Cardio: Vasodilator Drugs Flashcards Preview

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Flashcards in Cardio: Vasodilator Drugs Deck (14)
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1

  • ↓ TPR via dilation of both  Arteries and Veins
  • onset time in seconds (arterial afterload and venous preload) w/ small cardia reflex stimulation
  • Cyanide toxicity can lead to acid-base disturbances, arrhythmias, and SCD  → co-administer w/ Nitrites and Thiosulfate to decrease toxicity (24 - 36 hrs max)
  • Thiocyanate toxicity seen in pts. with impaired Renal failure --> disorientation, psychosis, spasms, convulsions
  • DOC in Hypertensive Emergencies and Severe cardiac failure in conjuction with Furosemide (prevent overload)

Sodium nitrorusside

2

  • Dihydropyridine calcium channel blockers with onset time in 1 - 5 or 2 - 4 minutes
  • One of these two has a long terminal half-life

Nicardipine or Clevidipine (long half-life)

3

  • A Dopamine receptor-1 agonist (DA1) with onset time in 4-5 minutes
  • Maintains or increases Renal Perfusion and may be good choice for patients with Renal dysfunction
  • Reduces Blood pressure
  • Used in Emergency Hypertension

Fenoldopam

4

  • A venous arteriolar dilator with onset time in 2-5 minutes is more effective as a Venous rather than as a Arteriolar dilator
  • Has been used for treatment of HTN crisis in pts. with Cardiac Ischemia or after Coronary bypass surgery

Nitroglycerin

5

  • A non-selective α-blocker with onset time in 1-2 minutes
  • Used to treat pts. w/ Catecholamine-related emergencies

Phentolamine

6

  • A β-blocker with onset time in < 5 minutes
  • Used to treat Aortic Dissection or Postoperative HTN

Esmolol

7

  • A α- and β-adrenergic blocker with onset time in 5-10 minutes
  • May be safe in pts. with active Coronary disease

Labetalol

8

  • Arteriolar dilator with onset time in 10-30 minutes
  • Increasing K+ efflux, decreasing Ca2+ influx, NO release
  • Direct relaxation of the Arteriolar smooth muscle
    • ​→ ↓↓ TPR via arteriolar dilation (afterload) and BP
    • reflex ↑ in HR, Contractility, Plasma renin, and fluid retention → use w/ Diuretics
  • Tx: Mod- to Hypertensive emergencies in pregnancy related to eclampsia, Chronic hypertension
  • Contraindicated in pts. with HTN and CAD, may produce SLE like symptoms in slow acetylators (high protein binding w/ free faction), Edema, and reflex Tacycardia

Hydralazine (Apresoline)

9

  • Block adrenergic neuron function
  • Exogenous false neurotransmitter (replaces norepinephrine in storage vesicles) → NorEpi release
  • Inhibits the function of peripheral postganglionic adrenergic neurons
  • Effector cells become supersensitive to Norepinephrine

Guanadrel (Hylorel)

10

  • Blocks adrenergic neuron function
  • Depletes amines in the CNS as well as peripheral adrenergic neuron
  • Interferes with sympathetic nervous function
  • Binds to adrenergic storage vesicles and inhibits vesicular catecholamine transporter that facilitates vesicular storage → pharmacological sympathectomy

Reserpine

11

  • Centrally acting sympatholytic agents
  • Stimulate the α2A-adrenergic receptors in the brainstem
  • Reduction in sympathetic outflow from the CNS → Hypotensive effect
  • High Dose → activate α2B-adrenergic receptors on vascular smooth muscle → Loss of therapeutic effect

Clonidine (Catapres)

Guanabenz (Wytensin)

Guanfacine (Tenex)

12

  • ATP K+ channel Opener → metabolized to active metabolite minoxidil sulfate that activates the
    ATP-modulated K+ channel in Arteriolar smooth muscle (hyperpolarize)
    • → little effect on Venous and Capacitance vessels
  • Side effects: ↑ HR, Contractility, Plasma renin activity and Fluid retention, also ↑ oxygen demand can lead to cardiac ischemia and is contraindicated in HTN pts.
  • Tx: HTN refractory, Hypertrichosis, Hyperglycemia (Diazoxide surpresses insulin release)
  • Co-administed with sympatholytic agents, β-blockers

Minoxidil → Severe Hypertension and Baldness (Rogaine)

Diazoxide → Emergency Hypertensive

Cromakalim

Pinacidil

Nicorandil

 

13

  • Ca2+ channel blocker - Dihydropyridine
  • Arteriolar dilators
  • Decreased entry of Ca2+ by binding to α1 subunit of L-type channels → intracellular [Ca2+] low 
    → reducing activation of myosin light chain kinase, actin-myosin interaction, and smooth muscle contactility
  • Arteriolar more responsive then Venous
  • ↓ Contractility by reflex, ↓ SA node rate, ↓ AV node conduction velocity, ↑ HR by reflex
  • Tx: HTN, HTN emerg., Angina, HF, prevent neuro deficits secondary to Cerebral Artery Spasm

Nifedipine (Procardia)

14

  • Ca2+ channel blocker - Non-dihydropyridine
  • Arteriolar dilators
  • Decreased entry of Ca2+ by binding to α1 subunit of L-type channels → intracellular Ca2+ low 
    → reducing activation of myosin light chain kinase, actin-myosin interaction, and smooth muscle contactility
  • Arteriolar more responsive then Venous
  • ↓↓↓ Contractility by reflex, ↓ SA node rate, ↓↓ AV node conduction velocity, ↓↓↓ HR, ↓↓↓ Ca2+ recovery
  • Tx: HTN, HTN emerg., Agina, HF, prevent neuro deficits secondary to Cerebral Artery Spasm

Verapamil (Isoptin)