Rinfocan- Prescription Drug Information for Canadians
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(generic name)
BRAND NAMES
Plendil, Renedil
TYPE OF DRUG
Calcium channel blocker.
PRESCRIBED FOR
High blood pressure.
Other calcium channel blockers have also been prescribed to treat angina pectoris,
Prinzmetal's angina, asthma, to prevent migraine headaches and other conditions.
GENERAL INFORMATION
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,
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 (opens) 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 affect on calcium in the blood.
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.
This may lead to stimulation of the heart and rapid heartbeat and can worsen angina
pains in some people.
Patients taking a beta-blocking drug who begin taking Felodipine may develop heart
failure or increased angina pain. Angina pain may also increase at the time 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.
PREGNANCY/BREAST-FEEDING
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 might
become pregnant while taking this drug should not take it without their doctors'
approval. The potential risk of taking Felodipine must be carefully weighed against the
benefit it might produce.
It is not known if Felodipine passes into breast milk, but it has caused no problems
among breast-fed infants. You must consider the potential effect on the nursing infant
if you breast-feed while taking this medicine.
SENIORS
Older adults, especially those with liver disease, are more sensitive to the effects of
this drug because it takes longer to pass out of their bodies. Follow your doctor's
directions and report any side effects at once.
POSSIBLE SIDE EFFECTS
The most common side effects are swelling in the feet and legs and headache. Side
effects are more common with higher doses and increasing age.
Less common side effects include flushing, dizziness, respiratory infections, muscle
weakness and cramps, 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 side effects include 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.
DRUG INTERACTIONS
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 blood-pressure effects of other blood-pressure-lowering
drugs. 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.
Felodipine may increase the effects of Digoxin.
Other calcium channel blockers can increase the effects of Theophylline (for asthma
and other respiratory problems) and oral anticoagulant (blood-thinning) drugs. They
can 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, as a member of the same drug class, may interact in the same way.
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 results in
twice as much as normal of the drug being absorbed into the blood; avoid the
combination.
USUAL DOSE
5 to 10 milligrams per day. No patient should take more than 20 milligrams per day.
Do not stop taking Felodipine abruptly. The dosage should be gradually reduced over
a period of time.
OVERDOSAGE
Overdose of Felodipine 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.
SPECIAL INFORMATION
Call your doctor if you develop constipation, nausea, very low blood pressure,
swelling in the hands or feet, difficulty breathing, increased heart pains, dizziness, or
light-headedness or if other side effects are particularly bothersome or persistent.
Be sure to continue taking your medicine and follow any instructions for diet
restriction or other treatments to help maintain a 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.
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