prazosin (Rx)

Brand and Other Names:Minipress, Prazin, more...Prazo
  • Print

Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

capsule

  • 1mg
  • 2mg
  • 5mg

Hypertension

Initial: 1 mg PO q8-12hr

Maintenance: 6-15 mg/day divided 2 or 3 times daily; alternatively, 1-5 mg PO BID; may increase dose to 20 mg/day in divided doses; some patients may benefit from up to 40 mg/day in divided doses

PTSD-Related Nightmares & Sleep Disruption (Off-label)

Initial: 1 mg PO qHS

Maintenance: 1 mg PO qHS initially; may increase dose to 2 mg qHS; adjust dose based on response and tolerability in 1-2 mg increments q7days; not to exceed 15 mg/day

Benign Prostate Hypertrophy (Off-label)

Initial: 0.5 mg PO q12hr

Maintenance: 2 mg PO q12hr

Raynaud Phenomenon (Off-label)

0.5-1 mg PO qDay (HS) or 0.5 mg PO BID; adjust dose based on response and tolerability up to 12 mg/day divided BID/TID

Administration

Give first dose and subsequent increases at bedtime to avoid syncope

Okay with food

Dosage Forms & Strengths

capsule

  • 1mg
  • 2mg
  • 5mg

Hypertension (Off-label)

Initial: 0.05-0.1 mg/kg/day PO divided q8hr  

Titrate to 0.5 mg/kg/day; not to exceed 20 mg/day

Administration

Okay with food

Next:

Interactions

Interaction Checker

and prazosin

No Results

     activity indicator 
    No Interactions Found
    Interactions Found

    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

            All Interactions Sort By:
             activity indicator 
            Due to system maintenance, the drug interactions feature you are attempting to access is temporarily unavailable. Please try again later.
            Previous
            Next:

            Adverse Effects

            1-10%

            Dizziness (10%)

            Drowsiness (8%)

            Headache (8%)

            Weakness (7%)

            Asthenia (6.5%)

            Nausea (5%)

            Palpitation (5%)

            Frequency Not Defined (Selected)

            Edema

            Orthostatic hypotension

            Syncope

            Fever

            Rash

            Abdominal discomfort/pain

            Diarrhea

            Vomiting

            Abnormal liver function tests

            Impotence

            Pancreatitis

            Urinary incontinence

            Previous
            Next:

            Warnings

            Contraindications

            Hypersensitivity

            Cautions

            Risk of syncope; has no relation to plasma prazosin concentration; if syncope occurs, place patient in the recumbent position and treat supportively as necessary

            Discontinue if angina symptoms occur or worsen

            May cause CNS depression, which may impair physical or internal abilities; use caution when performing tasks that require mental alertness

            May impair ability to drive/perform hazardous tasks due to dizziness

            History of narcolepsy - May exacerbate

            Cataract surgery - Linked to intraoperative floppy iris syndrome

            Concomitant administration with PDE-5 inhibitor (eg, sildenafil) can result in additive blood pressure-lowering effects and symptomatic hypotension; initiate PDE-5 inhibitor therapy at lowest dose

            First dose effect may occur, causing a sudden and drastic fall in blood pressure after administration of the first dose.

            May exacerbate heart failure

            Prolonged erections and priapism reported with alpha-1 blockers including prazosin in post marketing experience; if erection persists > 4 hours, seek immediate medical assistance

            May cause significant orthostatic hypotension and syncope with sudden loss of consciousness, especially 30-90 min of first dose; may also occur if therapy interrupted for a few days, if dosage rapidly increased or if another antihypertensive drug, like a beta-blocker or vasodilator, or a phosphodiesterase 5 inhibitor is introduced

            Prostatic carcinoma should be ruled out before initiating therapy

            Geriatric considerations

            • Avoid use for hypertension; high risk of orthostatic hypotension (Beers criteria)
            • May cause significant orthostatic hypotension and syncope; consider lower initial dose; titrate to response
            • Adverse effects such as dry mouth and urinary complications can be bothersome in the elderly
            Previous
            Next:

            Pregnancy & Lactation

            Pregnancy category: C

            Lactation: Excreted in breast milk; use caution

            Pregnancy Categories

            A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA: Information not available.

            Previous
            Next:

            Pharmacology

            Mechanism of Action

            Alpha-1 blocker inhibits postsynaptic alpha-adrenergic receptors, causing arterial and venous dilation and a subsequent decrease in blood pressure

            Absorption

            Bioavailability: 43-82%

            Onset: ~2 hr

            Duration: 10-24 hr

            Peak effect: 2-4 hr

            Peak plasma time: 2-3 hr

            Distribution

            Protein bound: 97%

            Metabolism

            Hepatic metabolization (extensive)

            Elimination

            Half-life elimination: 2-3 hr

            Excretion: Urine (6-10%); rest in feces (via bile)

            Previous
            Next:

            Images

            BRAND FORM. UNIT PRICE PILL IMAGE
            prazosin oral
            -
            5 mg capsule
            prazosin oral
            -
            1 mg capsule
            prazosin oral
            -
            2 mg capsule
            prazosin oral
            -
            1 mg capsule
            prazosin oral
            -
            2 mg capsule
            prazosin oral
            -
            2 mg capsule
            prazosin oral
            -
            5 mg capsule
            prazosin oral
            -
            5 mg capsule
            prazosin oral
            -
            2 mg capsule
            prazosin oral
            -
            1 mg capsule
            prazosin oral
            -
            2 mg capsule
            prazosin oral
            -
            2 mg capsule
            prazosin oral
            -
            1 mg capsule
            prazosin oral
            -
            1 mg capsule
            prazosin oral
            -
            5 mg capsule
            prazosin oral
            -
            5 mg capsule
            prazosin oral
            -
            2 mg capsule
            Minipress oral
            -
            2 mg capsule
            Minipress oral
            -
            1 mg capsule
            Minipress oral
            -
            5 mg capsule

            Copyright © 2010 First DataBank, Inc.

            Previous
            Next:

            Patient Handout

            Patient Education
            prazosin oral

            PRAZOSIN - ORAL

            (PRAZ-oh-sin)

            COMMON BRAND NAME(S): Minipress

            USES: Prazosin is used with or without other medications to treat high blood pressure. Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems.Prazosin belongs to a class of medications called alpha blockers. It works by relaxing and widening blood vessels so blood can flow more easily.

            HOW TO USE: Take this medication by mouth with or without food as directed by your doctor, usually two or three times daily. If stomach upset occurs, take with food or milk. The dosage is based on your age, medical condition and response to therapy.Prazosin can occasionally cause sudden fainting after the first dose and anytime that your dose is increased. To reduce your risk of fainting, the first dose prescribed by your doctor will be the smallest dose available. You should take this first dose as you are going to bed. This will decrease the possibility of fainting. Your dose may be gradually increased. Take your first new dose at bedtime when your dose is increased unless directed otherwise by your doctor.Use this medication regularly in order to get the most benefit from it. To help you remember, take it at the same time(s) each day. If you are taking this medication for high blood pressure, keep taking it even if you feel well. Most people with high blood pressure do not feel sick. It may take up to several weeks before the full benefit of this drug takes effect.Do not stop taking this medication without first consulting your doctor. Some conditions may become worse when the drug is abruptly stopped. Your dose may need to be gradually decreased.Tell your doctor if your condition worsens (such as your routine blood pressure readings increase).

            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 last or get worse, 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 right away. Your dose may need to be adjusted.Remember that this medication has been prescribed because your doctor 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 right away if you have any serious side effects, including: pounding heartbeat, fainting, frequent urination, mental/mood changes (such as depression), swelling of the feet/ankles.Rarely, males may have a painful or prolonged erection lasting 4 or more hours. If this occurs, stop using this drug and get medical help right away, or permanent problems could occur.A very serious allergic reaction to this drug is rare. However, get medical help right away 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 or at www.fda.gov/medwatch.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, certain eye problems (cataracts, glaucoma).This drug may make you dizzy or drowsy or blur your vision. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it 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. Talk to your doctor if you are using marijuana (cannabis).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/glaucoma eye surgery), tell your doctor or dentist if you are taking or have ever taken this medication, and about all the other products you use (including prescription drugs, nonprescription drugs, and herbal products).Older adults may be more sensitive to the side effects of this drug, especially dizziness and fainting. These side effects can increase the risk of falling.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.

            DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.Some products that may interact with this drug include: other alpha blocker drugs (such as doxazosin, terazosin), beta blockers (such as atenolol, metoprolol, propranolol), drugs to treat erectile dysfunction-ED or pulmonary hypertension (such as sildenafil, tadalafil).Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine).Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.Some products have ingredients that could raise your heart rate or blood pressure. Tell your pharmacist what products you are using, and ask how to use them safely (especially cough-and-cold products, diet aids, or NSAIDs such as ibuprofen/naproxen).This medication may interfere with certain laboratory tests (including pheochromocytoma screening test), possibly causing false test results. Make sure laboratory personnel and all your doctors know you use this drug.

            OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: severe drowsiness, slow reactions.

            NOTES: Do not share this medication with others.Lifestyle changes such as stress reduction programs, exercise, and dietary changes may increase the effectiveness of this medicine. Talk to your doctor or pharmacist about lifestyle changes that might benefit you.Have your blood pressure and heart rate checked regularly while taking this medication. Learn how to monitor your own blood pressure, and share the results with your doctor.

            MISSED DOSE: If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

            STORAGE: Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.

            Information last revised February 2022. Copyright(c) 2022 First Databank, Inc.

            IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.

            Previous
            Next:

            Formulary

            FormularyPatient Discounts

            Adding plans allows you to compare formulary status to other drugs in the same class.

            To view formulary information first create a list of plans. Your list will be saved and can be edited at any time.

            Adding plans allows you to:

            • View the formulary and any restrictions for each plan.
            • Manage and view all your plans together – even plans in different states.
            • Compare formulary status to other drugs in the same class.
            • Access your plan list on any device – mobile or desktop.

            The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
            PA Prior Authorization
            Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
            QL Quantity Limits
            Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
            ST Step Therapy
            Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
            OR Other Restrictions
            Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
            Additional Offers
            Email to Patient

            From:

            To:

            The recipient will receive more details and instructions to access this offer.

            By clicking send, you acknowledge that you have permission to email the recipient with this information.

            Email Forms to Patient

            From:

            To:

            The recipient will receive more details and instructions to access this offer.

            By clicking send, you acknowledge that you have permission to email the recipient with this information.

            Previous
            Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.