Isradipine (DynaCirc) for High blood pressure

  • Type of Drug: Calcium channel blocker.
  • Prescribed for: High blood pressure. It has also been prescribed to treat chronic stable angina pectoris.
  • Brand Name: DynaCirc.

General Information of Isradipine

Isradipine is one of many calcium channel blockers available in the United States. It works by blocking the passage of calcium into smooth muscle. Since calcium is an ‘essential factor in muscle contraction, any drug that affects calcium in this way will interfere with the contraction of these muscles. When this happens, several things can result. Blood vessels will dilate (widen) because the muscles that normally keep them narrowed are not contracting, and the amount of oxygen used by heart muscle may also be reduced. Therefore, Isradipine dilates (opens) the arteries that carry blood and prevents spasm of these arteries, Isradipine is also used in the treatment of angina, a type of heart pain related to poor oxygen supply to the heart muscles. Isradipine affects the movement of calcium only into muscle cells. It does not have any effect on calcium in the blood. Other calcium channel blockers are used for abnormal heart rhythms, diseases involving blood vessel spasm (migraine headache, Raynaud’s syndrome), heart failure, and cardiomyopathy.

Cautions and Warnings

Do not take this drug if you have had an allergic reaction to it. Use Isradipine with caution if you have heart failure, since the drug can worsen the condition. Abruptly stopping this medication can cause increased chest pain. If you must stop, the drug dose should be gradually reduced.

On rare occasions, Isradipine may cause very low blood pressure in some people. This may lead to stimulation of the heart and rapid heartbeat and can worsen angina pains in some people.

Isradipine may cause angina pain when treatment is first started, when dosage is increased, or if the drug is rapidly withdrawn. This can be avoided by gradual dosage reduction.

Studies have shown, that people taking calcium channel blockers (usually those taken several times a day, not those taken only once daily) have a greater chance of having a heart attack than people taking beta blockers or other medicines for the same purposes. Discuss this with your doctor to be sure you are receiving the best possible treatment.

Isradipine can slow heart rate, which increases the possibility of worsening heart failure.
People with severe liver disease break down Isradipine much more slowly than people with less severe disease or normal livers. Your doctor should take this factor into account when determining your Isradipine dosage.

Possible Side Effects of Isradipine

Isradipine side effects are generally mild and self-limiting.

  • Most common: headache.
  • Less common: low blood pressure, chest pain, swelling of the. legs, ankles or feet, rapid heartbeat, dizziness, diarrhea, a feeling of warmth, nausea, lightheadedness, fatigue and lethargy, itching, rash, flushing, changes in certain blood-cell components, and headache.
  • Rare: fainting, heart failure, heart attack, abnormal heart rhythms, stroke, numbness, drowsiness, nervousness, depression, paranoia, memory loss, hallucinations, psychoses, visual disturbances, sleeplessness, tingling in the hands or feet, heart palpitations, constipation, stomach upset and cramps, vomiting, dry mouth, frequent urination (especially at night), sweating, reduced sex drive or poor sexual performance, leg and foot cramps, muscle cramps and inflammation, joint pains, sore throat, and cough. Isradipine can cause increases in certain blood enzyme tests.

Drug Interactions

  • Isradipine may interact with beta-blocking drugs to cause heart failure, very low blood pressure, or an increased incidence of angina pain. However, in many cases these drugs have been taken together with no problem.
  • Taking Isradipine and Fentanyl (a narcotic pain reliever) together can result in very low blood pressure.

Food Interactions

Taking Isradipine with food has a minor effect on the absorption of the drug. You may take it with food if it upsets your stomach. Avoid drinking grapefruit juice if you are taking this medicine.

Usual Dose of Isradipine

5 to 20 mg per day in 2 doses.
Do not stop taking the drug abruptly. The dosage should be gradually reduced over a period of time.


Overdose of Isradipine cart cause nausea, dizziness, weakness, drowsiness, confusion and slurred speech, very low blood pressure, reduced heart efficiency, and unusual heart rhythms. Victims of an Isradipine overdose should be taken to a hospital emergency room for treatment. ALWAYS bring the medicine bottle with you.

Special Information

Call your doctor if you develop swelling in the arms or legs, difficulty breathing, abnormal heartbeat, increased heart pains, dizziness, constipation, nausea, light-headedness, or very low blood pressure.

If you forget to take a dose of Isradipine, take it as soon as you remember. If it is almost time for your next regularly scheduled dose, skip the forgotten dose and continue with your regular schedule. Do not take a double dose.

Isradipine Special Populations

Laboratory studies found Isradipine to affect the development of animal fetuses in laboratory studies. It has not been found to cause human birth defects. Nevertheless, pregnant women, or those who might become pregnant while taking this drug, should not take Isradipine without their doctor’s approval. When the drug is considered essential by your doctor, the potential benefit of taking the medicine must be carefully weighed against its risk.
It is not known if Isradipine passes into breast milk. Women who must take Isradipine should consider the possible effect of the drug on their infants before breast-feeding.

Older adults may actually absorb more Isradipine than younger adults and may release the drug more slowly from their bodies. Follow your doctor’s directions and report any side effects at once.