Isosorbide dinitrate belongs to the class of medications called anti-anginals. It is used to prevent chest pain associated with angina. It works by relaxing blood vessels and increasing the blood and oxygen supply to the heart. Isosorbide dinitrate may reduce the number, length, and severity of angina attacks. Tolerance for exercise may be increased and the need for fast-acting nitroglycerin (tablets and spray) may be reduced.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

Oral tablets: The recommended dose of isosorbide oral tablets for long-term prevention of angina is 5 mg to 30 mg taken 4 times daily, leaving a period of time called the nitrate-free period (as discussed with your doctor) where the body is relatively free of the medication. For example, the medication may be taken at 8 am, 12 pm, 4 pm, and 8 pm. This schedule allows the medication to keep working effectively as it prevents your body from getting too used to its effects.

Sublingual tablets (tablets dissolve in 20 seconds under the tongue): Isosorbide sublingual (under the tongue) tablets are dissolved under the tongue to prevent an angina attack. Dissolve 1 or 2 tablets (5 mg to 10 mg) under the tongue, between the cheek and gum, or between the lip and gum every 2 to 4 hours. An extra dose of 5 mg to 10 mg may be taken before stressful situations that are likely to cause an angina attack. Do not eat, drink, smoke, or chew tobacco while the tablet is dissolving. Talk to your doctor about the dose and nitrate-free period that are right for you.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by the doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is close to the time of your next scheduled dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Sublingual tablets

5 mg
Each pink, round, flat-faced sublingual tablet engraved "5" on one side contains 5 mg of isosorbide dinitrate. Nonmedicinal ingredients: lactose monohydrate, microcrystalline cellulose, croscarmellose sodium, 6 magnesium stearate, colloidal silicon dioxide, and D&C Red No. 30 Aluminum Lake.

Tablets

10 mg
Each white, round, flat-faced, scored tablet engraved "10" on one side contains 10 mg of isosorbide dinitrate. Nonmedicinal ingredients: lactose monohydrate, microcrystalline cellulose, croscarmellose sodium, and 6 magnesium stearate.

30 mg
Each white, round, flat-faced, scored tablet engraved "30" on one side contains 30 mg of isosorbide dinitrate. Nonmedicinal ingredients: lactose monohydrate, microcrystalline cellulose, croscarmellose sodium, 6 magnesium stearate, and colloidal silicon dioxide.

Do not take isosorbide dinitrate if you:

• are allergic to isosorbide or any ingredients of the medication
• have or are at risk for a heart condition known as cardiogenic shock (e.g., after a heart attack)
• are taking a type of medication known as PDE-5 inhibitors, which are used for erectile dysfunction; e.g., sildenafil (Viagra®), tadalafil (Cialis®), vardenafil (Levitra®)

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• dizziness or lightheadedness, especially when getting up from a lying or sitting position
• fast pulse
• flushing of face and neck
• headache
• nausea
• restlessness
• vomiting
• weakness

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• blurred vision
• fainting
• headache (severe or prolonged)
• skin rash
• sweating

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin taking a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should take this medication.

Medical conditions: If you have low blood pressure, glaucoma, or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Low Blood Pressure: When isosorbide dinitrate relaxes the blood vessels, the blood vessels become wider, allowing blood to flow more easily. This can cause blood pressure to decrease. While this usually isn't a problem, some people experience dizziness, headache, or fainting, particularly when rising from a seated or lying position. If you have low blood pressure or experience these symptoms when you are taking isosorbide dinitrate, talk to your doctor.

Tolerance: The body can get used to the effects of isosorbide dinitrate (develop a tolerance), especially if the medication is taken throughout the day without a "nitrate-free period" (a 10 to 12-hour break from the medication). If you find that your symptoms of angina are getting worse or lasting longer, call your doctor.

Withdrawal: Stopping this medication suddenly may occasionally aggravate chest pain or other symptoms of angina. To avoid possible withdrawal effects, isosorbide dinitrate should be gradually reduced and not stopped suddenly. Talk to your doctor about how to stop the medication safely.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if isosorbide dinitrate passes into breast milk. If you are breast-feeding and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

Seniors: Seniors may be more likely to experience dizziness or lightheadedness taking isosorbide dinitrate.

There may be an interaction between isosorbide dinitrate and any of the following:

• alcohol
• aldesleukin
• aliskiren
• alpha blockers (e.g., alfuzosin, doxazosin, tamsulosin)
• alpha agonists (e.g., clonidine, methyldopa)
• amiodarone
• angiotensin converting enzyme inhibitors (ACEIs; captopril, enalapril, ramipril)
• angiotensin receptor blockers (ARBs; e.g., candesartan, irbesartan, losartan)
• second generation anti-psychotics (e.g., clozapine, olanzapine, quetiapine, risperidone)
• barbiturates (e.g., butalbital, phenobarbital)
• beta-adrenergic blockers (e.g., atenolol, propranolol, sotalol)
• bortezomib
• brimonidine
• bromocriptine
• calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
• dapsone
• diuretics (water pills; e.g., furosemide, hydrochlorothiazide, triamterene)
• duloxetine
• general anesthetics (medications used to put people to sleep before surgery)
• hydralazine
• levodopa
• lidocaine
• monoamine oxidase inhibitors (e.g., phenelzine, rasagiline, selegiline, tranylcypromine)
• morphine
• obinutuzumab
• other nitrates (e.g., nitroglycerin, isosorbide mononitrate)
• pentoxifylline
• medications for erectile dysfunction called phosphodiesterase 5 inhibitors (PDE-5 inhibitors; e.g., sildenafil, tadalafil, vardenafil)
• pramipexole
• primidone
• riociguat
• ropinirole
• rotigotine
• rosiglitazone
• sacubitril
• sodium phosphates
• tizanidine
• tretinoin
• tricyclic antidepressants (e.g., clomipramine, imipramine)

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.