Some further evidence for partial agonist activity of labetalol.

Aj, Riley

doi:10.1111/j.1365-2125.1980.tb05849.x

Cited by 18 publications

(6 citation statements)

References 2 publications

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“…This would be consistent with the findings of MacLennan et al [4]. Labetalol 200 mg also had a trend to increase finger tremor which is suggestive of 132-adrenoceptor agonist activity which has also been suggested by other investigators who found a rise in plasma glucose following treatment with labetalol [18]. However, further studies would be required to confirm this.…”

Section: Discussionsupporting

confidence: 91%

The dose dependency of the alpha‐adrenoceptor antagonist and beta‐ adrenoceptor partial agonist activity of dilevalol and labetalol in man.

Tham¹,

McKaigue²,

Guy³

et al. 1993

Brit J Clinical Pharma

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1 The a-adrenoceptor antagonist, P,-adrenoceptor antagonist and ,82-partial agonist activity of dilevalol, a ,3-adrenoceptor antagonist with vasodilating properties and labetalol were investigated in two studies. 2 In the first study, six healthy male subjects received serially increasing concentrations phenylephrine after single oral doses of dilevalol 200 mg, labetalol 400 mg and placebo at weekly intervals in a randomised double-blind manner. An exercise step test was performed at the end of the infusions. 3 The doses of phenylephrine required to increase systolic and diastolic blood pressures by 20 mmHg (PS20 and PD20 respectively) were increased by labetalol 400 mg (P < 0.05) but unchanged by dilevalol 200 mg. The dose ratios for PS20 (means ± s.d.)were: dilevalol 200 mg 1.1 ± 0.1, labetalol 400 mg 2.2 ± 0.1. There was no difference in the percentage reduction in exercise tachycardia between dilevalol and labetalol. 4 In the second study, 10 healthy male subjects received infusions with serially increasing concentrations of phenylephrine and angiotensin II before and after single oral doses of dilevalol 200, 400 and 800 mg, labetalol 200 mg and placebo at weekly intervals in a double-blind randomised manner. Finger tremor was measured (piezoelectric accelerometer) with each infusion. An exercise step test was performed at the end of the infusions. 5 The PS20 and PD20 of phenylephrine were increased by labetalol 200 mg and unchanged by dilevalol. The dose ratios for PS20 were: dilevalol 200 mg 1.1 ± 0.2, dilevalol 400 mg 1.1 ± 0.4, dilevalol 800 mg 1.4 ± 0.4 and labetalol 200 mg 2.5 ± 0.7. The dose ratios for PD20 were: dilevalol 200 mg 1.1 ± 0.4, dilevalol 400 mg 0.9 ± 0.3, dilevalol 800 mg 1.3 ± 0.4 and labetalol 200 mg 2.3 ± 0.9. 6 The PS20 and PD20 of angiotensin II were unchanged by any of the drugs. 7 Exercise heart rate was reduced by dilevalol 200 mg (130 ± 13 beats min-1), 400 mg (123 ± 12 beats min-1), 800 mg (125 ± 9 beats min) and labetalol 200 mg (143 ± 12 beats min-1) vs placebo (161 ± 17 beats min-').

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Section: Discussionsupporting

confidence: 91%

The dose dependency of the alpha‐adrenoceptor antagonist and beta‐ adrenoceptor partial agonist activity of dilevalol and labetalol in man.

Tham¹,

McKaigue²,

Guy³

et al. 1993

Brit J Clinical Pharma

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“…However, its effects on glycaemic control in diabetic subjects have never been formally assessed. All that can be said is that hydralazine does not affect glucose tolerance in normal subjects (Riley, 1980).…”

Section: Vasodilatorsmentioning

confidence: 99%

The choice of antihypertensive therapy in the diabetic patient

Struthers

1985

Postgraduate Medical Journal

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“…On the other hand plasma cyclic AMP increased after labetalol which may be explained by partial ,3-adrenoceptor agonist activity of the compound (Carey & Whalley, 1979;Riley, 1980) or by active metabolites of labetalol. The presence of such metabolites is also suggested by the poor correlation between plasma concentrations of labetalol and the hypotensive effect (McNeil et al, 1979) and perhaps by our chromatographic findings.…”

Section: Discussionmentioning

confidence: 99%

“…The possibility therefore exists that combined a-and ,3-adrenoceptor blockade may be especially useful in the treatment of pregnancy hypertension. Labetalol is an effective antihypertensive drug (Prichard et al, 1975;Bolli et al, 1977) which combines a-and 8-adrenoceptor blocking properties (Richards & Prichard, 1979) and also appears to possess f3-adrenoceptor agonist activity (Carey & Whalley, 1979;Riley, 1980).…”

Section: Introductionmentioning

confidence: 99%

Circulatory and metabolic effects of a combined alpha‐ and beta‐ adrenoceptor blocker (labetalol) in hypertension of pregnancy.

Lunell¹,

Hjemdahl²,

Bb³

et al. 1981

Brit J Clinical Pharma

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1 Seven women with hypertension of pregnancy were given the combined a-and ,8-adrenoceptor blocking drug labetalol (50 mg i.v.) in their last trimester. Acute effects were studied for 3 h after administration. 2 Systolic and diastolic blood pressures were significantly reduced from 143 ± 4 (s.e. mean) to 127 ± 5 mmHg and from 101 + 2 to 88 + 2 mmHg, respectively. Maternal heart rate fell significantly from 77 + 5 to 68 + 3 beats/min. The changes remained during the 3 h of observation. Foetal heart rate was not affected. No side-effects were encountered. 3 Plasma noradrenaline increased significantly from 1.54 + 0.16 to a peak value of 2.37 + 0.41 nmol/l suggesting sympathetic activation following labetalol. Plasma adrenaline levels were essentially unchanged. Plasma glucose, insulin and C-peptide showed only minor changes. No major effects on lipid metabolism were seen except a significant fall of nonesterified fatty acids at 60 min. Plasma cyclic AMP increased significantly throughout the observation period, perhaps indicating f-adrenoceptor agonist activity of labetalol. 4 The effectiveness of labetalol as an acute hypertensive agent together with apparent absence of metabolic disturbances and other side-effects makes it an interesting drug for the treatment of hypertension during pregnancy.

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Some further evidence for partial agonist activity of labetalol.

Cited by 18 publications

References 2 publications

The dose dependency of the alpha‐adrenoceptor antagonist and beta‐ adrenoceptor partial agonist activity of dilevalol and labetalol in man.

The dose dependency of the alpha‐adrenoceptor antagonist and beta‐ adrenoceptor partial agonist activity of dilevalol and labetalol in man.

The choice of antihypertensive therapy in the diabetic patient

Circulatory and metabolic effects of a combined alpha‐ and beta‐ adrenoceptor blocker (labetalol) in hypertension of pregnancy.

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