Drug Detail:Norvasc (Amlodipine [ am-loe-di-peen ])
Drug Class: Calcium channel blocking agents
1. How it works
- Norvasc is a brand (trade) name for amlodipine which may be used to treat high blood pressure or angina.
- Experts believe that Norvasc (amlodipine) works by inhibiting the movement of calcium ions across cardiac (heart) muscle and the smooth muscle lining blood vessel walls. This effect dilates (widens) blood vessels, reducing how hard the heart has to work to pump blood around the body, which reduces blood pressure. This, in turn, reduces the demand for oxygen by the heart which reduces symptoms of angina. Heart rate may also be slightly reduced and exercise capacity is increased.
- Norvasc belongs to the class of medicines known as calcium channel blockers. Norvasc may also be called a calcium channel antagonist.
2. Upsides
- May be used for the treatment of high blood pressure (hypertension), alone or in combination with other agents for high blood pressure.
- May be used as an ongoing treatment to relieve symptoms such as chest pain in people with chronic stable angina, or angina due to coronary artery spasm. Will not relieve acute episodes of angina (other medications such as sublingual nitroglycerin are used for this purpose).
- Available in 2.5mg, 5mg, and 10mg tablets.
- May be preferred over other types of heart medications (for example ACE inhibitors, ARBs) for the treatment of hypertension in African-Americans.
- Can improve a person's tolerance to exercise and keep their blood pressure at acceptable levels during exercise. Heart rate at maximal exercise does not change or is slightly reduced.
- Does not weaken how hard the heart contracts (does not have a negative inotropic effect).
- Lowers blood pressure in both the standing and the sitting position. Does not tend to cause as much of a drop in blood pressure as some other blood pressure-lowering agents when going from a lying down to a standing position. Does not cause reflex tachycardia (a compensatory fast heart rate that often occurs when blood pressure drops).
- Norvasc only needs to be taken once a day.
- Norvasc is available as a generic under the name amlodipine.
3. Downsides
If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:
- Edema (swelling or a collection of fluid) around the lower legs, particularly the ankles, is the main side effect of Norvasc. Shortness of breath, dizziness, fast or irregular heartbeat, flushing, sleepiness, and wheezing have also been reported.
- Appears to have little or no interaction with grapefruit or grapefruit juice products.
- Lower dosages may be needed in people with liver disease.
- May interact with several other drugs including those that are metabolized through hepatic enzymes CYP3A4, cyclosporine, erythromycin, itraconazole, ketoconazole, sildenafil, simvastatin, and immunosuppressants.
- May not be suitable for people with certain preexisting heart conditions, those with low blood pressure (less than 90 mmHg systolic), or those with liver disease.
Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects
4. Tips
- May be taken with or without food.
- Take Norvasc around the same time every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
- The manufacturer states that there is no concern about taking Norvasc with grapefruit or grapefruit juice products.
- Be careful when going from a sitting or lying down position to standing because your blood pressure may drop which may make you dizzy, increasing your likelihood of falls.
- Report to your doctor any signs of dizziness, tiredness, flushing, nausea, indigestion, shortness of breath, excessive weight gain, muscle rigidity or tremors, or edema.
- May cause sleepiness and affect your ability to drive or operate machinery.
- Dial 911 or report to an emergency department if wheezing, facial swelling, chest tightness, cough, or seizures suddenly occur.
- Although Norvasc may be used to prevent ongoing angina symptoms such as chest pain, it does not relieve an acute attack of angina. Most people are also prescribed a medication like sublingual nitroglycerin for this purpose. Talk to your doctor if you do not have a medication that you can take for sudden-onset chest pain.
5. Response and effectiveness
- Peak concentrations occur within 6 to 12 hours of administration. Norvasc's effect lasts for approximately 24 hours.
6. Interactions
Medicines that interact with Norvasc may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with Norvasc. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.
Common medications that may interact with Norvasc include:
- anticonvulsants, such as carbamazepine or fosphenytoin
- antifungal agents, such as itraconazole or ketoconazole
- alfentanil
- amiodarone
- beta-blockers, such as atenolol, labetalol, or metoprolol
- buspirone
- benzodiazepines such as midazolam or triazolam
- carbamazepine
- cimetidine
- cyclosporine
- rifampin
- lovastatin or simvastatin
- quinidine
- NSAIDs, such as diclofenac, ibuprofen, and indomethacin, may decrease the blood pressure-lowering capabilities of Norvasc
- sildenafil
- other medications that inhibit or induce CYP 3A4.
Note that this list is not all-inclusive and includes only common medications that may interact with Norvasc. You should refer to the prescribing information for Norvasc for a complete list of interactions.