Midterm 2 Flashcards by G X

Verapamil / Diltiazem

L-type (vg) Ca2+ channel blockers
Class 4 anti-arrhythmics
tx of supraventricular arrhythmias
↓ Ca2+ entry in SA + AV nodes = ↓ conduction, hr, contractility
pro-arrhythmic action if shortened action in ventricles

anti-anginal drug - ↓ cardiac work
reduce contractility, hr, + afterload

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Nifedipine

Dihydropyridine
L-type Ca2+ channel blocker
tx of hypertension angina - ↓ cardiac work
reduce contractility, hr, + afterload

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Thapsigargin

blocks SERCA pump (pumps Ca2+ into SR)
experimentally raises cytoplasmic Ca2+ levels

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Ryanodine

agonist of RyR
activates receptor at nanomolar [] but closes receptor at micromolar []

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Caffeine (methylxanthine)

sensitizes RyR
causes Ca2+ release from SR at physiological [Ca2+]

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Dantrolene

blocks RyR
used to treat malignant hyperthermia

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Isoprenaline

B1 agonist = sympathetic stimulation of heart
Gs → AC → ↑cAMP → PKA phosphorylation of L type Ca2+ channels
1. positive chronotropic effect
2. positive inotropic effect
3. ↑ A-V conduction = ↓ PR interval + ↑ hr
4. shortens ventricular AP duration
5. ↑ purkinje fiber rhythmicity
6. facilitates generation of EADs and DADs

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Muscarine

M2 receptor agonist = parasympathetic stimulation of supraventricular tissues
Gi → ↓ AC → ↓cAMP
1. negative chronotropic effect
2. shortens ap duration + reduces refractory period (atria)
3. blocks A-V conduction = ↑ PR interval

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Atropine

tachycardia + ↑ AV conduction
muscarinic antagonist = ↓ parasympathetic tone

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Quinidine, Procainamide, Dysopyramide

Class 1a anti-arrhythmics

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Lidocaine

Class 1b anti-arrhythmics
Na+ channel blocker → direct effect on cardiac myocytes
use dependent effect = only slows rate of rise of phase 0 in damaged tissue (blocking action is more potent when ion channels are open)
↓ automaticity
good for ventricular arrhythmias
short half life (~20min)

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Propafenone, Encainide, Flecainide

Class 1c anti-arrhythmics

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Propanolol + Metoprolol

B-blockers
Class 2 anti-arrhythmics → predominant action on sinus node
negative chronotropic + inotropic effects
contraindicated in acute hf, asthma, arrhythmias w AV block

anti-anginal drugs - prolong diastolic time
↓ hr = ↑ coronary perfusion time
↓ bp = ↓ afterload = ↓ cardiac work
used to prevent re-infarction after first MI (prophylaxis)

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Amiodarone

Class 3 anti-arrhythmics
K+ channel blockers = prolong ap duration (phase 3)→ longer refractory period
adverse effects:
- iodine toxicity: requires monitoring
- TdP → long QT

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Terfenadine

(Seldane)
antihistamine → when used with CYP3A4 inhibitor, can lead to TdP

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Digoxin

cardiac glycosides
uncommonly used anti-arrhythmic
slows AV conduction via ↑ vagal tone = tx of a-fib
low therapeutic window

tx of chronic heart failure
positive inotropic agent = ↑ contractility
negative chronotropic effect = no reflex tachycardia + vasoconstriction
↓ edema = ↑ glomerular circulation

inhibits Na+/K+ ATPase = reduced Na+/Ca2+ exchange = ↓ Ca2+ exiting cell during plateau phase of ap

Dobutamine

catecholamine - positive inotropic agent
tx of acute heart failure
cardiac B1 agonist = ↑ Ca2+ influx through L type Ca2+ channels
positive chronotropic effect

Amrinone

+ milrinone
phosphodiesterase inhibitors - positive inotropic agents
tx of chronic hf - oral or IV administration
↑ cAMP = ↑ Ca2+ = ↑ contraction of heart

(↓ contraction of vasc smooth m. - cAMP phosphorylates myosin LC kinase = inactivation → relaxation)

Glyceryl Trinitrate

nitroglycerine
anti-anginal drug - lowers LVEDP
venodilator → reduces workload via ↓ SV + art. pressure
produces coronary vasodilation without producing coronary steal
side effects: headache + tolerance

Acetylsalicylic acid

aspirin
emergency tx + prophylaxis of acute myocardial infarction
breaks up clot / prevents clot formation

Enalapril, Captopril, Ramapril

ACE inhibitors = stop angiotensin II synthesis → vasodilation
Na+ loss = fluid loss; K+ retention
prevent catabolism of bradykinin = antihypertensive
↓ afterload, ↓ preload
adverse effect: dry cough

Losartan, Valsartan, Candesartan, Telmisartan

Angiotensin receptor antagonists (ARBs)
↓ afterload
no dry cough side effect

Hydralazine, Nitroprusside

Vasodilators
anti-hypertensives

Acetazolamide

diuretic
carbonic anhydrase inhibitor (PCT) = excretion of Na+ + HCO3- (natriuresis)
tx: glaucoma, high altitude disorders, epilepsy, urine alkalinization
adverse effects: metabolic acidosis, allergic rxn to sulfa, hypokalemia

Mannitol

osmotic diuretic (PCT + desc LoH) tx: ↓ intracranial pressure, cerebral edema, glaucoma

Furosemide, Bumetanide

(high ceiling) loop diuretics inhibit NKCC2 in thick asc LoH → natriuresis tx. of hypertension, hf, cirrhosis, edema, nephrotic syndrome adverse effects: hypokalemia, hypomagnesemia, metabolic alkalosis, ototoxicity tx of heart failure - relieve edema + work load (↓ bp) some vasodilatory action high ceiling = ↑ therapeutic flexibility

Bartter syndrome

mutations = ↓ function of NKCC2 or ROMK mimic effects of loop diuretics = hyponatremia, -kalemia, -magnesemia

Hydrocholorthiazide

diuretic inhibits NCC in DCT → natriuresis tx of hypertension, edema due to nephrotic syndrome, renal disorders, prevention of kidney stone recurrence adverse effects: hypokalemia, -natremia, hyperuricemia, impaired glucose tolerance (↓ insulin release)

Chlorthalidone, Indapamide

thiazide-like drugs same mechanism of action, no benzothiadiazine ring

Gitelman syndrome

mutation in NCC transporter mimics effects of thiazide diuresis = hypokalemia, metabolic alkalosis

Amiloride

K+ sparing diuretic inhibits ENaC in principal cells = natriuresis tx of hf with hypokalemia or hypertension

Spironolactone, eplerenone

K+ sparing diuretic competitive antagonists of aldosterone = acts in principal + intercalated cells transcriptional mechanism of action = slow onset of action tx of hf with hypokalemia or hypertension, hyperaldosteronism adverse effect: antiandrogenic effect → gynaecomastia + impotence in males, menstrual irregularities in females tx in hf → renal K+ retention, Na+ loss, H20 loss

Tolvaptan

antidiuretic hormone antagonist blocks V2 receptor tx. of hyponatremia (associated with cirrhosis) adverse effect: thirst, polyuria

Empagliflozin

SGLT2 inhibitor in PCT = glucosuria + natriuresis used in tx of type 2 diabetes preference: ↓ sympathetic activity, preserved K+ balance, ↓ risk of acute renal injury, ↓ serum uric acid level

Dapagliflozin

SGLT2 inhibitor approved tx for hf