Thursday, May 15, 2008

Cardiovascular Drugs Made EZ: Part 1

Pharmacology is a key subject when studying for any healthcare board exam, such as the NCLEX or USMLE. This word can be a simple stimulus for nightmares in many in nursing or medical school studying for their boards. We are going to take a multi-part look at this subject by looking at one of the biggest classes of drugs that you will need to know: Drugs effecting the heart and vasculature.


This is a huge class of drugs, accounting for a huge chunk of the drugs that we actually need to know well, and is one that the NCLEX and USMLE are going to ask you about. Lets break this class down into smaller, more manageable chunks. We will start with drugs used to treat Hypertension, as this class is very large and very important. First of all, take a look at the picture below for a summary of the drugs we will discuss.





ACE Inhibitors

Names:
• “Prils” Think an ACE is a Pro (kinda like a pril)
• Examples: Enalapril (Vasotec), Captopril, Lisinopril
Uses:
• Hypertension, Heart Failure, Protection for diabetics vs nephropathy, Decrease Mortality in post-MI patients due to afterload reduction
Action:
• blocks the enzyme that converts angio I to angio II in the lungs. Angio II leads to vasoconstriction, aldosterone release, and sodium retention: this is blocked, which decreases blood pressure and puts less strain on heart
Common Side Effects:
Dry hacking cough; Angioedema; Hyperkalemia
• Taste disturbance; Rash; Insomnia, Orthostasis
Nursing Implications:
• CI: Pregnancy Category D; Bilateral Renal Stenosis
• Use K supplements carefully due to hyperkalemia concerns
Stop drug if cough, angioedema
• Taste of food may be diminished during first month of therapy


Angiotensin Receptor Blockers (ARBs)
Names:
• “Sartans”
• Examples: Losartan (Cozaar), Irbesartan, Valsartan (Diovan)
Uses:
Hypertension, Heart Failure
Action:
• Blocks the receptor for Angiotensin II, blocking the effects of this potent vasoconstrictor
Common Side Effects:
• Hyperkalemia, Angioedema, Orthostatic hypotension
Nursing Implications:
• CI: Pregnancy Category D in 2nd/3rd trimesters; Bilateral Renal Stenosis
• Safer side effect profile than ACE inhibitors but less studied



To understand ACE and ARB it is vital that you have an idea of what the Renin-Angiotensin-Aldosterone System (RAAS) is. Remember the purpose of RAAS is to increase blood pressure in response to decreased renal blood flow or pressure, and the purpose of the drugs that work here is to block this system and lower blood pressure. Check out the pick below for a summary of the RAAS and where certain drugs work.




Beta Blockers (or beta antagonists)

Names:
• “OlOls: Remember Beta video tapes? They are OLdOLd
• Ex: Selective B1: Metoprolol, Atenolol (I MET A TEN last night)
• Ex: B1B2: Propanolol (Inderal), Labetalol, Carvedilol (Coreg) (ilol, alol-also alpha blocker)
Uses:
Hypertension, Angina, Arrhythmias, Glaucoma, MI prophy, Migraines
Action:
• Block adrenergic Beta receptors (1 heart, 2 lungs), leading to lower sympathetic activity = decrease in cardiac output, blood pressure and renin activity. Also some drugs lower aqueous humor production
Common Side Effects:
Bradycardia, fatigue, insomnia, bizzare dreams, sex dysfunction, lipid dysfunction; Respiratory distress (wheezing), Agranulocytosis, depression
Nursing Implications:
C/I in asthma, bradycardia, severe renal/hepatic disease, hyperthyroid, CVA
Signs of hypoglycemia (DM), tachycardia (hyperthyroid) may be masked
Glucagon may reverse overdose


Calcium Channel Blockers (Antagonists)

Names:
• Dihydropyridines: “Pines”: Amlodipine (Norvasc), Nifedipine (Procardia)
• Non-Dihydropines: Diltiazem (Cardizem), Verapamil
Uses:
Angina, Arrhythmias (Non-D’s have more AV node effect)
Hypertension (Dihydro’s have more vasodilation effect)
HT (Pines), Dysrhythmias (Verapamil), HT/Dys (Diltiazem)
Action:
• Blockade of Ca channels causes arteries to relax (vasodilate) and cardiac conduction to slow through the AV node
Common Side Effects:
All: H/A, hypotension, dizziness, peripheral edema, Renal/Hepatic dysfunction
Dihydros: Ankle edema, flushing, tachycardia, gingival hyperplasia
Non-D’s: AV block, bradycardia, worsened systolic dysfunction
Nursing Implications:
Use very cautiously with heart failure/left ventricle inpairment, AV block
Don’t abruptly stop medication; Warn patient to contact MD if irregular HR, SOB, swelling, pronounced dizziness, constipation, nausea, hypotension


Peripheral Alpha Blockers

Names:
• Mixed names: “Zosins” for BPH, “ilol” for HT;
• Examples: Carvedilol (Coreg), Tamulosin (Flomax), Prazosin (Minipress)
Uses:
Hypertension, Peripheral Vascular Dz (raynaulds, phlebitis, etc), BPH
Action:
• Blockade of Alpha 1 relaxes smooth muscle in arteries and prostate capsule, leading to lower blood pressure, reduction in BPH, and increased blood in tissues (warm/pink skin) as well as Renal arteries
Common Side Effects:
Orthostatic Hypotension (especially first dose), Reflex Tachycardia, Ejaculation problems, nasal congestion
Nursing Implications:
• Begin with small dose and give at bedtime to avoid dizziness and syncope
Change positions slowly to decrease orthostatic hypotension
Alcohol, Excessive exercise, prolonged standing, heat make S/E worse

Central Alpha Blockers

Names:
Clonidine (Catapres); Methyldopa (Aldomet)
Uses:
Hypertension
Action:
• Central acting sympatholytic stimulates pre-synaptic alpha receptors to release NE, which paradoxically reduces peripheral NE release, inhibiting vasoconstriction = vasodilation and lower BP
Common Side Effects:
• Sodium/Water retention, Dry mouth, Bradycardia, Impotence, Depression
Nursing Implications:
Advise patient not to abruptly withdrawal because significant rebound hypertension can result
C/I in impaired liver function so monitor liver function tests occasionally
Do not confuse with the benzo Klonipin (patients have done so and taken a bunch of Clonidine for a high, only to end up with a real low…BP that is.


Diuretics

Types:
Loop: Furosemide (Lasix), Bumetanide (Bumex), Torsemide (Demadex)
Thiazide: Hydrochlorothiazide (HCTZ)
K-sparing: Amiloride, Spironolactone
Carbonic Anhydrase Inhibitors: Acetazolamide (Diamox)
Uses: Edema associated with heart failure; Ascites with Cirrhosis; Hypertension
Action:
Loop: Inhibit Na, Cl, and H2O resorption in the loop of henle thus decreasing blood volume; Also increase the excretion of K; Potent diuretics
Administer IV Lasix slowly because hearing loss can occur if given rapidly
Thiazide: Inhibit Na resorption and increase Cl, H2O, K, Ca, Bicarb, Mg excretion in the urine; Also cause arterial dilatation; Moderate diuretic
• While K and Na may be excreted, HyperCa is more likely to develop so never administer to patient with hypercalcemia;
• Eat foods rich in potassium, use sunscreen, and change position slowly
Caution when taking with Lithium, Digoxin, Corts, PO Diabetic meds
K-sparing: Block Na-K exchange in distal tubule causing loss of Na and water and retention of K; Weak diuretic mostly added to preserve K
C/I in severe renal/hepatic dysfunction, hyperkalemia, Current ACE-I use
Carbonic anhydrase inhibitors:
Used to treat M.Alkalosis, Open Angle Glaucoma, Epilepsy, High altitude sickness
• Inhibits the enzyme carbonic anhydrase which normally is responsible for excreting H to combine with HCO3 for elimination of excess acidity, as well as promoting diuresis. This drug obviously leads to an increase level of H+ in the blood (M.Acidosis) and an increased excretion of Bicarb (HCO3)
C/I with CLOSED (narrow) angle Glaucoma
S/E i/c Renal Calculi, Hypercalcemia, and Hemolytic anemia
Common Side Effects:
Loop/Thiazides: Hypokalemia, Hyperuricemia, Glucose intolerance, sexual dysfunction, increase cholesterol/triglyceride levels
K-Sparing: Hyperkalemia especially when used with ACE inhibitors
Nursing Implications:
• Caution for electrolyte disturbances; Watch for cramping, paresthesia
Administer in morning to avoid diuresis during night, Supplements (PhosLo)

21 comments:

Anonymous said...

Great post!
I take my EKG test next week as a part of the critical care fellowship that I am lucky to be in.
Glad to have come in.
Krista, GN (maybe RN as of tomorrow!)

Anonymous said...

Thank you very much for the concise and easy to understand info. I will be sharing this with my students, both classroom and clinical! Where did you find the pics for HT and Cardiac drugs? They are great but got fuzzy when I saved them to my personal notes. I teach senior nursing students. Thanks again!

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Anonymous said...

Great post! Thank you for breaking it down. It's really helping me as I study for my nursing finals.

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This is such a great post!!! Thank you sooo much!!

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jasicac Craferd said...

First off, good luck to everyone taking this test. I can barely imagine how tough it is to go through medical study, much less memorizing all those terms, and in a pattern, repeatedly. Always try to find a mentor or an assistant, in providing you the references and text books, and helping you get through pages of them, whatever review materials you use.
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Manjot kaur said...

Nice blog! Very interesting and informative post….Thank's for sharing such a nice information….Keep it up!!

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Anonymous said...

Clonidine and methyldopa* are not central alpha receptor blockers. In fact, they are the opposite. The are central alpha (alpha-2) receptor agonists. That is, they stimulate the alpha-2 receptor pre-synaptically which inhibits further norepinephrine release. This reduces sympathetic outflow from the CNS and decreases peripheral resistance, renal vascular resistance, heart rate, and blood pressure.

*methyldopa gets converted to alpha-methylnorepinephrine, a potent alpha-2 agonist.

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