Labetalol (Trandate)

Labetalol (Trandate)

Non-selective beta blocker

July 23, 2023

Dear colleagues:


Welcome! In this week’s Pharmacy Phriday, we will review Labetalol, one of the beta blockers that can be found in the UH drug box.  The other beta blocker available is Metoprolol.  The provider must be extremely cautious and prevent any mix-up between these medications.  They are different in how they work, their indications, and their dosing.


The difference between how the two medications work is that Metoprolol is a “selective” beta blocker, and Labetalol is a “non- selective” beta blocker.  In the case of Metoprolol, the receptors affected are primarily cardiac sites which result in decreased cardiac output.  With Labetalol, receptor sites affected also include beta 2 receptors (do you recall beta 2 – 2 lungs?) and some alpha receptors (do you recall alpha for arteries?) that inhibit peripheral vasoconstriction and leads to peripheral vasodilation.  These properties of Labetalol make it a potent agent for lowering blood pressure in cases of hypertensive crisis.


A common use of Labetalol includes the control of acute hypertension in pregnancy and hypertension associated with acute ischemic stroke.  The medication provides treatment in these hypertensive crises without reflex tachycardia or a significant reduction in heart rate. The use of the medication within the UH protocol is primarily focused on hypertensive crisis in pregnancy. 


Treatment in the prehospital setting of hypertensive emergencies other than supportive care, positioning, and transport is rarely indicated.  The increased blood pressure can often be a compensatory mechanism of the body in other underlying illnesses or conditions.  Only when the BP is extremely high and signs of end-organ damage, such as an altered mental status, chest pain, congestive heart failure, etc., does the blood pressure require treatment. Correction of hypertension associated with a stroke is a listed indication for the use of Labetalol but only in consultation with medical direction and is rarely seen in the prehospital setting.


However, hypertension during pregnancy is increasingly common and a leading cause of maternal mortality and morbidity and is one of the more common indications where treatment of hypertension may be addressed.  Severe hypertension requires prompt treatment with rapid-acting antihypertensive agents such as Labetalol to avoid stroke and placental abruption. 



UH protocol includes the administration of Labetalol in cases of eclampsia, pre-eclampsia, or post-partum hypertension only with online medical control approval. Blood pressures should be checked in both arms, with one taken manually. Hypertension is defined in this protocol as a systolic greater than 160 and/or a diastolic of 110, with symptoms. The initial dose is 20mg, administered as a slow IV push over 2 minutes to prevent a sudden, severe drop in blood pressure.  The medication can be repeated in five minutes if no improvement is noted, and the BP remains above the threshold cited in the protocol.  The second dose is 40mg, again as a slow IV.  


As with other beta blockers, the medic should monitor the patient continuously during and following administration for serious side effects that could include hypotension, bradycardia, dizziness, or arrhythmias.  Due to the alpha component of Labetalol causing vasodilation, the provider should also be alert for orthostatic hypotension and have the patient remain supine. 


Due to its inotropic effects, Labetalol is contraindicated in patients with known CHF. Other contraindications include bradycardia, heart blocks, cardiogenic shock, and other sinus arrhythmias.  It should also be used with caution in asthmatics, the elderly, and those with liver disease. 


Remember that there are two beta blockers in the UH drug boxes.  Both require medical direction approval for use.  And be sure you have the correct medication before administration!


Look for the next installment of the UH-EMSI Pharmacy Phriday when we will review past cases of pre-eclampsia and eclampsia within the UH system and discuss the use of another medication given in those emergencies.  Do you know the medication and dosing we will be reviewing?


Till then, stay safe!!




Sincerely,



The UH EMS-I Team

University Hospitals

August 15, 2022

Dear Colleagues,


In last week’s Pharmacy Phriday, we began a review of two similar-sounding medications that can be found in the UH drug box that could potentially confuse the provider.  Those two medications were Metoprolol and Labetalol, both beta blockers.  In that installment, we reviewed Metoprolol, and this week we will review Labetalol. 


Labetalol, like Metoprolol, is a beta-blocker.  The difference between the two medications is that while Metoprolol is a “selective” beta blocker, Labetalol is a “non-selective” beta blocker.  In the case of Metoprolol, the receptors affected are primarily cardiac sites, which result in decreased cardiac output.  With Labetalol, receptor sites affected also include beta 2 receptors (do you recall beta 2 – 2 lungs?) and some alpha receptors (do you recall alpha for arteries?) that inhibit peripheral vasoconstriction and lead to peripheral vasodilation. 


Due to the mixture of its alpha and beta blocking effects, a common “off-label” use of Labetalol includes the control of acute hypertension in pregnancy and hypertension associated with acute ischemic stroke.  The medication provides treatment in these hypertensive crises without reflex tachycardia or a significant reduction in heart rate. The use of the medication within the UH protocol is primarily focused on the hypertensive crisis in pregnancy. 


Education and training in prehospital emergency care often stress that an elevated blood pressure alone is not an emergency and that treatment in the prehospital setting for hypertensive emergencies other than supportive care, positioning, and transport is rarely indicated.  The increased blood pressure can often be a compensatory mechanism of the body in other underlying illnesses or conditions. The blood pressure requires treatment only when it is extremely high, and there are signs of end-organ damage such as an altered mental status, chest pain, CHF, etc.

 

However, hypertension during pregnancy is increasingly common and a leading cause of maternal mortality and morbidity worldwide and is one area where treatment of hypertension may be indicated.  Severe hypertension requires prompt treatment with rapid-acting antihypertensive agents such as Labetalol to avoid stroke and placental abruption. 


UH protocol includes the administration of Labetalol in cases of eclampsia, pre-eclampsia, or post-partum hypertension only with online medical control approval. Blood pressures should be checked in both arms, with one taken manually. Hypertension is defined in this protocol as a systolic greater than 160 and/or a diastolic of 110, with symptoms. The initial dose is 20mg administered as a slow IV push over 2 minutes to prevent a sudden, severe drop in blood pressure.  The medication can be repeated in five minutes if no improvement is noted and the BP remains above the threshold cited in the protocol.  The second dose is 40mg, again as a slow IV.  


As with other beta-blockers, the medic should monitor the patient continuously during and following administration for serious side effects including hypotension, bradycardia, dizziness, or arrhythmias.  Due to the alpha component of Labetalol causing vasodilation, the provider should also be alert for orthostatic hypotension and have the patient remain supine. 


As with other beta-blockers, Labetalol has inotropic effects reducing the strength of cardiac contractions and may cause acute left ventricular failure in patients with known CHF, one of the contraindications to its use. Other contraindications include bradycardia, heart blocks, cardiogenic shock, and other sinus arrhythmias.  It should also be used cautiously in asthmatics, the elderly, and those with liver disease.  Under the pregnancy class rating, the medication is classified as class C.


Remember that there are two beta-blockers in the UH drug boxes available.  Both require medical direction approval for use.  And be sure you have the correct medication before administration!


Have a great weekend!  And stay safe!!




Sincerely,


The UH EMS-I Team

University Hospitals