VASODILATORS

Question 1

Hydralazine is a __________ and is HIGHLY SELECTIVE FOR __________

Answer 1

Direct acting arterial vasodilators

Arterial resistance vessels

Question 2

Hydralazine MOA

Answer 2

Not clear

Causes DIRECT RELAXATION of vascular smooth muscles of arterioles.

Question 3

What causes the Vascular relaxation seen with hydralazine

Answer 3

1. Hyperpolarizing vascular smooth muscles cells by opening high conductance Ca2+ activated K+ channels
2. Also by activating Guanylate cyclase which increases cGMP –> leading to Inhibiting accumulation of intracellular calcium

Question 4

CV effects of Hydralazine

SVR, BP, ___more than ____(SBP, DBP)

Answer 4

Decreased SVR –> Decreased BP (DBP more than SBP)

Vasodilation more pronounced in Coronary, cerebral, renal and splanchnic

Question 5

**Biggest problem with HYDRALAZINE

Answer 5

REFLEX TRACHYCARDIA

Question 6

Indirect action of hydralazine

Answer 6

Positive INOTROPE

Tachyphylaxis can also developed

Question 7

CV effects is associated with powerful

Answer 7

Hydralazine-induced vasodilation stimulation of the SNS (via baroreceptor-mediated reflexes) which results in:
• ⇑ HR & ⇑ FOC.
- Also ⇑ plasma renin activity which ⇑ fluid retention. As a result of these actions, you see an ⇑ stroke volume & ⇑ CO.
• Following IV administration to patients with CAD, the myocardial ischemia may be sufficiently severe and can cause an MI

Question 8

**Hydralazine and MI

Answer 8

Myocardial ischemia can occur on account of ⇑ O2 demand induced by
the baroreceptor reflex-induced stimulation of the SNS

Question 9

Metabolism of Hydralazine

Answer 9

NonCYP 450 enzymes
CANNOT BE INDUCED or INHIBITED
ACETYLATION of enzyme N-acetyltransferase for ORAL hydrazine.
t 1/2 = 2-3 hours

Question 10

Antihypertensive effects do

Answer 10

NOT correlated with t1/2 and usually last 3-6 hours but can persist for up to 12 hours (NO CLEAR explanation for this

Question 11

2 types of acetylators: (GENETICally determined)

Answer 11

Rapid acetylators: Decreased hydralazine plasma levels

Slow Acteylators: Increased Hydralazine plasma Levels

Question 12

**Hydralazine

Answer 12

Dose does not correlate with half life.

Question 13

Acute IV hydrazine effects

Answer 13

REFLEX TACHYCARDIA
hypotension
headaches

Question 14

Clinical uses of HYDRALAZINE
2 main indications: Dosing for each
Onset causes what?
Caution

Answer 14

• Intraoperative hypertension
• Administer 2-10 mg IV bolus
• Onset: usually decreases blood pressure within 10-20 minutes
• Caution: give it time to work, do not re-bolus rapidly
• Eclampsia/pre-eclampsia setting
• Typical dosing is: 5-10 mg IV q 10-20 min prn

Question 15

For hydralazine never exceed this dose

Answer 15

Never exceed 20mg per dose

Question 16

Hydralazine Anesthesia considerations:
Use in caution with
why?

Answer 16

Aortic dissection
Rheumatic Heart Disease
Increased ICP
Elderly 
M multiple cardiovascular risk factors

Question 17

Hydralazine with anesthetic agents

Answer 17

Increased risk of hypotension