Treatment of severe hypertension by repeated bolus injections of labetalol.

Abstract

1 Repeated intravenous bolus injections of labetalol were administered to 15 severely hypertensive patients. In 11 instances, a standard protocol was followed in which a loading dose of 1 mg/kg was given intravenously over 1 min, followed by up to five bolus injections of 50 mg at 10-min intervals. In two further patients, bolus doses varying from 25-100 mg were given after the loading dose, and in two others the loading dose was omitted. 2 Falls in systolic BP ranging from 26-194 mmHg were seen in 14 patients and of diastolic BP from 16-76 mmHg in 13. In one patient there was no appreciable fall in either systolic or diastolic BP and in one no marked fall in diastolic BP, although systolic BP dropped by 42 mmHg. 3 The reduction in arterial BP was smooth in ten patients. 4 In four patients a steep fall in BP, of 194 to 101 mmHg systolic, was seen within 10 min of an injection of labetalol; in all four hypotension was readily controlled by elevating the foot of the bed. 5 Side-effects included nausea, vomiting, epigastric discomfort, scalp tingling, burning sensations in the throat and groin, shivering, and pain at the site of injection. Side-effects limited the dose given in four patients. 6 In no case was there clinical or electrocardiographic evidence of myocardial ischaemia induced by labetalol. 7 Labetalol, given by bolus injection, appeared less efficient in controlling arterial pressure, and more likely to cause side-effects, than when given, as in a previous study, by incremental infusion. 8 When labetalol is to be given intravenously for the control of severe hypertension, incremental infusion, rather than bolus injection, is preferred.

Intravenous labetalol in severe hypertension.

“…Labetalol, the combined a-and P-adrenoceptorblocking agent, has been shown to be very effective in the treatment of hypertensive crises when given intravenously (Agabiti-Rosei et al, 1976;Cumming et al, 1979). Compared with other anti-hypertensive drugs used in these situations, it has the advantage that treatment can be continued with the oral preparation.…”

Labetalol, an alpha‐ and beta‐adrenoceptor‐blocking agent: its use in therapeutics. A summary of the symposium.

“…This is possibly a function of the initial effects of a lowering of the BP and diminution of side-effects with time as has been reported, regardless of the drug administered when bethanidine, guanethidine and methyldopa were examined (Prichard et al, 1968). When large doses are given intravenously a number of side-effectsnausea, vomiting, epigastric discomfort and scalp tingling may occur (Cumming et al, 1979b). Transient tiredness in three patients, and transient calf muscle pain in two patients were reported in a series of 17 patients by Andersson et al (1976).…”

“…After continuous oral administration to patients, small reductions in resting heart rate are usually recorded (Lund-Johansen, 1979;New Zealand Hypertension Study Group, 1979), although individual changes are influenced by the degree of resting sympathetic drive. In those patients with high resting heart rates and therefore high sympathetic drive, more marked reductions in resting heart rate are seen after labetalol, particularly after intravenous administration (Cumming et al, 1979b;Marx & Reid, 1979).…”

“…Onset of action and therapeutic potency Labetalol after acute intravenous (Cumming et al, 1979b) and acute oral administration (Ghose, 1979;Thompson et al, 1979) at rest and during exercise (Balasubramanian et al, 1979a) reduces BP in hypertensive patients. This immediate hypotensive effect of the drug distinguishes it from fi-adrenergic blocking drugs that do not possess cx-blocking activity (Prichard, 1978) and is likely to have resulted predominantly from its a-blocking component, although in long-term oral treatment its combined aand fl-blocking properties were undoubtedly responsible for the maintained control of BP in hypertensive patients.…”

Advances in pharmacotherapy: Treatment of hypertensive crisis

“…Trials investigating intravenous labetalol have studied various dosage regimens which include: (I) a bolus dose followed by a continuous infusion (60); (2) a constant infusion without a bolus dose (66,71); (3) a single large bolus dose (71); and (4) repeated bolus injections (64,65,71,72). Overall, each of the regimens provides effective BP control.…”