. After the single dose the elimination half-life of metoprolol in plasma was 4.3 plus or minus 0.7 hr in the patients receiving the 80-mg dose and 3.8 plus or minus 0.3 hr in the other group. The difference was not statistically significant. The elimination half-life in the plasma was about the same in the single-dose study and during steady state in both groups. The morning dose induced a decrease of the systolic blood pressure whereas the diastolic blood pressure was not significantly different from that recorded immediately before administration of metoprolol. For the 80-mg dose the systolic pressure dropped from 167 plus or minus 4 to 146 plus or minus 4 mm Hg in the single dose study and from 160 plus or minus 8 to 140 plus or minus 4 mm Hg at steady state. The corresponding values for the 50-mg dose were 150 plus or minus 3 to 135 plus or minus 3 mm Hg and 144 plus or minus 3 to 138 plus or minus 3 mm Hg, respectively. In experiments with placebo the systolic blood pressure was not significantly changed. There was no correlation between the plasma levels and the effect on the systolic blood pressure. Both doses of metoprolol markedly reduced the heart rate after the single dose as well as at steady state. The effect was linearly related to the logarithm of the plasma concentration, and the relationship was virtually the same as obtained previously for the effect on exercise heart rate in healthy volunteers.

Adrenergic beta-Antagonists↗

PubMed1975

Pharmacokinetics of procainamide intravenously and orally as conventional and slow-release tablets.

Pharmacokinetics of procainamide were studied in healthy volunteers after single doses intravenously and orally as conventional and slow-release tablets and after repeated oral doses to steady state. The initial distribution after intravenous administration was rapid and the overall elimination in the beta-phase corresponded to t1/2 of 2.7 hr. The mean volume of the central compartment was small and only 4 percent of V-d (beta), which was 2.3 l/kg body weight. About 65 percent was excreted unchanged after intravenous administration and about 55 percent after a single oral dose of 500 mg. The recovery of the metabolite N-acetylprocainamide was 12 percent after both routes of administration. Procainamide was completely absorbed from the gastrointestinal tract and the first-pass elimination was very limited. The rates of absorption from the tablet compositions were well correlated to the in vitro dissolution properties. Administration of slow-release tablets every 8 hr gave about the same mean plasma level at steady state as ordinary tablets given every 4 hr, and the availability was the same from both preparations. The occasional high plasma concentration peaks after ordinary tablets were not observed after the slow-release tablets. Renal clearance was about 500 ml/min, indicating an active secretion in the tubules.

Acetylation↗

PubMed1975