Cardio-pharm-antihypertensives I- Mortensen Flashcards
What type of drug is adenosine?
antidysrhythmic
Why is adenosine so susceptible to degradation in the body?
It is a purine nucleoside, it has a very short half-life
Adenosine subtype receptor A1 is found on which type of cells?
AV nodal cells which stimulate opening of membrane K+ channels
Adenosine stimlates A1 receptors on AV nodal cells which open K+ channels, what happens to the AV nodal tissue?
AV nodal hyperpolarization and complete AV nodal block, it becomes
What is adenosine used for in its capacity of a short acting AV nodal blocker?
conversion of reentrant SVT (PAT, PSVT and WPW) to NSR
What is the preferred route of administration of adenosine?
IV • rapid bolus at 6-12 mg, proximal to heart (brachial vein, antecubital) because of rapid half-life of 15 s.
Why are we not too concerned about ADEs of adenosine?
too fast to be concerning
: hypotension, flushing, complete heart block, CNS effects, dyspnea
There are two important MOAs for digoxin: What are they and which MOA is useful as an AV nodal blocker or sifter?
- CHF – Na+/K+-ATPase inhibition- increases contractility by keeping Ca2+ inside cell
- Atrial Fib. – vagal stimulation effect resulting in a negative dromotropic effect at the AV node resulting in prolonged refraction (↑ERP)
Which type of medicine is preferred as AV nodal blockers for treating AFIB over digoxin?
Calcium channel blockers
Which antihypertensive is considered a cardiac glycoside and has 2 MOAs:
- CHF – Na+/K+-ATPase inhibition
- Atrial Fib. – vagal stimulation effect resulting in a negative dromotropic effect at the AV node resulting in prolonged refraction (↑ERP)
digoxin
• in atrial flutter/fibrillation, digoxin slows ventricular rate by decreasing the number of P-wave depolarizations that reach the ventricles, however, stimulation may over-ride this therapeutic effect because of the dual MOAs.
sympathetic
As concerning pharmacokinetics: Digoxin is soluble and can access the CNS and placenta
lipid soluble
Some of the main ADEs of digoxin include :
• highly dysrhythmogenic (prodysrhythmic) due to effects on plasma potassium (hypokalemia)
Which categories of antidhysryhtmics are useful in treating digoxin induced dysrhythmia?
Class IB and Class II agents
What are 3 treatments for bradycardia?
atropine – produces a vagal block to increase HR •
isoproterenol – β1-stimulated increase in HR •
pacemaker – morphologic AV nodal bloc
What is the MOA of atropine?
– produces a vagal block to increase HR, blocks parasympathetics
Isoproterenol is a agonist and can HR and can treat bradycardia
B1; increase
Pacemakers mainly treat ?
bradycardia which can be caused by morphologic AV nodal block
What are some non pharmacologic ways to treat sinus tachycardia?
vagal stimulation through carotid sinus massage or Valsalva maneuver- causing baro-reflex and reducing HR
Which nerve is mainly involved with the carotid sinus?
glossopharyngeal nerve (IX)
Which other elements are involved with the carotid sinus and the baroreceptor reflex?
Nucleus tractus solitarus, area postrema, rostral and caudal ventral lateral medulla, and CN IX
What elements are involved with the efferent part of the baroreceptor reflex?
Info comes back through the vagus nerve (X), cardiac accelerans, and other medullary efferents to increase or decrease HR, vasocontsriction, and renal function.
• eclampsia/preeclampsia • endocrine disorders (e.g. Cushing’s Syndrome) • pheochromocytoma • renal disease • essential hypertension are all causes of blood pressure
high
There are 2 major types of HTN which are:
Non-essential/secondary (10%) • a clinically identifiable cause (e.g. renal disease, endocrine tumors, aortic stenosis, etc.) • primary management is usually surgical
• Essential/primary (90%) • idiopathic • a genetic basis for incidence most often found in middle-aged adults
First line recommendations for HTN is not medications, but ?
lifestyle modifications
Lose weight if overweight •
Limit alcohol intake to ≤1 oz (30mL) per day •
Aerobic physical activity (30-45 min per day) •
Reduce Na+ intake to ≤100mmol (6g) per day •
Maintain intake of K+ to ~90mmol (7g) per day •
Maintain intake of Ca+2 and Mg+2 •
Stop smoking and reduce dietary intake of sugar, saturated fat and cholesterol
What level of BP is the pharmacological tx goal for HTN:
<130/85
• Chronic hypertension usually ‘resets’ the baroreflex such that the pressure is considered normal.
increased
Must find a HTN treatment plan that will best combat the effects of the .
Baroreflex
sodium and water retention by the kidneys and sympathetically-induced increases in peripheral vascular resistance, heart rate and cardiac output are all mechanisms by which the can try to increase BP to what it considers normal (but is acutally high BP) while the provider trys to lower BP
baroreflex
According to the formulas:
MAP = CO × TPR
CO = HR × SV
you can lower BP (MAP) by decreasing HR, SV, and/or TPR (systemic vascular resistance)
Diuretics are used to treat which type of BP?
moderate HTN as a monotherapy
but also augments antihypertensive effects of other drugs
What 3 types of diuretics have been discussed?
• thiazides, loop diuretics, K+-sparing diuretics
Efficacy of diuretics is greater in which two populations?
African-American and elderly patients
What are the effect of diuretics on CO and TPR?
initial ↓CO followed by sustained ↓TPR
When do you expect to see peak effects after starting diuretics?
3-4 months
What 2 contraindications are important in the use of diuretics?
- diabetics : may induce hyperglycemia
- hyperlipidemia: tend to elevate plasma LDL and TG
What type of pharmacologic agent is propranolol?
β-adrenergic antagonist
The main effect of B blockers is at which receptor in order to lower BP?
B1 receptors
What are the MOAs of β-adrenergic antagonists (B-blockers) like propranolol?
- heart: ↓HR/contractility ⇒ ↓blood pressure
- kidney: ↓renin release ⇒ ↓Angiotensin II formation
both lower BP
Beta blockers work at which parts of the heart to be effective?
The nodes and the conductile tissues of the ventricles
Like diuretics, the efficact of monotherapy with b blockers is and it works better in a combination therapy
moderate
B blockers and are often used together, to lower the dose of each and get a broad and wide range of antihypertensive effects
diuretics