Smooth Muscle Vasoactive Drugs: Nitrates

Question 1

Nitrates are

Answer 1

antianginal therapy

Question 2

nitrates are metabolized and release

Answer 2

nitric oxide

Question 3

nitric oxide causes an increase in

Answer 3

cGMP in vascular smooth muscle cells

Question 4

nitric oxide causes an increase in cGMP in vascular smooth muscle cells which causes

Answer 4

increased cGMP causes myosin light chain dephosphorylation, preventing its interaction with actin (vascular smooth muscle RELAXATION)

Question 5

nitrates cause

Answer 5

venous dilation and increased venous capacitance (PRIMARY effect)

Question 6

only at higher doses do nitrates start to

Answer 6

dilate large arteries and arterioles (even large coronary arteries!) (nitrates are PRIMARILY VENODILATORS)

Question 7

Nitrates decrease preload by

Answer 7

promoting venodilation and increasing venous capacitance

Question 8

nitrates treat

Answer 8

chronic stable angina

Question 9

nitrates relieve symptoms of angina by

Answer 9

nitrates relieve symptoms of angina by reducing cardiac oxygen demand (venodilation → decreased venous return → decreased preload → decreased LVEDP and reduced wall stress)

Question 10

sublingual administration of nitroglycerine avoids

Answer 10

sublingual administration of nitroglycerine avoids first pass metabolism (for acute symptom relief)

Question 11

oral nitrate preparations have

Answer 11

a longer duration of action

Question 12

Oral nitrates

Answer 12

1. isosorbide mononitrate

2. isosorbide dinitrate

Question 13

oral nitrate preparations require

Answer 13

oral nitrate preparations require larger dosing (nitroglycerine and isosorbide dinitrate undergo first pass metabolism in the liver)

Question 14

nitrates treat

Answer 14

Prinzmetal angina (coronary vasodilatory action)

Question 15

nitrates are useful in

Answer 15

nitrates are useful in acute coronary syndrome (ACS) (decrease preload → decrease cardiac workload and oxygen requirements)

Question 16

nitrates should be avoided in

Answer 16

nitrates should be avoided in right sided MI (decreasing RV preload can severely drop blood pressure)

Question 17

IV nitroglycerine can be used in

Answer 17

IV nitroglycerine can be used in hypertensive emergency (or nitroprusside)

Question 18

nitrates can be used to treat

Answer 18

acute pulmonary edema (e.g. in acute heart failure) by decreasing preload and LVEDP

Question 19

nitrates can cause

Answer 19

1. orthostatic hypotension
2. throbbing headaches and flushing
3. methhemoglobinemia

Question 20

nitrate induced hypotension causes

Answer 20

reflex tachycardia

Question 21

beta blockers help prevent

Answer 21

reflex sympathetic activation

Question 22

Avoid nitrate tolerance with

Answer 22

avoid tolerance with daily nitrate free intervals

Question 23

workplace exposure to nitrates causes

Answer 23

workplace exposure to nitrates causes drug TOLERANCE (tachyphylaxis, or decreased effect over time) → tolerance diminishes over the weekend -→ headache and dizziness recur on Monday with re-exposure

Question 24

patients on PDE-5 inhibitors

Answer 24

patients on PDE-5 inhibitors (e.g. sildenafil) should avoid nitrate therapy for 24 hrs

Question 25

nitrates are contraindicated with

Answer 25

nitrates are contraindicated with hypertrophic obstructive cardiomyopathy (HOCM)