Minipress

DRUG DESCRIPTION

MINIPRESS® (prazosin hydrochloride), a quinazoline derivative, is the first of a new chemical class of antihypertensives. It is the hydrochloride salt of 1-(4-amino-6,7-dimethoxy- 2-quinazolinyl)-4-(2-furoyl) piperazine and its structural formula is:

MINIPRESS® (prazosin hydrochloride) structural formula illustration

Molecular formula C19H21N5O4.HCl

It is a white, crystalline substance, slightly soluble in water and isotonic saline, and has a molecular weight of 419.87. Each 1 mg capsule of MINIPRESS (prazosin hcl) for oral use contains drug equivalent to 1 mg free base.

Inert ingredients in the formulations are: hard gelatin capsules (which may contain Blue 1, Red 3, Red 28, Red 40, and other inert ingredients); magnesium stearate; sodium lauryl sulfate; starch; sucrose.

What are the possible side effects of prazosin (Minipress)?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have any of these serious side effects:

  • fast or pounding heartbeats;
  • feeling like you might pass out;
  • feeling short of breath;
  • swelling in your hands, ankles, or feet; or
  • penis erection that is painful or lasts 4 hours or longer.

Less serious side effects may...

Read All Potential Side Effects and See Pictures of Minipress »

What are the precautions when taking prazosin hcl (Minipress)?

Before taking prazosin, tell your doctor or pharmacist if you are allergic to it; or to other alpha blockers (such as doxazosin, terazosin); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: heart problems (such as low blood pressure), kidney disease, uncontrolled attacks of deep sleep (narcolepsy), prostate cancer.

This drug may make you dizzy or drowsy or cause blurred vision. Do not drive, use machinery, or do any activity that requires alertness or clear vision until you are sure you can perform such activities safely. Do not drive or participate...

Read All Potential Precautions of Minipress »


Minipress Consumer (continued)

SIDE EFFECTS: Headache, drowsiness, tiredness, weakness, blurred vision, nausea, vomiting, diarrhea, or constipation may occur as your body adjusts to the medication. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.

Lightheadedness or dizziness upon standing may also occur, especially after the first dose and shortly after taking a dose of the drug during the first week of treatment. To reduce the risk of dizziness and fainting, get up slowly when rising from a seated or lying position. If dizziness occurs, sit or lie down immediately. Your dose may need to be adjusted.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor immediately if any of these unlikely but serious side effects occur: pounding heartbeat, fainting, frequent urination, mental/mood changes (such as depression), swelling of the feet/ankles.

For males, in the very unlikely event you have a painful, prolonged erection (lasting more than 4 hours), stop using this drug and seek immediate medical attention, or permanent problems could occur.

A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

PRECAUTIONS: Before taking prazosin, tell your doctor or pharmacist if you are allergic to it; or to other alpha blockers (such as doxazosin, terazosin); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: heart problems (such as low blood pressure), kidney disease, uncontrolled attacks of deep sleep (narcolepsy), prostate cancer.

This drug may make you dizzy or drowsy or cause blurred vision. Do not drive, use machinery, or do any activity that requires alertness or clear vision until you are sure you can perform such activities safely. Do not drive or participate in hazardous activities for 24 hours after your first dose, any increase in your dosage, or restarting treatment. If your doctor prescribes any additional blood pressure drugs, avoid driving and hazardous activities for 24 hours after your first dose of the new medication. Limit alcoholic beverages.

To reduce the risk of dizziness and fainting, be careful when standing for long periods. Avoid getting overheated during exercise and hot weather. When first starting this drug, avoid situations where you may be injured if you faint.

Before having surgery (including cataract eye surgery), tell your doctor or dentist that you are taking this medication and about all the products you use (including other prescription drugs, nonprescription drugs, and herbal products).

Older adults may be more sensitive to the side effects of this drug, especially dizziness and fainting.

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

Prazosin passes into breast milk. Consult your doctor before breast-feeding.


Minipress Patient Information Including Side Effects

Brand Names: Minipress

Generic Name: prazosin (Pronunciation: PRA zoe sin)

  • What is prazosin (Minipress)?
  • What are the possible side effects of prazosin (Minipress)?
  • What is the most important information I should know about prazosin (Minipress)?
  • What should I discuss with my healthcare provider before taking prazosin (Minipress)?
  • How should I take prazosin (Minipress)?
  • What happens if I miss a dose (Minipress)?
  • What happens if I overdose (Minipress)?
  • What should I avoid while taking prazosin (Minipress)?
  • What other drugs will affect prazosin (Minipress)?
  • Where can I get more information?

What is prazosin (Minipress)?

Prazosin is in a group of drugs called alpha-adrenergic blockers. Prazosin causes the blood vessels (veins and arteries) to relax and expand, improving blood flow. Prazosin also relaxes muscles in the prostate and bladder neck, making it easier to urinate.

Prazosin is used to treat hypertension (high blood pressure).

Prazosin may also be used for other purposes not listed in this medication guide.

What are the possible side effects of prazosin (Minipress)?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have any of these serious side effects:

  • fast or pounding heartbeats;
  • feeling like you might pass out;
  • feeling short of breath;
  • swelling in your hands, ankles, or feet; or
  • penis erection that is painful or lasts 4 hours or longer.

Less serious side effects may include:

  • drowsiness, dizziness, spinning sensation;
  • weakness, tired feeling;
  • headache;
  • nausea, vomiting, constipation, diarrhea;
  • numbness or tingly feeling;
  • stuffy nose, dry mouth; or
  • blurred vision.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What is the most important information I should know about prazosin (Minipress)?

You should not use this medication if you are allergic to prazosin.

Prazosin may cause dizziness or fainting, especially when you first start taking it or when you start taking it again. Be careful if you drive or do anything that requires you to be alert. Avoid standing for long periods of time or becoming overheated during exercise and in hot weather. Avoid getting up too fast from a sitting or lying position, or you may feel dizzy.

Call your doctor if you have severe dizziness or feel like you might pass out.

Some things can cause your blood pressure to get too low. This includes vomiting, diarrhea, heavy sweating, heart disease, dialysis, a low-salt diet, or taking other diuretics (water pills). Tell your doctor if you have a prolonged illness that causes diarrhea or vomiting.

Avoid drinking alcohol. It can increase some of the side effects of prazosin.

To be sure prazosin is helping your condition, your blood pressure will need to be checked on a regular basis. Your doctor will also need to check your progress. Do not miss any scheduled appointments.

Keep using this medicine as directed, even if you feel well. High blood pressure often has no symptoms. You may need to use blood pressure medication for the rest of your life.

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