renato,   Thanks for your question.  Isordil, also known as isosorbide dinitrate, is a medication known as a nitrate.  It dilates, or widens, blood vessels, including the coronary arteries, therefore supplying more blood to the heart muscle.  This is beneficial in situations where there are blockages in the coronary arteries.  It is available in different doses and different forms - oral and sublingual (to be disolved under the tongue).  These forms of isordil are taken three to four times a day.   Nitrates are also available as different drugs.  There is isosorbide mononitrate which is marketed under different names (such as Imdur) which is a long acting form of the nitrate and is taken once a day.  Again, different doses are available.  There are also skin patches that contain nitrates that are release on a continuous basis.  The patches are usually applied daily.  Many doctors prefer the patches be removed at night.  Again, different dosing is also available.    There are a host of other classes of drugs that are used to treat coronary artery disease, and can be used if there is a problem obtaining the isordil.  Your doctor, who knows your situation the best, can assist you in choosing the right medication for you.  So contact your physician for his input in choosing the right medication for your particular situation.  Also, review this website, especially the sections on coronary artery disease and treatment.  Review the different drugs that are used.    I hope this has been helpful.   Martin Cane, M.D.