Isosorbide (patient information)

Why this medication is prescribed

Isosorbide is used to prevent or treat chest pain (angina). It works by relaxing the blood vessels to the heart, so the blood and oxygen supply to the heart is increased.

This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

How this medication should be used

Isosorbide comes as a regular, sublingual, chewable, and extended-release (long-acting) tablet and extended-release (long-acting) capsule to be taken by mouth. The tablet usually is taken every 6 hours. The extended-release tablet usually is taken one or two times a day. The extended-release capsule usually is taken every 8-12 hours. Do not crush, chew, or divide the extended-release tablets or capsules. The sublingual or chewable tablet is used as needed to relieve chest pain that has already started or to prevent pain before activities known to provoke attacks (e.g., climbing stairs, sexual activity, heavy exercise, or being outside in cold weather). The chewable tablet also may be used every 2-3 hours to prevent chest pain. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take isosorbide exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Isosorbide controls chest pain but does not cure it. Continue to take isosorbide even if you feel well. Do not stop taking isosorbide without talking to your doctor. Stopping the drug abruptly may cause chest pain.

Isosorbide can lose its effectiveness when used for a long time. This effect is called tolerance. If your angina attacks happen more often, last longer, or are more severe, call your doctor.

If you are using isosorbide sublingual or chewable tablets for acute chest pain, you should carry the tablets with you at all times. If you are taking isosorbide and your chest pain is not relieved within 5-10 minutes, take another dose. Call for emergency assistance or go to a hospital emergency department if pain persists after you have taken three tablets (at 5-10-minute intervals) and 15-30 minutes have passed.

When an attack occurs, sit down. If you use chewable tablets, chew a tablet thoroughly and swallow it. To use the sublingual tablets, place a tablet under your tongue or between your cheek and gum and allow it to dissolve. Do not swallow the tablet. Try not to swallow saliva too often until the tablet dissolves.

Other uses for this medicine

Isosorbide tablets are also used with other drugs to treat congestive heart failure. Talk to your doctor about the possible risks of using this drug for your condition.

Special precautions

Before taking isosorbide:

• tell your doctor and pharmacist if you are allergic to isosorbide; nitroglycerin tablets, patches, or ointment; or any other drugs.
• tell your doctor and pharmacist what prescription and nonprescription medications you are taking, especially aspirin; beta blockers such as atenolol (Tenormin), carteolol (Cartrol), labetalol (Trandate, Normodyne), metoprolol (Lopressor), nadolol (Corgard), propranolol (Inderal), sotalol (Betapace), and timolol (Blocadren); calcium channel blockers such as amlodipine (Norvasc), diltiazem (Cardizem), felodipine (Plendil), isradipine (DynaCirc), nifedipine (Procardia), and verapamil (Calan, Isoptin); dihydroergotamine (D.H.E. 45); sildenafil (Viagra); tadalafil (Cialis); vardenafil (Levitra); and vitamins.
• tell your doctor if you have or have ever had low red blood cell counts (anemia), glaucoma, or recent head trauma.
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking isosorbide, call your doctor.
• if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking isosorbide.
• you should know that this drug may make you drowsy or dizzy. Do not drive a car or operate machinery until you know how it affects you.
• tell your doctor if you consume large amounts of alcohol regularly and ask about the safe use of alcoholic beverages while you are taking isosorbide. Alcohol can make the side effects from isosorbide worse.

Special dietary instructions

Take isosorbide tablets on an empty stomach (at least 1 hour before or 2 hours after meals) with a full glass of water.

What to do if you forget a dose

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

Side Effects

Minor Side Effects

Side effects from isosorbide are common. Tell your doctor if any of these symptoms are severe or do not go away:

• headache
• rash
• dizziness
• upset stomach
• headache
• flushing (feeling of warmth)

Severe Side Effects

If you experience any of the following symptoms, call your doctor immediately:

• blurred vision
• dry mouth
• chest pain
• fainting

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online [at http://www.fda.gov/MedWatch/report.htm] or by phone [1-800-332-1088].

Storage conditions needed for this medication

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Keep sublingual and chewable tablets in the original container. Do not open a container of sublingual or chewable isosorbide until you need a dose. Do not use tablets that are more than 12 months old. Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

In case of emergency/overdose

In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

Other information

Keep all appointments with your doctor and the laboratory.

Isosorbide regular and extended-release tablets or capsules should not be used for acute angina attacks. Continue to use isosorbide sublingual or chewable tablets to relieve chest pain that has already started.

If headache continues, ask your doctor if you may take acetaminophen. Your isosorbide dose may need to be adjusted. Do not take aspirin or any other medication for headache while using isosorbide unless you doctor tells you to.

The tablets may cause a sweet, tingling sensation when placed under your tongue. This sensation is not an accurate indicator of drug strength; the absence of a tingling sensation does not mean that the drug is not working.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

Brand names

• Dilatrate®-SR
• Imdur®
• Ismo®
• Isordil®
• Isordil® Titradose®
• Monoket®

Other names

• ISDN