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Query: UMLS:C0085580 (essential hypertension)
 14,686 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Labetalol is a combined alpha- and beta-adrenoceptor blocking agent for oral and intravenous use in the treatment of hypertension. It is a nonselective antagonist at beta-adrenoceptors and a competitive antagonist of postsynaptic alpha 1-adrenoceptors. Labetalol is more potent at beta that at alpha 1 adrenoceptors in man; the ratio of beta-alpha antagonism is 3:1 after oral and 6.9:1 after intravenous administration. Labetalol is readily absorbed in man after oral administration, but the drug, which is lipid soluble, undergoes considerable hepatic first-pass metabolism and has an absolute bioavailability of approximately 25%. There are no active metabolites, and the elimination half-life of the drug is approximately 6 hours. Unlike conventional beta-adrenoceptor blocking drugs without intrinsic sympathomimetic activity, labetalol, when given acutely, produces a decrease in peripheral vascular resistance and blood pressure with little alteration in heart rate or cardiac output. However, like conventional beta-blockers, labetalol may influence the renin-angiotensin-aldosterone system and respiratory function. Clinical studies have shown that the antihypertensive efficacy of labetalol is superior to placebo and to diuretic therapy and is at least comparable to that of conventional beta-blockers, methyldopa, clonidine and various adrenergic neuronal blockers. Labetalol administered alone or with a diuretic is often effective when other antihypertensive regimens have failed. Studies have shown that labetalol is effective in the treatment of essential hypertension, renal hypertension, pheochromocytoma, pregnancy hypertension and hypertensive emergencies. In addition, preliminary studies indicate that labetalol may be of value in the management of ischemic heart disease. The most troublesome side effect of labetalol therapy is posture-related dizziness. Other reported side effects of the drug include gastrointestinal disturbances, tiredness, headache, scalp tingling, skin rashes, urinary retention and impotence. Side effects related to the beta-adrenoceptor blocking effect of labetalol, including asthma, heart failure and Raynaud's phenomenon, have been reported in rare instances.
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PMID:Labetalol: a review of its pharmacology, pharmacokinetics, clinical uses and adverse effects. 631 May 29

Thirteen patients with mild essential hypertension, mean age 44 years (range 21-59), were studied during "stress" before and after postsynaptic alpha-adrenoceptor blockade and combined postsynaptic alpha- and non-selective beta-adrenoceptor blockade. Loud broad band noise (100 dBA for 10 min) was used as the stress stimulus. Exposure to noise caused a significant increase in systolic (7%, p less than 0.05), diastolic (9%, p less than 0.01) and mean arterial pressure (6%, p less than 0.01). The blood pressure elevation was caused by an increase in total peripheral resistance (12%, p less than 0.05). There was no significant change in heart rate, stroke volume or cardiac output. The blood pressure response during noise stimulation was not affected by postsynaptic alpha-adrenoceptor blockade (prazosin, 2 mg orally). The hemodynamic reaction pattern, however, was totally reversed. Thus, the cardiac output increased significantly (9%, p less than 0.05), while the total peripheral resistance tended to decrease. Combined postsynaptic alpha- and non-selective beta-adrenoceptor blockade (labetalol, 200 mg orally) inhibited the increase in systolic blood pressure caused by noise, while the diastolic and mean arterial pressures still increased significantly (5%, p less than 0.01). Labetalol effectively blocked the stress-induced increase in total peripheral resistance and there was no significant increase in cardiac output after combined alpha- and beta-adrenoceptor blockade. Exposure to noise caused a significant increase in circulating noradrenaline (20%, p less than 0.05). Plasma adrenaline and plasma renin activity were not affected by noise stimulation. These results suggest that blood pressure elevation is essential during "stress" but that the hemodynamic pattern causing blood pressure elevation may vary and may be affected by pharmacological blockade of various parts of the sympathetic nervous system.
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PMID:Circulatory effects of noise. 633 82

Labetalol, a new alpha- and beta-adrenergic blocking agent, was administered to 57 patients with essential hypertension whose standing diastolic blood pressure was 105 to 120 mm Hg after three and four weeks of placebo therapy and greater than 90 mm Hg after three to four weeks of therapy with hydrochlorothiazide, 25 mg twice a day. Patients were then randomly assigned on a double-blind basis to receive either labetalol, 100 mg twice a day, or placebo combined with hydrochlorothiazide. Thereafter, the dose of labetalol was titrated weekly in both groups to a maximum of 400 mg twice a day to achieve a standing diastolic blood pressure of less than 90 mm Hg that was also decreased from the hydrochlorothiazide baseline by 10 mm Hg or more (therapeutic goal). Labetalol was abruptly discontinued after four weeks of treatment and patients were given hydrochlorothiazide alone for two additional weeks. After one week of labetalol therapy, 100 mg twice a day (added to hydrochlorothiazide), there was a significantly greater reduction in supine systolic/diastolic blood pressure (6/5 mm Hg, p less than 0.04/less than 0.03) and standing blood pressure (9/7 mm Hg, p less than 0.01/less than 0.01) than with placebo therapy (3/0.5 and 3/1 mm Hg, respectively). The blood pressure reduction in the labetalol-treated group was associated with a 4 and 5 beats per minute reduction in the supine and standing heart rates, respectively. The median labetalol dose required to achieve the standing diastolic blood pressure goal was 400 mg twice a day. After four weeks of labetalol treatment, the mean reduction in blood pressure from the hydrochlorothiazide baseline was 12/13 mm Hg (p less than 0.01/0.01) in the standing position and 8/8 mm Hg (p less than 0.01/0.01) in the supine position. These blood pressure reductions were accompanied by a mean reduction in heart rate of 7 beats per minute. The most frequently reported complaints other than thiazide-induced nocturia included dizziness, fatigue, nausea, rash, and/or pruritus. Most of these complaints were reported at a similar incidence while patients were receiving placebo or hydrochlorothiazide alone as when receiving labetalol with hydrochlorothiazide. After abrupt withdrawal of labetalol, no evidence of rebound hypertension was observed. Labetalol is a safe and effective step II drug when added to hydrochlorothiazide for the treatment of patients with moderate to moderately severe hypertension.
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PMID:Step II treatment with labetalol for essential hypertension. 635 2

Thirty-two patients with primary hypertension were studied in a double-blind cross-over comparison between the cardioselective beta 1-blocking agent atenolol and the combined alpha- and beta-blocking agent labetalol. The doses used were atenolol 50--150 mg twice daily and labetalol 200--600 mg twice daily. Both drugs effectively reduced blood pressure and heart rate. Dose increments every second week resulted in a higher proportion of patients with normal blood pressure (les than or equal to 150/90 mm Hg) with both drugs. Labetalol was somewhat more effective in lowering upright blood pressure while atenolol caused a more pronounced heart-rate reduction. Both agents decreased plasma renin activity and urinary aldosterone excretion. Scalp tingling on labetalol (2 patients) and cold fingers with atenolol (1 patient) caused withdrawal of the drugs. Cold fingers were reported in another four patients during treatment with atenolol and in one when on labetalol. Tiredness and postural symptoms were more common during intake of labetalol.
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PMID:Antihypertensive and metabolic effects of increasing doses of atenolol and labetalol. A comparative study in primary hypertension. 676 Jun 79

Labetalol has been successful in treating hypertension, and few side effects have been reported, although there have been cases of muscle pain during treatment. A patient with essential hypertension treated with labetalol 600 mg daily complained of muscle pains, particularly in the legs. No neurological abnormality was found, but the activity of muscle enzymes in the blood was high. Findings on electromyography were compatible with myositis and electron microscopical findings suggested toxic myopathy. Labetalol was stopped for 10 days, and the muscle pain disappeared and enzyme activity returned to normal. When labetalol was restarted the pain returned and enzyme activities rose. Myopathy should be considered in patients experiencing muscle pain after treatment with labetalol.
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PMID:Labetalol-induced toxic myopathy. 678 36

Labetalol inhibits alpha- and beta-adrenergic receptors. Systemic and regional hemodynamic alterations after intravenous labetalol and its cardiovascular reflexive and metabolic effects were evaluated in 12 subjects with mild to moderately severe essential hypertension. Supine systolic, diastolic, and mean pressures were reduced (from 180/101 and 125 to 149/86 and 109 mm Hg; P less than 0.001). The fall was accentuated during head-up tilt and was accompanied by decreased cardiac output and central blood volume in subjects in both the supine and tilted positions. Neither heart rate nor total peripheral resistance was changed by labetalol, suggesting that venodilation resulting from alpha-adrenergic-receptor inhibition played an important role in arterial pressure reduction.
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PMID:Hemodynamic effects of intravenous labetalol in essential hypertension. 682 26

1 Labetalol has been compared with propranolol in a double-blind, double-dummy study of 24 patients with mild or moderate essential hypertension. 2 Two patients were unable to tolerate propranolol and five labetalol, because of symptom side effects; this difference was not significant (P greater than 0.1). 3 On a self-administered questionnaire, labetalol was associated with a greater number of side effects per patient than propranolol, but no individual side effect was significantly more common with either drug. 4 There was no difference in the number of spontaneously reported side effects between the two drugs. 5 Both drugs impaired pulmonary function, but propranolol caused a greater reduction than labetalol after 8 weeks of treatment. 6 We conclude that labetalol and propranolol are similarly effective and acceptable to the patient.
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PMID:Comparison of labetalol and propranolol in hypertension. 698 3

1 Labetalol, an alpha- and beta- adrenoceptor blocking drug, was compared with acebutolol, alone or associated with dihydralazine in forty patients with moderate essential hypertension. 2 Labetalol (400--800 mg daily) seemed to have a slightly higher potency than acebutolol alone (400--800 mg daily). 3 Labetalol (1200--1600 mg daily) had the same potency as the combination of acebutolol (400--800 mg daily) and dihydralazine (50--100 mg daily). 4 Contrarily to acebutolol, the drop in blood pressure with labetalol was not correlated with initial plasma renin activity. 5 Labetalol side effects were minor and did not lead to drug withdrawal.
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PMID:Comparative trial of labetalol and acebutolol, alone or associated with dihydralazine, in treatment of essential hypertension. 699 23

The clinical effects, the exercise test answer, the left ventricular function by polygraphyc test after administration at middle term of Metoprolol and Labetalol have been evaluated in 20 patients with moderate and non complicated essential hypertension. The study was a double blind cross-over between Metoprolol and Labetalol (270 mg/die per os). Both drugs induced a reduction of PAOS and PAOD. The exercise test induced in all patients a decrease of PAOS and PAOD, showing an improvement of strain tolerance. The normalization of PEP and non modification of LVET seem to confirm that the treatment with Metoprolol and with Labetalol, neither induces significant modification of left ventricular function.
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PMID:[Clinical, ergometric and polygraphic evaluation of the effects of metoprolol and labetalol administration in essential arterial hypertension. Comparative study]. 707 Jun 96

1 The anti-hypertensive effect of labetalol given twice or three times daily was evaluated in ambulant subjects with essential hypertension by recording blood pressure directly for 24 h before and after 15 d of labetalol administration (daily dose 600-1800 mg). 2 Labetalol reduced 24 h systolic and diastolic blood pressures by about 20%. The reduction was evident throughout the whole 24 h period, although it was less marked during sleep. The hypotensive effect was similar when the drug was given twice or three times daily. 3 The 24 h heart rate was reduced during labetalol treatment. However, this effect was less marked than the hypotensive effect and was not present in all subjects. 4 There was a reduction in the standard deviations of blood pressure and heart rate values. However, in neither case was the coefficient of variation altered, indicating that labetalol did not have any significant effect on the shape of the 24 h blood pressure measurements.
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PMID:Blood pressure response to labetalol in twice and three times daily administration during a 24-hour period. 709


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