LABETALOL

​

Labetalol is a non-selective beta-adrenergic antagonist (beta-blocker) and a selective alpha-1 adrenergic antagonist. Its unique dual-blocking properties make it particularly useful in the context of anesthesia. The importance of labetalol in anesthesia can be highlighted by the following factors:

​

1. Control of hemodynamic response: Labetalol is used to manage the hemodynamic response to endotracheal intubation, surgical stimulation, or extubation, which can cause a transient increase in heart rate and blood pressure. By blocking both beta and alpha-1 adrenergic receptors, labetalol helps to maintain hemodynamic stability during the perioperative period.

2. Management of intraoperative hypertension: Labetalol can be used to treat intraoperative hypertension, particularly in patients with pre-existing hypertension or when sudden increases in blood pressure occur during surgery. Its combined alpha- and beta-blocking properties help to reduce both the heart rate and vascular resistance, leading to a decrease in blood pressure.

3. Control of heart rate: Labetalol is effective in controlling heart rate during surgery, which is particularly useful in cases where a lower heart rate is desired, such as during vascular, neurosurgical, or ophthalmologic procedures. It may also be used to manage intraoperative arrhythmias, such as atrial fibrillation or supraventricular tachycardia.

​​

Its mechanism of action can be summarized as follows:

​

1. Beta-adrenergic antagonism: Labetalol non-selectively blocks beta-1 and beta-2 adrenergic receptors. By inhibiting beta-1 receptors in the heart, it reduces the effects of catecholamines like norepinephrine and epinephrine. This leads to a decrease in heart rate (negative chronotropic effect), a decrease in the force of cardiac contractions (negative inotropic effect), and a decrease in cardiac conduction velocity. These combined effects help to reduce myocardial oxygen demand and can contribute to controlling heart rate and blood pressure.

2. Alpha-1 adrenergic antagonism: Labetalol also selectively blocks alpha-1 adrenergic receptors, which are primarily found in the smooth muscle of blood vessels. By blocking these receptors, labetalol causes vasodilation, which reduces peripheral vascular resistance and lowers blood pressure.

​

​

                                                                                         Key points about Labetalol

​

• Labetalol exhibits selective alpha 1- and nonselective beta 1 and beta 2 adrenergic antagonist effects.

 

• The beta to alpha blocking potency ratio is 3:1 for oral labetalol and 7:1 for IV labetalol.

 

• Labetalol lowers systemic blood pressure by decreasing systemic vascular resistance (alpha 1 blockade).

 

• Orthostatic hypotension is the most common side effect of labetalol.

 

​​

 

​​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

 

​​

​​