- Type of Drug: Calcium channel blocker
- Prescribed for: High blood pressure
Felodipine is a member of one of the most widely prescribed drug categories in the United States. Its once-daily dosage schedule makes Felodipine a natural for treating high blood pressure. It works by blocking the passage of calcium into heart and smooth-muscle tissue, especially the smooth muscle found in arteries. 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. This causes the veins to dilate (open), reducing blood pressure. Also, the amount of oxygen used by the muscles is reduced. Therefore, Felodipine is also useful in the treatment of angina, a type of heart pain related to poor oxygen supply to the heart muscles. Felodipine also dilates the vessels that supply blood to the heart muscles and prevents spasm of these arteries. Felodipine 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 angina pains, abnormal heart rhythms, diseases involving blood vessel spasm (migraine headache, Raynaud’s syndrome), heart failure, and cardiomyopathy.
Felodipine Cautions and Warnings
Felodipine should not be taken if you have had an allergic reaction to it in the past.
On rare occasions, Felodipine may cause very low blood pressure in some people that may lead to stimulation of the heart and rapid heartbeat and can worsen angina pains. This reaction may happen when treatment is first started, when dosage is increased, or if the drug is rapidly withdrawn and can be avoided by gradual dosage reduction.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 in 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.
Patients taking a beta-blocking drug who begin taking Felodipine may develop heart failure or increased angina pain. Angina pain may also increase when your Felodipine dosage is increased.
People with severe liver disease break down Felodipine much more slowly than people with less severe disease or normal livers. Your doctor should take this factor into account when determining your Felodipine dosage.
People taking Felodipine who have had a heart attack and have lung congestion may have worsened heart failure, since this drug can actually slow the force of each heartbeat.
Felodipine Possible Side Effects
Calcium-channel-blocker side effects are generally mild and rarely cause people to stop taking them. Side effects are more common with higher doses and increasing age.
- Most common: swelling in the ankles, feet and legs, dizziness, light-headedness, muscle weakness or cramps, facial flushing, and headache.
- Less common: respiratory infections, cough, tingling in the hands or feet, upset stomach, abdominal’ pains, chest pains, nausea, constipation, diarrhea, heart palpitations, sore throat, runny nose, back pain, and rash.
- Rare: facial swelling and a feeling of warmth, rapid heartbeat, heart attack, very low blood pressure, fainting, angina pains, abnormal heart rhythms, vomiting, dry mouth, stomach gas, anemia, muscle joint and bone pain, depression, anxiety, sleeplessness, irritability and nervousness, daytime tiredness, bronchitis, flu-like symptoms, sinus irritation, breathing difficulty, nosebleeds, sneezing, itching, redness, bruising, sweating, blurred vision, ringing or buzzing in the ears, swelling of the gums, decreased sex drive, loss of sexual ability, painful urination, and frequent and urgent urination.
• Felodipine may increase the amount of beta-blocking drug in the bloodstream. This can lead to 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.
• Felodipine increases the effects of other blood-pressure-lowering drugs. Such drug combinations are often used to treat hypertension.
• Cimetidine and Ranitidine increase the amount of Felodipine in the blood and may account for a slight increase in the drug’s effect.
• Phenytoin and other hydantoin antiseizure medicines, Carbamazepine, and barbiturate sleeping pills and sedatives may decrease the amount of Felodipine in the blood, reducing its effect on your body.
• Erythromycin may increase the side effects of Felodipine by slowing its release from the body.
• Felodipine may increase the effects of Digoxin, Theophylline (for asthma and other respiratory problems), and oral anticoagulant (blood-thinning) drugs.
• Felodipine may also interact with Quinidine (for abnormal heart rhythm) to produce low blood pressure, very slow heart rate, abnormal heart rhythms, and swelling in the arms or legs.
Felodipine Food Interactions
Felodipine can be taken without regard to food or meals. You may take it with food if it upsets your stomach. Taking Felodipine with concentrated grapefruit juice doubles the amount of the drug normally absorbed into the blood; avoid this combination.
5 to 10 mg per day. No patient should take more than 20 mg per day.
Do not stop taking Felodipine abruptly. The dosage should be gradually reduced over a period of time.
Felodipine overdose can cause low blood pressure. If you think you have taken an overdose of Felodipine, call your doctor or go to a hospital emergency room. ALWAYS bring the medicine bottle.
Call your doctor if you develop constipation, nausea, very low blood pressure, difficulty breathing, increased heart pains, dizziness, or light-headedness, or if other side effects are particularly bothersome or persistent.
Swelling of the hands or feet may develop within 2 or 3 weeks of starting Felodipine. The chances of this happening depend both on your age and the Felodipine dosage: It occurs in less than 10 percent of people under age 50 taking 5 mg a day and more than 30 percent of those over age 60 taking 20 mg a day.
Be sure to continue taking your medicine and follow any instructions for diet restriction or other treatments to help maintain lower blood pressure. High blood pressure is a condition with few recognizable symptoms; it may seem to you that you are taking medicine for no good reason. Call your doctor or pharmacist if you have any questions.
Do not break or crush Felodipine tablets.
It is important to maintain good dental hygiene while taking Felodipine and to use extra care when using your toothbrush or dental floss because of the chance that the drug will make you more susceptible to some infections.
If you forget to take a dose of Felodipine, 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 of this medicine.
Felodipine Special Populations
Animal studies with Felodipine have shown that it crosses into the blood circulation of the developing fetus and has caused some birth defects. Women who are or who might become pregnant while taking this drug should not take it without their doctors’ approval. The potential benefit of taking Felodipine must be carefully weighed against its risks.
It is not known if Felodipine passes into breast milk, but it has caused no problems among breast-fed infants. However, you must consider the potential effect on the nursing infant if you breast-feed while taking this medicine.
Older adults, especially those with liver disease, are more sensitive to the effects of this drug because |t takes longer to pass but of their bodies. Follow your doctor’s directions and report any side effects at once.