A long-term study of labetalol in general practice

Intravenous labetalol in the management of resistant hypertensive emergency

A case of intravenous labetalol in the treatment of a resistant hypertensive emergency is reported. Although there have been several reports of the use of oral labetalol in resistant hypertension, no intravenous administration in hypertensive emergency resistant to other drugs has been reported to date. A 36-year-old black female with BP of 270/160 mm Hg with complaints greater than one month's duration of dizziness, severe headaches, blurred vision, shortness of breath, vomiting, palpitations, flushing, agitation, diarrhea, weakness, and weight loss, was treated successfully with intravenous labetalol after she failed to respond to other established parenteral antihypertensive drugs. The patient received labetalol 20 mg iv bolus, and then 20 mg every ten minutes until a cumulative dose of 200 mg was attained. Labetalol produced a prompt but smooth reduction in BP without any reflex tachycardia or other adverse effects. Intravenous labetalol may be safe and effective for the management of rapid BP control in hypertensive emergencies resistant to other parenteral antihypertensive agents.

A comparison of labetalol and prazosin combined with atenolol in non-responders to atenolol plus hydrochlorothiazide in uncomplicated hypertension

After screening two local populations in the northern part of The Netherlands for hypertension, patients with a diastolic pressure (DP) between 95 and 120 mmHg were treated daily either with 50 mg hydrochlorothiazide or 100 mg atenolol. Nonresponders were given the combination and if necessary the dose of atenolol was increased to 200 mg. Non-responders to the latter combination were randomized and treated either with 50 mg hydrochlorothiazide and labetalol or with 50 mg hydrochlorothiazide, 200 mg atenolol and prazosin. If after 1 month a DP less than or equal to 90 mmHg had been reached the patient was reassessed after a further 3 months. If a DP greater than 90 mmHg was found the dose of labetalol or prazosin was increased and the patient was re-examined after 1 month. This protocol was followed until the maximum dose was reached or adverse reactions prevented a further increase in dosage. During 6 months of treatment there was a further drop in systolic and diastolic blood pressures under both regimens of, respectively, 8.6 and 2.4 mmHg for labetalol, and 7.7 and 5.0 mmHg for the prazosin group. At the end of the period the average daily doses of labetalol and prazosin were 1256 mg and 4.3 mg, respectively. There was no significant difference in the average number of complaints between the labetalol and the prazosin group.

Antihypertensive effectiveness of intravenous labetalol in accelerated hypertension

Labetalol, an antihypertensive agent that blocks both beta- and alpha-adrenergic receptors, was administered intravenously to 19 patients with accelerated hypertension who required rapid lowering of blood pressure. Systolic blood pressure was lowered from 209 +/- 4 to 143 +/- 2 mm Hg; diastolic blood pressure was reduced from 140 +/- 2 to 93 +/- 2 mm Hg. Side-effects were minimal and included nausea, epigastric burning, rhinorrhea, and premature ventricular contractions. One patient became hypotensive and required treatment. Overall, the study demonstrates labetalol to be a safe and effective agent for the emergency lowering of blood pressure, with demonstrated results comparable to other parenteral agents.

Labetalol in general practice: a review

1 The results of the treatment of 8573 hypertensive patients with labetalol in general practice, for periods between 1 month and 5 yr, are reviewed. 2 The data reviewed were obtained from the published literature together with our own published (Kane et al., 1976; Kane et al., 1979) and more recent (unpublished) work. 3 Between 60% and 80% of severe (diastolic blood pressure greater than 120 mmHg) and previously uncontrolled hypertensives responded satisfactorily to the drug, as did up to 88% of mild to moderate hypertensives. 4 The anti-hypertensive effect of labetalol was not dependent on the frequency of administration, twice and three times daily treatment regimes being equally effective. 5 The withdrawal rate attributable to side-effects was between 6% and 13%. Tiredness, dizziness, headache and upper gastro-intestinal symptoms were the four principal side-effects, but they were usually transient when labetalol treatment was continued. 6 No drug interactions or adverse haematological or biochemical changes were seen.

Blood pressure, body fluid volumes and glomerular filtration rate during treatment with labetalol in essential hypertension

1 In a single blind study seventeen patients with mild or moderate essential hypertension and normal renal function were treated with labetalol alone in increasing doses from 300 via 600 to 1200 mg daily. 2 Average supine BP (systolic/diastolic) was reduced by 24/19 mm Hg. Seven patients attained a diastolic BP less than or equal to Hg. A significant postural fall in systolic BP was recorded, but no symptomatic orthostatic hypotension occurred. 3 In twelve patients measurements of plasma volume (125I-albumin), extracellular volume (82Br-space) and glomerular filtration rate (51Cr-EDTA clearance) on placebo and subsequently labetalol showed no systemic changes. 4 Side effects were few causing two withdrawals because of impotence and arthralgia. 5 It is concluded that monotherapy with labetalol results in clinically relevant, persistent and dose dependent reduction in BP in patients with mild or moderate essential hypertension, apparently without concomitant expansion of body fluid volumes or influence on glomerular filtration rate.