Minipress 1mg Capsules
It is used to treat high blood pressure.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Antihypertensive
Pharmacologic Class
Alpha-1 Adrenergic Blocker
Pregnancy Category
Category C
FDA Approved
Jun 1976
DEA Schedule
Not Controlled
Overview
What is this medicine?
Prazosin is a medication used to lower high blood pressure. It works by relaxing blood vessels, allowing blood to flow more easily. It can also be used for certain prostate conditions or to help with nightmares related to PTSD.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication as directed, with or without food, and continue taking it even if you start to feel better. It's essential to follow your doctor's or healthcare provider's advice on dosage and duration of treatment.
Storing and Disposing of Your Medication
Store your medication at room temperature, protected from light, and in a dry place. Avoid storing it in a bathroom. Keep all medications in a safe location, out of the reach of children and pets. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so. Instead, check with your pharmacist for guidance on the best disposal method. You may also want to explore local drug take-back programs.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for a missed one.
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication as directed, with or without food, and continue taking it even if you start to feel better. It's essential to follow your doctor's or healthcare provider's advice on dosage and duration of treatment.
Storing and Disposing of Your Medication
Store your medication at room temperature, protected from light, and in a dry place. Avoid storing it in a bathroom. Keep all medications in a safe location, out of the reach of children and pets. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so. Instead, check with your pharmacist for guidance on the best disposal method. You may also want to explore local drug take-back programs.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for a missed one.
Lifestyle & Tips
- Take the first dose, and any new increased dose, at bedtime to minimize the risk of dizziness or fainting (first-dose phenomenon).
- Rise slowly from a sitting or lying position to prevent dizziness or lightheadedness.
- Avoid sudden changes in body position.
- Avoid activities requiring mental alertness, such as driving or operating machinery, until you know how this medication affects you.
- Avoid alcohol, as it can increase the blood pressure-lowering effects and dizziness.
- Maintain a healthy diet and exercise routine as advised by your doctor.
- Do not stop taking this medication suddenly without consulting your doctor, as it can lead to a sudden increase in blood pressure.
Available Forms & Alternatives
Available Strengths:
Generic Alternatives:
Dosing & Administration
Adult Dosing
Standard Dose:
Initial: 1 mg orally 2 or 3 times daily. Maintenance: 6-15 mg/day in divided doses. Max: 20 mg/day.
Dose Range:
1 - 20 mg
Condition-Specific Dosing:
Hypertension:
Initial: 1 mg orally 2 or 3 times daily. Titrate slowly based on response and tolerance. Maintenance: 6-15 mg/day in divided doses. Max: 20 mg/day.
Benign Prostatic Hyperplasia (off-label):
Initial: 0.5 mg to 1 mg orally at bedtime. Titrate slowly to 2-5 mg once daily or in divided doses.
PTSD-related nightmares (off-label):
Initial: 1 mg orally at bedtime. Titrate slowly to 2-10 mg at bedtime, based on response.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established for routine use. For hypertension: Initial 0.05-0.1 mg/kg/day divided every 6-8 hours; Max 0.5 mg/kg/day or 20 mg/day, whichever is less.
Adolescent:
Not established for routine use. For hypertension: Initial 0.05-0.1 mg/kg/day divided every 6-8 hours; Max 0.5 mg/kg/day or 20 mg/day, whichever is less.
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment, use with caution.
Moderate:
No specific adjustment, use with caution, consider lower initial dose and slower titration.
Severe:
Use with caution, consider lower initial dose (e.g., 0.5 mg) and slower titration.
Dialysis:
Not significantly dialyzable. Administer after dialysis if dose adjustment is needed.
Hepatic Impairment:
Mild:
Use with caution, consider lower initial dose and slower titration.
Moderate:
Use with caution, consider lower initial dose and slower titration.
Severe:
Use with caution, consider lower initial dose and slower titration due to extensive hepatic metabolism.
Pharmacology
Mechanism of Action
Prazosin is a selective competitive antagonist of postsynaptic alpha-1 adrenergic receptors. This blockade leads to vasodilation of both arterioles and venules, resulting in a reduction in total peripheral resistance and venous return to the heart. This action lowers blood pressure without reflex tachycardia in most patients.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 50-70%
Tmax:
1-3 hours
FoodEffect:
Food may delay absorption but does not significantly affect the extent of absorption.
Distribution:
Vd:
Approximately 0.5 L/kg
ProteinBinding:
Approximately 95%
CnssPenetration:
Limited
Elimination:
HalfLife:
2-4 hours (average 2.5 hours)
Clearance:
Not available
ExcretionRoute:
Primarily via bile and feces (60-90%), with a small amount excreted in urine (6-10%).
Unchanged:
Less than 10%
Pharmacodynamics
OnsetOfAction:
Approximately 30 minutes
PeakEffect:
2-4 hours
DurationOfAction:
6-10 hours
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, this medication can cause severe and potentially life-threatening side effects. If you experience any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Severe dizziness or fainting
Fast or abnormal heartbeat
A painful erection (priapism) or an erection that lasts longer than 4 hours, which can occur even when you are not having sex. If left untreated, this condition may lead to permanent sexual dysfunction.
Other Possible Side Effects
Like all medications, this drug can cause side effects, although many people may not experience any or may only have mild symptoms. If you are bothered by any of the following side effects or if they persist, contact your doctor or seek medical attention:
Feeling dizzy, sleepy, tired, or weak
Headache
* Upset stomach
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, this medication can cause severe and potentially life-threatening side effects. If you experience any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Severe dizziness or fainting
Fast or abnormal heartbeat
A painful erection (priapism) or an erection that lasts longer than 4 hours, which can occur even when you are not having sex. If left untreated, this condition may lead to permanent sexual dysfunction.
Other Possible Side Effects
Like all medications, this drug can cause side effects, although many people may not experience any or may only have mild symptoms. If you are bothered by any of the following side effects or if they persist, contact your doctor or seek medical attention:
Feeling dizzy, sleepy, tired, or weak
Headache
* Upset stomach
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Severe dizziness or fainting (syncope), especially after the first dose or dose increase.
- Persistent lightheadedness.
- Rapid or pounding heartbeat.
- Swelling in the ankles or feet.
- Difficulty breathing.
- Chest pain.
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced as a result of the allergy.
All medications you are currently taking, including prescription and over-the-counter (OTC) medications, natural products, and vitamins. This information will help your doctor and pharmacist identify potential interactions between this medication and other substances you are taking.
* Any health problems you have, as this medication may interact with certain conditions.
To ensure your safety, it is crucial to verify that it is safe to take this medication with all your other medications and health conditions. Never start, stop, or change the dose of any medication without first consulting your doctor.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced as a result of the allergy.
All medications you are currently taking, including prescription and over-the-counter (OTC) medications, natural products, and vitamins. This information will help your doctor and pharmacist identify potential interactions between this medication and other substances you are taking.
* Any health problems you have, as this medication may interact with certain conditions.
To ensure your safety, it is crucial to verify that it is safe to take this medication with all your other medications and health conditions. Never start, stop, or change the dose of any medication without first consulting your doctor.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
To ensure your safety, avoid driving or engaging in activities that require alertness for 24 hours after taking your first dose, as well as after any dose increase or when restarting the medication after a period of discontinuation. Before resuming these activities, make sure you understand how this medication affects you.
To minimize the risk of dizziness or fainting, stand up slowly when getting up from a sitting or lying down position, and exercise caution when climbing stairs.
Follow your healthcare provider's instructions for monitoring your blood pressure.
Be aware that this medication may interfere with certain laboratory tests. Inform all your healthcare providers and laboratory personnel that you are taking this medication.
If you are scheduled to undergo cataract surgery or any other eye procedure, consult with your doctor beforehand.
Before using any over-the-counter (OTC) products that may increase blood pressure, such as cough or cold medications, diet pills, stimulants, non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen, or certain natural products or aids, discuss their use with your doctor.
Additionally, talk to your doctor before consuming alcohol. In hot weather or during physical activity, be cautious and drink plenty of fluids to avoid dehydration.
If you are pregnant, planning to become pregnant, or are breastfeeding, inform your doctor. You will need to discuss the potential benefits and risks of this medication to both you and your baby.
To ensure your safety, avoid driving or engaging in activities that require alertness for 24 hours after taking your first dose, as well as after any dose increase or when restarting the medication after a period of discontinuation. Before resuming these activities, make sure you understand how this medication affects you.
To minimize the risk of dizziness or fainting, stand up slowly when getting up from a sitting or lying down position, and exercise caution when climbing stairs.
Follow your healthcare provider's instructions for monitoring your blood pressure.
Be aware that this medication may interfere with certain laboratory tests. Inform all your healthcare providers and laboratory personnel that you are taking this medication.
If you are scheduled to undergo cataract surgery or any other eye procedure, consult with your doctor beforehand.
Before using any over-the-counter (OTC) products that may increase blood pressure, such as cough or cold medications, diet pills, stimulants, non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen, or certain natural products or aids, discuss their use with your doctor.
Additionally, talk to your doctor before consuming alcohol. In hot weather or during physical activity, be cautious and drink plenty of fluids to avoid dehydration.
If you are pregnant, planning to become pregnant, or are breastfeeding, inform your doctor. You will need to discuss the potential benefits and risks of this medication to both you and your baby.
Overdose Information
Overdose Symptoms:
- Profound hypotension (low blood pressure)
- Dizziness
- Drowsiness
- Loss of consciousness
- Shock
What to Do:
Call 911 or your local emergency number immediately. For less severe symptoms, contact a poison control center (1-800-222-1222). Management typically involves supporting blood pressure with intravenous fluids and vasopressors if needed. Keep the patient in a supine position with legs elevated.
Drug Interactions
Major Interactions
- PDE5 inhibitors (e.g., sildenafil, tadalafil): Significant additive hypotensive effects, risk of symptomatic hypotension.
- Other alpha-blockers (e.g., tamsulosin, doxazosin): Increased risk of hypotension.
Moderate Interactions
- Beta-blockers (e.g., propranolol, metoprolol): Additive hypotensive effects.
- Diuretics (e.g., hydrochlorothiazide, furosemide): Additive hypotensive effects.
- Calcium channel blockers (e.g., amlodipine, nifedipine): Additive hypotensive effects.
- Antihypertensive agents (general): Increased risk of hypotension.
- NSAIDs (e.g., ibuprofen, naproxen): May reduce the antihypertensive effect of prazosin.
Monitoring
Baseline Monitoring
Blood Pressure (BP) and Heart Rate (HR)
Rationale: To establish baseline cardiovascular status before initiating therapy and to assess the need for treatment.
Timing: Prior to first dose
Renal Function (BUN, Creatinine)
Rationale: To assess baseline kidney function, especially in patients with comorbidities, as elimination is partially renal.
Timing: Prior to first dose (if clinically indicated)
Hepatic Function (ALT, AST)
Rationale: To assess baseline liver function, as prazosin is extensively metabolized in the liver.
Timing: Prior to first dose (if clinically indicated)
Routine Monitoring
Blood Pressure (BP) - sitting and standing
Frequency: Regularly, especially during initial titration and dose changes (e.g., daily for first week, then weekly/monthly)
Target: Individualized, typically <130/80 mmHg for most hypertensive patients
Action Threshold: Symptomatic hypotension (dizziness, syncope), or BP outside target range requiring dose adjustment.
Heart Rate (HR)
Frequency: Regularly, especially during initial titration and dose changes
Target: 60-100 bpm (unless otherwise indicated)
Action Threshold: Persistent tachycardia or bradycardia outside normal limits, or symptomatic changes.
Symptom Monitoring
- Dizziness
- Lightheadedness
- Syncope (especially 'first-dose phenomenon')
- Palpitations
- Headache
- Nausea
- Fatigue
- Peripheral edema
Special Patient Groups
Pregnancy
Category C. Use only if the potential benefit justifies the potential risk to the fetus. Animal studies have shown adverse effects, but there are no adequate and well-controlled studies in pregnant women.
Trimester-Specific Risks:
First Trimester:
Potential risk, but human data are limited.
Second Trimester:
Potential risk, but human data are limited.
Third Trimester:
Potential risk, but human data are limited.
Lactation
Prazosin is excreted in small amounts into breast milk. The American Academy of Pediatrics considers it compatible with breastfeeding. Monitor the infant for signs of hypotension (e.g., lethargy, poor feeding).
Infant Risk:
Low risk (L3 - Moderately safe)
Pediatric Use
Safety and effectiveness have not been established in pediatric patients for hypertension. Use in children is generally off-label and requires careful consideration and monitoring by a specialist. Dosing is typically weight-based and titrated slowly.
Geriatric Use
Elderly patients may be more sensitive to the hypotensive effects of prazosin, particularly the 'first-dose phenomenon'. Start with a lower initial dose (e.g., 0.5 mg) and titrate more slowly. Monitor blood pressure closely, especially orthostatic changes.
Clinical Information
Clinical Pearls
- The 'first-dose phenomenon' (marked postural hypotension, syncope) is a significant concern; advise patients to take the first dose and any dose increases at bedtime.
- Prazosin is less commonly used as a first-line antihypertensive due to the availability of newer agents with better tolerability profiles, but it remains effective.
- It is often used off-label for PTSD-related nightmares due to its alpha-1 blocking effects on central adrenergic activity.
- Can be useful in patients with benign prostatic hyperplasia (BPH) and hypertension, though alpha-1a selective blockers are generally preferred for BPH alone.
- Patients should be advised to avoid activities requiring mental alertness for several hours after the initial dose or dose increase.
Alternative Therapies
- Other alpha-1 adrenergic blockers (e.g., Terazosin, Doxazosin, Alfuzosin, Tamsulosin, Silodosin)
- Other classes of antihypertensives (e.g., ACE inhibitors, ARBs, Calcium Channel Blockers, Thiazide Diuretics, Beta-blockers)
- For BPH: 5-alpha reductase inhibitors (e.g., Finasteride, Dutasteride)
- For PTSD nightmares: Clonidine (alpha-2 agonist), atypical antipsychotics (off-label)
Cost & Coverage
Average Cost:
$10 - $30 per 30 tablets (1mg generic)
Generic Available:
Yes
Insurance Coverage:
Tier 1 (Generic) or Tier 2 (Preferred Brand)
General Drug Facts
If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist for more details. If you have any questions or concerns about this medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When reporting the incident, be prepared to provide information about the medication taken, the amount, and the time it occurred.