Side Effects of Isordil (isosorbide dinitrate)

Isordil (isosorbide dinitrate) is a nitrate used to treat and prevent angina pectoris or “heart pain.” 

Isordil 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. To accomplish this work, the heart's muscle must produce and use energy, and this requires oxygen. 

Angina 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. 

Common side effects of Isordil include

• headaches,
• flushing, and
• a drop in blood pressure causing dizziness when rising from a sitting position (orthostatic hypotension).

Serious side effects of Isordil include

• lightheadedness like you might pass out,
• worsening angina pain,
• fast or slow heart rate, and
• pounding heartbeats or fluttering in the chest.

Drug interactions of Isordil include sildenafil, tadalafil, and vardenafil, which increase the blood pressure lowering effects of Isordil and may cause excessive blood pressure reduction. 

Severe blood pressure reduction, especially when changing posture, may occur when Isordil is combined with calcium channel blockers which also reduce blood pressure. 

There are no adequate studies of Isordil in pregnant women. 

It is unknown if Isordil is excreted in breast milk.  Consult your doctor before breastfeeding.

• 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.

Adverse reactions to isosorbide dinitrate are generally dose-related, and almost all of these reactions are the result of isosorbide dinitrate’s activity as a vasodilator.

• Headache, which may be severe, is the most commonly reported side effect.
• Headache may be recurrent with each daily dose, especially at higher doses.
• Transient episodes of lightheadedness, occasionally related to blood pressure changes, may also occur.
• Hypotension occurs infrequently, but in some patients it may be severe enough to warrant discontinuation of therapy.
• Syncope, crescendo angina, and rebound hypertension have been reported but are uncommon.
• Extremely rarely, ordinary doses of organic nitrates have caused methemoglobinemia in normalseeming patients. Methemoglobinemia is so infrequent at these doses that further discussion of its diagnosis and treatment is deferred.
• Data are not available to allow estimation of the frequency of adverse reactions during treatment with Isordil Titradose tablets.

To report SUSPECTED ADVERSE REACTIONS, contact Valeant Pharmaceuticals North America LLC at 1-800-321-4576 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

The vasodilating effects of isosorbide dinitrate may be additive with those of other vasodilators. Alcohol, in particular, has been found to exhibit additive effects of this variety.

• Concomitant use of Isordil Titradose with phosphodiesterase inhibitors in any form is contraindicated.
• Concomitant use of Isordil Titradose with riociguat, a soluble guanylate cyclase stimulator, is contraindicated.