What is isosorbide mononitrate, and how does it work (mechanism of action)?
Isosorbide mononitrate is in the
class of drugs called nitrates that are used for treating and preventing
angina.
Other nitrates include
nitroglycerin
(Nitrostat, NitroQuick, Nitrolingual, Nitro-Dur and others) and
isosorbide
dinitrate (Isordil Titradose, Dilatrate-SR, Isochron). Nitrates are
vasodilators (dilators of blood vessels). Blood returning from the body in the
veins must be pumped by the heart through the lungs and into the body’s arteries
against the high pressure in the arteries. In order to accomplish this work, the
heart’s muscle must produce and use energy (“fuel”) which requires oxygen
brought to the heart by the blood. The FDA approved isosorbide mononitrate in
December 1991.
Angina pectoris (angina) or “heart pain” is due to an inadequate flow of
blood (and oxygen) to the muscle of the heart. Nitrates, including isosorbide
mononitrate, correct the imbalance between the flow of blood and oxygen to the
heart and the work that the heart must do by dilating the arteries and veins in
the body. Dilation of the veins reduces the amount of blood that returns to the
heart that must be pumped. Dilation of the arteries lowers the pressure in the
arteries against which the heart must pump. As a consequence of both effects,
the heart works less and requires less blood and oxygen.
What brand names are available for isosorbide mononitrate?
Imdur (discontinued brand), Ismo (discontinued brand), Monoket
Is isosorbide mononitrate available as a generic drug?
Yes
Do I need a prescription for isosorbide mononitrate?
Yes
What are the side effects of isosorbide mononitrate?
Headaches are the most common side effect of isosorbide mononitrate and usually are dose related (increase with higher doses). Flushing may occur because isosorbide mononitrate dilates (enlarges) blood vessels. Isosorbide mononitrate may cause a severe drop in blood pressure when rising from a sitting position, causing:
- dizziness,
- palpitations, and
- weakness.
To reduce the risk of low blood pressure, patients should rise slowly from a sitting position.
What is the dosage for isosorbide mononitrate?
The recommended starting dose of isosorbide
mononitrate is 5 to 10 mg of immediate release tablets twice daily. The dose can
be increased to 10 mg twice daily after 2 to 3 days. The target does is 20 mg
twice daily. The two doses should be administered 7 hours apart in order to
avoid tolerance (decreased effect after several doses). The dose for extended
release tablets is 30-240 mg once daily.
Which drugs or supplements interact with isosorbide mononitrate?
Sildenafil
(Viagra), tadalafil
(Cialis), avanafil (Stendra),and
vardenafil
(Levitra) increase the blood pressure lowering effects of isosorbide mononitrate
and may cause
excessive
reductions in blood pressure. Therefore, patients taking isosorbide
mononitrate should not receive sildenafil, tadalafil, avanafil or vardenafil.
Severe reductions in blood pressure, especially when changing posture
(orthostatic hypotension), may occur when isosorbide mononitrate is combined
with
calcium channel blockers [for example,
diltiazem
(Cardizem, Dilacor, Tiazac and several others),
verapamil (Calan,
Verelan, Verelan PM, Isoptin, Isoptin SR, Covera-HS)], which also reduce blood
pressure.
Is isosorbide mononitrate safe to take if I’m pregnant or breastfeeding?
There are no adequate studies of isosorbide
mononitrate in
pregnant women..
It is not known if isosorbide mononitrate
is excreted in
human breast-milk
What else should I know about isosorbide mononitrate?
What preparations of isosorbide mononitrate are available?
Tablets (immediate release): 10, 20 mg.
Tablets (extended release): 30, 60, 120 mg.
How should I keep isosorbide mononitrate stored?
Isosorbide mononitrate should be stored at room
temperature, 15 C – 30 C (59 F – 86 F) in a tight, moisture- proof container.