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Prazosin  (Systemic)

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Brand Names

In the U.S.—

  • Minipress

In Canada—

  • Minipress

Category


Description

Prazosin (PRA-zoe-sin) belongs to the general class of medicines called antihypertensives. It is used to treat high blood pressure (hypertension).

High blood pressure adds to the work load of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain, heart, and kidneys, resulting in a stroke, heart failure, or kidney failure. High blood pressure may also increase the risk of heart attacks. These problems may be less likely to occur if blood pressure is controlled.

Prazosin works by relaxing blood vessels so that blood passes through them more easily. This helps to lower blood pressure.

Prazosin may also be used for other conditions as determined by your doctor.

Prazosin is available only with your doctor's prescription, in the following dosage forms:



Before Using This Medicine

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For prazosin, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to prazosin, doxazosin, or terazosin. Also tell your health care professional if you are allergic to any other substance, such as foods, preservatives, or dyes.

Pregnancy—Limited use of prazosin to control high blood pressure in pregnant women has not shown that prazosin causes birth defects or other problems. Studies in animals given many times the highest recommended human dose of prazosin also have not shown that prazosin causes birth defects. However, in rats given many times the highest recommended human dose, lower birth weights were seen.

Breast-feeding—Prazosin passes into breast milk in small amounts. However, it has not been reported to cause problems in nursing babies.

Children—Studies on this medicine have been done only in adult patients, and there is no specific information comparing use of prazosin in children with use in other age groups.

Older adults—Dizziness, lightheadedness, or fainting (especially when getting up from a lying or sitting position) may be more likely to occur in the elderly, who are more sensitive to the effects of prazosin. In addition, prazosin may reduce tolerance to cold temperatures in elderly patients.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your health care professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.

Other medical problems—The presence of other medical problems may affect the use of prazosin. Make sure you tell your doctor if you have any other medical problems, especially:


Proper Use of This Medicine

For patients taking this medicine for high blood pressure:

To help you remember to take your medicine, try to get into the habit of taking it at the same time each day.

Dosing—

The dose of prazosin will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of prazosin. If your dose is different, do not change it unless your doctor tells you to do so.

The number of capsules or tablets that you take depends on the strength of the medicine.

Missed dose—

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

To store this medicine:


Precautions While Using This Medicine

It is important that your doctor check your progress at regular visits to make sure that this medicine is working properly.

For patients taking this medicine for high blood pressure :

Dizziness, lightheadedness, or sudden fainting may occur after you take this medicine, especially when you get up from a lying or sitting position. These effects are more likely to occur when you take the first dose of this medicine. Taking the first dose at bedtime may prevent problems. However, be especially careful if you need to get up during the night. These effects may also occur with any doses you take after the first dose. Getting up slowly may help lessen this problem. If you feel dizzy, lie down so that you do not faint. Then sit for a few moments before standing to prevent the dizziness from returning.

The dizziness, lightheadedness, or fainting is more likely to occur if you drink alcohol, stand for a long time, exercise, or if the weather is hot. While you are taking this medicine, be careful to limit the amount of alcohol you drink. Also, use extra care during exercise or hot weather or if you must stand for a long time.

Prazosin may cause some people to become drowsy or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy, drowsy, or are not alert. After you have taken several doses of this medicine, these effects should lessen.


Side Effects of This Medicine

Side Effects of This Medicine

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.


Additional Information

Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although these uses are not included in product labeling, prazosin is used in certain patients with the following medical conditions:

For patients taking this medicine for benign enlargement of the prostate:

Other than the above information, there is no additional information relating to proper use, precautions, or side effects for these uses.


Revised: 08/29/1998

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