Isosorbide dinitrate

A nitrate that eases the heart's workload

Isosorbide dinitrate is an older nitrate medicine. Once swallowed, the body turns it into nitric oxide, which tells the muscle in blood-vessel walls to relax. The veins widen most, so less blood returns to the heart, there is less for it to push against and it needs less oxygen. In angina that is the point: the tightness or pressure in the chest comes on when the heart muscle runs short of oxygen, typically on a brisk walk, a flight of stairs or under stress. Taken regularly, the tablets space those episodes out and make them milder.

What Isordil 10mg is used for

Isordil is stocked for two uses: angina pectoris, and congestive heart failure, where the heart pumps weakly and fluid collects in the legs and lungs. Isordil 10mg tablets are the shop's isosorbide dinitrate product — swallowed, not dissolved under the tongue, and taken to prevent angina rather than to stop an attack that has already begun.

Fitting doses around the day

Each dose lasts only a few hours. Two or three tablets a day is the usual pattern, spaced so that one long stretch passes with no nitrate in the blood. That free stretch stops the vessels getting used to the drug, which would blunt it. Tablets go down with water.

Side effects

Expect a headache in the opening days, sometimes a heavy one; it normally fades. Dizziness on standing, flushing and a quicker pulse are common too, so get up slowly. Some people faint. A rash with a swollen face, lips or throat, or trouble breathing, signals a severe allergic reaction and needs urgent treatment.

Medicines to keep apart from it

Sildenafil, tadalafil and other treatments for erection problems must not be taken with isosorbide dinitrate: together they can drop blood pressure to a dangerous level. Alcohol pushes in the same direction, making a dizzy spell or a faint more likely. Other medicines for high blood pressure can add to the effect as well.