Doxazosin 1mg Tablets
It is used to treat the signs of an enlarged prostate.It is used to treat high blood pressure.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Antihypertensive; Benign Prostatic Hyperplasia (BPH) Agent
Pharmacologic Class
Alpha-1 Adrenergic Blocker
Pregnancy Category
Category C
FDA Approved
Dec 1989
DEA Schedule
Not Controlled
Overview
What is this medicine?
Doxazosin is a medication used to treat high blood pressure (hypertension) and symptoms of an enlarged prostate (benign prostatic hyperplasia or BPH) in men. It works by relaxing blood vessels and muscles in the prostate and bladder, making it easier for blood to flow and for urine to pass.
How to Use This Medicine
Taking Your Medication Correctly
To get the most benefit from your medication, take it exactly as directed by your doctor. Carefully read all the information provided with your prescription, and follow the instructions closely. Continue taking your medication as prescribed by your doctor or healthcare provider, even if you start to feel better.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry location, avoiding the bathroom. Keep all medications in a safe place, 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, consult with your pharmacist for guidance on the best disposal method. You may also want to inquire about drug take-back programs in your area.
What to Do If You Miss 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. If you miss taking your medication for several days in a row, contact your doctor before restarting your medication regimen.
To get the most benefit from your medication, take it exactly as directed by your doctor. Carefully read all the information provided with your prescription, and follow the instructions closely. Continue taking your medication as prescribed by your doctor or healthcare provider, even if you start to feel better.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry location, avoiding the bathroom. Keep all medications in a safe place, 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, consult with your pharmacist for guidance on the best disposal method. You may also want to inquire about drug take-back programs in your area.
What to Do If You Miss 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. If you miss taking your medication for several days in a row, contact your doctor before restarting your medication regimen.
Lifestyle & Tips
- Take the first dose at bedtime to minimize the risk of dizziness or fainting (first-dose phenomenon).
- Avoid sudden changes in position (e.g., standing up quickly from a sitting or lying position) to prevent dizziness or fainting.
- Avoid activities requiring mental alertness (e.g., driving, operating machinery) for the first 12-24 hours after the first dose or dose increase.
- Limit alcohol consumption, as it can increase the risk of dizziness and low blood pressure.
- Maintain adequate hydration.
Available Forms & Alternatives
Available Strengths:
Dosing & Administration
Adult Dosing
Standard Dose:
Initial 1 mg orally once daily. Titrate slowly based on clinical response and tolerability.
Dose Range:
1 - 16 mg
Condition-Specific Dosing:
Hypertension:
Initial 1 mg once daily; may be increased to 2 mg, 4 mg, 8 mg, and 16 mg at 1- to 2-week intervals. Max: 16 mg/day.
Benign Prostatic Hyperplasia (BPH):
Initial 1 mg once daily; may be increased to 2 mg, 4 mg, and 8 mg at 1- to 2-week intervals. Max: 8 mg/day.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established
Adolescent:
Not established
Dose Adjustments
Renal Impairment:
Mild:
No dosage adjustment necessary.
Moderate:
No dosage adjustment necessary.
Severe:
No dosage adjustment necessary.
Dialysis:
Not significantly dialyzable; no specific adjustment needed, but monitor response.
Hepatic Impairment:
Mild:
Use with caution; monitor for increased effects.
Moderate:
Use with caution; consider lower initial dose and slower titration. Monitor closely.
Severe:
Not recommended due to lack of data and potential for increased exposure.
Pharmacology
Mechanism of Action
Doxazosin is a selective alpha-1 adrenergic receptor blocker. It causes vasodilation by blocking alpha-1 receptors on vascular smooth muscle, leading to a reduction in peripheral vascular resistance and blood pressure. In BPH, it relaxes smooth muscle in the prostate and bladder neck, reducing urethral resistance and improving urine flow.
Pharmacokinetics
Absorption:
Bioavailability:
62-69%
Tmax:
2-3 hours
FoodEffect:
Minimal effect on absorption.
Distribution:
Vd:
1.6 L/kg
ProteinBinding:
98%
CnssPenetration:
Limited
Elimination:
HalfLife:
22 hours
Clearance:
Not available
ExcretionRoute:
Feces (63%), Urine (9%)
Unchanged:
<5%
Pharmacodynamics
OnsetOfAction:
1-2 hours (for blood pressure lowering)
PeakEffect:
2-6 hours
DurationOfAction:
24 hours
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice 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
New or worsening chest pain
Shortness of breath
Swelling in the arms or legs
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. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other symptoms that bother you or do not go away, contact your doctor:
Dizziness
Drowsiness
Fatigue
Weakness
* Headache
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, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice 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
New or worsening chest pain
Shortness of breath
Swelling in the arms or legs
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. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other symptoms that bother you or do not go away, contact your doctor:
Dizziness
Drowsiness
Fatigue
Weakness
* Headache
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 lightheadedness
- Fainting or loss of consciousness
- Persistent headache
- Chest pain
- Shortness of breath
- Priapism (prolonged erection lasting more than 4 hours - seek immediate medical attention)
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.
If you have liver disease, as this may affect the use of this medication.
To ensure safe use, it is crucial to discuss the following with your doctor and pharmacist:
All medications you are currently taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins.
Any existing health problems, as this medication may interact with other drugs or health conditions.
Before making any changes to your medication regimen, consult with your doctor to confirm that it is safe to:
Start taking this medication
Stop taking this medication
* Change the dosage of this medication or any other medication you are taking
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.
If you have liver disease, as this may affect the use of this medication.
To ensure safe use, it is crucial to discuss the following with your doctor and pharmacist:
All medications you are currently taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins.
Any existing health problems, as this medication may interact with other drugs or health conditions.
Before making any changes to your medication regimen, consult with your doctor to confirm that it is safe to:
Start taking this medication
Stop taking this medication
* Change the dosage of this medication or any other medication you are taking
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 your first dose, as well as after any dose increase or when restarting the medication after a period of cessation. Before operating a vehicle or performing tasks that demand attention, make sure you understand how this medication affects you.
To minimize the risk of dizziness or fainting, stand up slowly when transitioning from a sitting or lying down position. Exercise caution when navigating stairs.
Follow your doctor's instructions for monitoring your blood pressure.
If you are scheduled to undergo cataract surgery or any other eye procedure, consult with your doctor beforehand.
For individuals taking this medication for an enlarged prostate, adhere to your doctor's recommendations regarding rectal exams to assess the prostate gland and blood tests, including the prostate-specific antigen (PSA) test.
If you have high blood pressure and are taking this medication, consult your doctor before using 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, and certain natural products or aids.
Individuals aged 70 years or older should exercise caution when using this medication, as they may be more susceptible to side effects.
If you are pregnant, planning to become pregnant, or are breastfeeding, inform your doctor to discuss the potential benefits and risks to both you and your baby.
To ensure your safety, avoid driving or engaging in activities that require alertness for 24 hours after your first dose, as well as after any dose increase or when restarting the medication after a period of cessation. Before operating a vehicle or performing tasks that demand attention, make sure you understand how this medication affects you.
To minimize the risk of dizziness or fainting, stand up slowly when transitioning from a sitting or lying down position. Exercise caution when navigating stairs.
Follow your doctor's instructions for monitoring your blood pressure.
If you are scheduled to undergo cataract surgery or any other eye procedure, consult with your doctor beforehand.
For individuals taking this medication for an enlarged prostate, adhere to your doctor's recommendations regarding rectal exams to assess the prostate gland and blood tests, including the prostate-specific antigen (PSA) test.
If you have high blood pressure and are taking this medication, consult your doctor before using 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, and certain natural products or aids.
Individuals aged 70 years or older should exercise caution when using this medication, as they may be more susceptible to side effects.
If you are pregnant, planning to become pregnant, or are breastfeeding, inform your doctor to discuss the potential benefits and risks to both you and your baby.
Overdose Information
Overdose Symptoms:
- Profound hypotension (low blood pressure)
- Dizziness
- Fainting
- Tachycardia (rapid heart rate)
What to Do:
Supportive care, place patient in supine position with legs elevated. If severe, administer vasopressors and volume expanders as needed. Dialysis is not effective. Call 1-800-222-1222 (Poison Control).
Drug Interactions
Major Interactions
- PDE5 inhibitors (e.g., sildenafil, tadalafil, vardenafil, avanafil): Concomitant use can lead to symptomatic hypotension. Start PDE5 inhibitor at lowest dose and only after patient is stable on alpha-blocker therapy.
- Other alpha-blockers: Increased risk of hypotension.
Moderate Interactions
- Antihypertensive agents (e.g., beta-blockers, diuretics, ACE inhibitors): Additive hypotensive effects.
- CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin, ritonavir): May increase doxazosin plasma concentrations, increasing risk of adverse effects.
- Antidepressants (e.g., tricyclic antidepressants): May enhance hypotensive effects.
Minor Interactions
- NSAIDs: May reduce the antihypertensive effect of doxazosin.
Monitoring
Baseline Monitoring
Blood Pressure (supine and standing)
Rationale: To establish baseline and assess for orthostatic hypotension risk.
Timing: Prior to initiation of therapy.
Benign Prostatic Hyperplasia (BPH) symptom score (e.g., AUA symptom index)
Rationale: To establish baseline symptom severity and monitor treatment efficacy.
Timing: Prior to initiation of therapy.
Routine Monitoring
Blood Pressure (supine and standing)
Frequency: Regularly, especially after dose changes and during titration.
Target: Individualized, typically <130/80 mmHg for hypertension; monitor for symptomatic hypotension.
Action Threshold: Symptomatic hypotension (dizziness, lightheadedness, syncope) or significant orthostatic drop (>20 mmHg systolic or >10 mmHg diastolic).
BPH symptom score
Frequency: Periodically (e.g., every 3-6 months or as clinically indicated).
Target: Reduction in symptom score.
Action Threshold: Lack of symptomatic improvement after adequate titration.
Symptom Monitoring
- Dizziness
- Lightheadedness
- Fainting/Syncope (especially with first dose or dose increases)
- Palpitations
- Fatigue
- Headache
- Nasal congestion
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 for fetal harm based on animal data; human data limited.
Second Trimester:
Potential for fetal harm based on animal data; human data limited.
Third Trimester:
Potential for fetal harm based on animal data; human data limited.
Lactation
Limited data suggest doxazosin is excreted into human milk. The amount is likely small, but the potential for adverse effects on the breastfed infant is unknown. Use with caution; monitor infant for drowsiness or hypotension.
Infant Risk:
Risk cannot be ruled out (L3).
Pediatric Use
Safety and effectiveness have not been established in pediatric patients. Not recommended for routine use.
Geriatric Use
Increased sensitivity to hypotensive effects and higher risk of orthostatic hypotension. Start with the lowest dose (1 mg) and titrate slowly. Monitor blood pressure closely, especially standing blood pressure.
Clinical Information
Clinical Pearls
- The 'first-dose phenomenon' (marked hypotension, dizziness, or syncope) can occur, especially with the initial dose or dose increases. To mitigate this, administer the first dose at bedtime.
- Advise patients to avoid situations where injury could result if syncope occurs (e.g., driving, operating machinery) for the first 12-24 hours after initiation or dose increase.
- Doxazosin is effective for both hypertension and BPH, offering a dual benefit for some patients.
- Sustained-release formulations (Cardura XL) may have a lower incidence of first-dose phenomenon due to slower absorption.
- Patients undergoing cataract surgery should inform their ophthalmologist about doxazosin use due to the risk of Intraoperative Floppy Iris Syndrome (IFIS).
Alternative Therapies
- Other alpha-1 blockers (e.g., prazosin, terazosin, tamsulosin, alfuzosin, silodosin)
- For hypertension: ACE inhibitors, ARBs, beta-blockers, calcium channel blockers, diuretics
- For BPH: 5-alpha reductase inhibitors (e.g., finasteride, dutasteride), anticholinergics (for overactive bladder symptoms), phosphodiesterase-5 inhibitors (e.g., tadalafil), surgical options.
Cost & Coverage
Average Cost:
Varies, typically $10-$50 per 30 tablets
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 2 (generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it is 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 it's a good idea to check with your pharmacist for more information. If you have any questions or concerns about your 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 emergency medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.