HTN crisis

Question 1

HTN crisis is when there is a severe elevation in blood pressure. There are two categories of HTN crisis. First is HTN emergency. what is the definition of this?

Answer 1

Severe Hypertension
–greater than 210 (Systolic)
— greater than 150 (diastolic)
with signs of damage to target organs

Question 2

The second category of HTN crisis is HTN urgency, what is the definition of this?

Answer 2

Very high blood pressure
–greater than 120 diastolic
without any evidence of target organ damage
Immediate IV intervention is not needed but oral intervention and admission to the hospital is needed

Question 3

What are the treatment for Hypertensive Urgencies?

Answer 3

Adjust maintenance therapy by adding a new antihypertensive drug and or increasing the dose of a present medication

Question 4

What is the treatment for Hypertensive Emergencies?

Answer 4

Arterial line needed to monitor blood pressure
–pressure needs to be reduced using IV drugs
lower BP by no more than 25%
if stable, followed by further reduction towards a goal of 160/100 within 2-6 hours and then gradual reduction

Question 5

Now the rest of the cards will list the drugs used in HTN emergencies. The first is a parenteral vasodilator called Sodium Nitroprusside, what are the clinical applications?

Answer 5

Drug of Choice for HTN emergency
Heart Failure
Controlled Hypotension: reduce bleeding during surgery

Question 6

What is the mechanism of action for Sodium Nitroprusside?

Answer 6

Dilates both arterial and venous vessels

• -reduced peripheral vascular resistance
• -action occurs via activation of cGMP, through the release of NO
• -decrease in peripheral vascular resistance leads to an increase in cardiac output by decreasing afterload

Question 7

Sodium Nitroprusside is rapidly broken down to cyanide which is converted to thiocyanate. What is an adverse effect of this?

Answer 7

High doses or kidney or liver failure can result in cyanide and thiocyanate toxicity

• -very short duration of action
• light sensitive

Question 8

What are adverse effects of sodium nitroprusside?

Answer 8

Hypotension
Reflex tachycardia
Cyanide Toxicity

Question 9

HTN emergencies can be treated by another parenteral vasodilator called Nitroglycerin. What is the clinical application of this drug?

Answer 9

Management of HTN Emergencies: drug of choice in patients with cardiac ischemia or angina or after bypass
Acute decompensated heart failure
Controlled Hypotension

Question 10

What is the mechanism of action of Nitroglycerin?

Answer 10

Nitroglycerin forms nitric oxide —- nitric oxide activates guanylyl cyclase —- increases cGMP — smooth muscle relaxation
Vasodilator effect on peripheral veins and arteries (favoring veins more)
Reduces cardiac oxygen demand by decreasing preload, modestly reducing afterload, dilating coronary arteries and improving collateral flow to ischemic regions

Question 11

What is the duration of action of Nitroglycerin?

Answer 11

5-10 minutes after infusion

Question 12

What are adverse effects of Nitroglycerin?

Answer 12

Hypotension

Question 13

The next drug used in Hypertensive Emergencies is Esmolol, which is a B1 selective antagonist. What is the clinical applications, mechanism of action for this drug, pharmacokinetics and adverse effects?

Answer 13

Clinical:
--management of HTN emergencies in aortic dissection or postoperative hypertension 
Mechanism of Action
--blocks B1 receptors 
Pharmacokinetics:
--duration of action:10-20 minutes; onset of action: 1-2 min
Adverse Effects:
---Hypotension

Question 14

The next drug used in hypertensive emergencies is a Dopamine receptor agonist called Fenoldopam. What is the clinical applications, mechanism of action, pharmacokinetics and adverse effects?

Answer 14

Clinical:
–Management of HTN emergencies is patients with renal failure
MOA:
–agonist at dopamine-1 receptors resulting in arterial vasodilation — causes hypotension, increased renal blood flow, diuresis and naturesis
Pharmacokinetics
–Onset of action: BP reduction in less than 5 minutes
Duration of action:30 min
Adverse Effects:
Hypotension, reflex tachycardia
Contraindications:
–Glaucoma

Question 15

The next drug used in Hypertensive Emergencies is Nicardipine a calcium channel blocker, what is the clinical application, MOA, pharmacokinetics and adverse effects?

Answer 15

Clinical:
--Management of HTN and of HTN emergencies
MOA:
calcium channel blocker 
Pharmaco:
Onset of action: 2-10 minutes 
Duration of action: 40-60 min 
Adverse Effects:
Hypotension
Reflex tachycardia

Question 16

The next drug used in Hypertensive Emergencies is Phentolamine, an alpha receptor blocker. What is the clinical application, MOA, pharmacokinetics and adverse effects?

Answer 16

Clinical:
Management of HTN emergencies: tx of catecholamine related emergencies (pheochromocytoma, cocaine and amphetamine toxicity or clonidine withdrawal) 
MOA:
Alpha receptor blocker 
Pharmaco:
Onset of action: 1-2 minutes
Duration of action: 10-15 minutes 
Adverse Effects:
Hypotension and Reflex tachycardia

Question 17

The last drug used in Hypertensive Emergencies is Diazoxide, a potassium channel opener. What are the clinical applications, MOA, Pharmacokinetics, and Adverse Effects?

Answer 17

Clinical:
--Management of HTN emergencies 
--Tx of hyperglycemia secondary to insulinoma 
MOA:
--prevents vascular smooth muscle contraction by opening potassium channels and stabilizing the membrane potential at resting level 
Pharmaco:
Onset: 5 minutes 
Duration: 4-12 hours 
Adverse Effects:
Hypotension 
Reflex tachy
Na and H2O retention 
Inhibition of insulin release