11.02 Sympatholytics (Alpha & Beta Blockers)
A. Autonomic nervous system = PNS & SNS
B. Sympathetic neurotransmitters all over body
1. Adrenergic 1 / 2
a. Varying location and nerves, all over body
2. Beta 1 = Heart (cardio-selective)
3. Beta 2 = BV, bronchioles, smooth muscle
II. Mechanism of Action
A. Inhibit stimulation of SNS (flight or fight)
B. Think inhibit stress response
1. Decrease HR
2. Decrease BP
3. Arterial / Venous dilation
4. Smooth muscle relaxation
B. Cardio-selective Beta-Blockers (B1)
C. Non-selective Beta-Blockers (B2)
5. Urinary flow obstruction
6. Raynaud’s disease
3. Heart failure
4. Cardiac-protective (after MI)
2. Hepatic / renal disease
3. Coronary artery disease
1. Uncompensated heart failure
2. Cardiogenic shock
3. Heart block or bradycardia
4. Severe pulmonary disease
VI. Side Effects
4. Chest pain
1. N / V / D
D. * Beta-Blockers
3. Rebound tachycardia (if stopped abruptly)
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Welcome back and today we are doing to discuss sympatholytics.
Sympatholytics work on the autonomic nervous system, mainly the SNS and their neurotransmitters – Adrenergic (which is various locations, think adrenergic = all over) and beta1 (heart) and beta 2 (BV, bronchioles, and smooth muscles).
Now sympatholytic work by inhibiting SNS, so the flight to fight response are inhibited… resulting in lower heart rate, blood pressure, dilation and relaxation. Think the opposite of stress. When you are stressed, you are tachycardic and HTN and generally not relaxed, haha.
Let’s review alpha types, they all tend to end in -OSIN. Do focus on memorization, focus on the ending here.
Next we have beta-blockers. The first section is cardioselective (works mainly within the heart). Non-selective is below and focuses on BV, bronchioles and smooth muscles. Regardless, the ending is -LOL.
Indication for alphas include the following. I want you to focus on what the drug does… inhibit stress responses. So therefore, we are attempting to relax SM, decrease HR and decrease BP. Each indication focuses on those three principles.
Indications for betas focus on the same concept. We are attempting to inhibit the stress response. Angina, HTN, heart failure all stress the heart. Beta-blockers will assist in slowing things down and improving cardiac output.
Contraindications focus on high risk patients populations. in PVD (these drugs cause intermittent claudication, which isn’t good), heart block will be exacerbated with the use of these drugs. The goal here is to assist the heart and vasculature NOT cause more harm.
Cardiac side effects include palpitations, hypotension, bradycardia and chest pain. All of which result from the drug working too well. When the heart beats too slow, my impairs oxygen to the heart, which can cause chest pain. Too low BP = hypotension.
Next we have CNS side effects which can include headache, dizziness, anxiety and vertigo. Again, if you are dilating, previously constricted areas, dizziness and headaches are common. Focus more on the drug’s action and less of memorization.
Lastly, let’s review unique side effects of beta blockers which include hypoglycemia, bronchospasm, round bound tachycardia and hypotension. If you patient has COPD or is a brittle diabetic, this drug class will be a tough one to manage. Again we are trying to assist not harm so keep these in mind. If a patient for example is admitted with sepsis and has an admitting BP of 80/60, you wouldn’t want to administer their beta-blocker as it will cause more profound hypotension. This is why sympatholytics tend to have BP parameters for administration. You want to check your patient’s BP and HR before administering any sympatholytics, in general.
Priority nursing concepts for a patient receiving sympatholytics include anatomy, perfusion and pharmacology.
Alright let’s review the key points: The how: Inhibition of SNS (flight to fight response). Second, we have the different types -OSIN and -LOL. Indications vary but include HTN, migraines, heart failures, among other things. Contraindications include PVD, heart block and pulm disease. Lastly, we reviewed side effects which included cardiac, CNS, GI and special mentions regarding beta-blockers.
Now you know all you need to know about sympatholytics. Now go out and be your best self and happy nursing!