What is isosorbide dinitrate, and how does it work (mechanism of action)?
Isosorbide dinitrate is in the class of drugs
called nitrates, and it is used for treating and preventing
angina or
heart pain. Other nitrates include
nitroglycerin
(Nitrostat, Nitroquick, Nitrolingual, Nitro-Dur and others) and
isosorbide mononitrate (Imdur, Ismo, Monoket). Isosorbide dinitrate is
converted in the body to isosorbide mononitrate which is the active chemical.
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”),
and this requires oxygen. 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 dinitrate, improve the flow of blood and oxygen to the
heart and reduce the work that the heart must do by dilating (expanding) 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. In addition, nitrates dilate the arteries that supply the heart
with blood so that the heart receives more blood and oxygen. The FDA approved
isosorbide dinitrate in January 1968.
What brand names are available for isosorbide dinitrate?
Isordil, Isordil Titradose, Dilatrate-SR
Is isosorbide dinitrate available as a generic drug?
Yes
Do I need a prescription for isosorbide dinitrate?
Yes
What are the side effects of isosorbide dinitrate?
Headaches are the most common side effect of isosorbide dinitrate and
usually are dose-related (increase with higher doses). Flushing may occur
because isosorbide dinitrate dilates blood vessels. Isosorbide dinitrate may
cause a drop in blood pressure when rising from a sitting position (orthostatic
hypotension), causing
dizziness,
palpitations, and
weakness. To reduce the risk of these side effects, patients should rise
slowly from a sitting position.
What is the dosage for isosorbide dinitrate?
Isosorbide dinitrate tablets can be taken with or without food. The
sublingual tablets should be dissolved under the tongue and should not be
crushed or chewed. Tolerance (reduced effect after several doses) may develop,
so a drug free period of at least 14 hours is recommended. The recommended doses
of isosorbide dinitrate are:
- Tablets: 5-40 mg 2 or 3 times daily
- Tablets: (sublingual): 2.5-5 mg 15 minutes before activities likely to cause chest pain. For treating chest pain, 2.5 to 5 mg is taken every 5 to 10 minutes.
- Tablets: (extended-release) and capsules (sustained-release): 40-80 mg once or twice daily.
Which drugs or supplements interact with isosorbide dinitrate?
Sildenafil
(Viagra), tadalafil
(Cialis) and
vardenafil (Levitra) increase the blood pressure lowering effects of
isosorbide dinitrate and may cause excessive blood pressure reduction. Patients
taking isosorbide dinitrate should not take sildenafil (Viagra), tadalafil
(Cialis), or vardenafil (Levitra). Severe blood pressure reduction, especially
when changing posture, may occur when isosorbide dinitrate is combined with
calcium channel blockers, for example,
diltiazem
(Cardizem, Tiazac, etc.) and
verapamil (Calan,
Verelan, etc.) which also reduce blood pressure.
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Is isosorbide dinitrate safe to take if I’m pregnant or breastfeeding?
There are no adequate studies of isosorbide dinitrate in
pregnant women.
It is not known if isosorbide dinitrate is excreted in human
breast-milk.
What else should I know about isosorbide dinitrate?
What preparations of isosorbide dinitrate are available?
Tablets (sublingual): 2.5 and 5 mg. Tablets (immediate
release): 5, 10, 20, 30, and 40 mg. Tablets (extended release): 40 mg. Capsules
(sustained release): 40 mg
How should I keep isosorbide dinitrate stored?
Isosorbide dinitrate should be stored at room temperature, 15 C – 30
C (59 F – 86 F).
