Cardura 4mg 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 1990
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, which lowers blood pressure, and by relaxing muscles in the prostate and bladder, which helps improve urine flow.
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
To maintain the quality and safety of your medication, store it at room temperature in a dry location, avoiding the bathroom. Keep all medications in a secure 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 specifically instructed to do so. Instead, consult with your pharmacist for guidance on the proper 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 is 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
To maintain the quality and safety of your medication, store it at room temperature in a dry location, avoiding the bathroom. Keep all medications in a secure 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 specifically instructed to do so. Instead, consult with your pharmacist for guidance on the proper 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 is 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 'first-dose phenomenon' (sudden drop in blood pressure).
- Be cautious when standing up quickly from a sitting or lying position to avoid dizziness or fainting (orthostatic hypotension).
- Avoid activities requiring mental alertness, such as driving or operating machinery, for at least 12 hours after the first dose or any dose increase.
- Avoid alcohol, as it can increase the risk of dizziness and low blood pressure.
- Stay hydrated, especially in hot weather or during exercise.
- Report any prolonged, painful erection (priapism) immediately to your doctor.
Available Forms & Alternatives
Available Strengths:
Generic Alternatives:
Dosing & Administration
Adult Dosing
Standard Dose:
Hypertension: Initial 1 mg once daily; Maintenance 1-8 mg once daily. BPH: Initial 1 mg once daily; Maintenance 1-8 mg once daily.
Dose Range:
1 - 16 mg
Condition-Specific Dosing:
Hypertension:
Initial 1 mg once daily, titrate up to 16 mg once daily if needed. Usual maintenance 1-8 mg.
Benign Prostatic Hyperplasia (BPH):
Initial 1 mg once daily, titrate up to 8 mg once daily if needed. Usual maintenance 1-8 mg.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established (Safety and efficacy not established for hypertension; limited data for BPH)
Adolescent:
Not established (Safety and efficacy not established for hypertension; limited data for BPH)
Dose Adjustments
Renal Impairment:
Mild:
No dosage adjustment necessary.
Moderate:
No dosage adjustment necessary.
Severe:
No dosage adjustment necessary.
Dialysis:
Doxazosin is highly protein bound and not dialyzable; no specific adjustment needed based on dialysis.
Hepatic Impairment:
Mild:
Use with caution.
Moderate:
Use with caution; consider lower initial dose and slower titration.
Severe:
Use with caution; not recommended due to lack of data and potential for increased exposure.
Pharmacology
Mechanism of Action
Doxazosin is a selective alpha-1 adrenergic antagonist. It competitively blocks postsynaptic alpha-1 adrenergic receptors, leading to vasodilation and a reduction in peripheral vascular resistance, thus lowering blood pressure. In BPH, it relaxes the smooth muscle in the prostate and bladder neck, reducing bladder outlet obstruction and improving urine flow.
Pharmacokinetics
Absorption:
Bioavailability:
62-69%
Tmax:
2-3 hours
FoodEffect:
Food does not significantly affect the extent of absorption.
Distribution:
Vd:
1.6 L/kg
ProteinBinding:
Approximately 98%
CnssPenetration:
Limited
Elimination:
HalfLife:
22 hours (range 19-24 hours)
Clearance:
Not available
ExcretionRoute:
Fecal (approximately 63%), Renal (approximately 9%)
Unchanged:
Less than 5% (renal)
Pharmacodynamics
OnsetOfAction:
1-2 hours
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 not having sex. If left untreated, this may lead to lasting sexual problems and impotence.
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 help:
Dizziness
Drowsiness
Fatigue
Weakness
* Headache
This is not an exhaustive list of possible 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 not having sex. If left untreated, this may lead to lasting sexual problems and impotence.
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 help:
Dizziness
Drowsiness
Fatigue
Weakness
* Headache
This is not an exhaustive list of possible 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 (syncope)
- Chest pain
- Shortness of breath
- Swelling in the ankles or feet
- Persistent or painful erection (priapism)
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
Your doctor will help you determine the best course of treatment and ensure that this medication is safe for you to use in conjunction with your other medications and health conditions.
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
Your doctor will help you determine the best course of treatment and ensure that this medication is safe for you to use in conjunction with your other medications and health conditions.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
When starting this medication, or after any dose increase, or if you restart it after stopping, avoid driving or engaging in activities that require alertness for 24 hours. Before operating a vehicle or performing tasks that demand attention, ensure you understand how this medication affects you.
To minimize the risk of dizziness or fainting, stand up slowly after sitting or lying down, and exercise caution when climbing stairs.
Monitor your blood pressure as directed by your healthcare provider. If you are scheduled for cataract surgery or any other eye procedure, consult with your doctor beforehand.
If you are taking this medication for an enlarged prostate, follow your doctor's instructions for regular rectal exams to check your prostate gland and undergo blood tests, including the PSA test.
If you have high blood pressure and are taking this medication, consult your doctor before using over-the-counter 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.
If you are 70 years or older, use this medication with caution, as you may be more susceptible to side effects.
Inform your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. Your doctor will discuss the benefits and risks of this medication with you, considering both your health and the baby's well-being.
When starting this medication, or after any dose increase, or if you restart it after stopping, avoid driving or engaging in activities that require alertness for 24 hours. Before operating a vehicle or performing tasks that demand attention, ensure you understand how this medication affects you.
To minimize the risk of dizziness or fainting, stand up slowly after sitting or lying down, and exercise caution when climbing stairs.
Monitor your blood pressure as directed by your healthcare provider. If you are scheduled for cataract surgery or any other eye procedure, consult with your doctor beforehand.
If you are taking this medication for an enlarged prostate, follow your doctor's instructions for regular rectal exams to check your prostate gland and undergo blood tests, including the PSA test.
If you have high blood pressure and are taking this medication, consult your doctor before using over-the-counter 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.
If you are 70 years or older, use this medication with caution, as you may be more susceptible to side effects.
Inform your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. Your doctor will discuss the benefits and risks of this medication with you, considering both your health and the baby's well-being.
Overdose Information
Overdose Symptoms:
- Profound hypotension (low blood pressure)
- Dizziness
- Fainting
- Tachycardia (rapid heart rate)
What to Do:
Seek immediate medical attention. Place the patient in a supine position with legs elevated. If necessary, treat with volume expanders and vasopressors. Dialysis is not effective. Call 911 or Poison Control at 1-800-222-1222.
Drug Interactions
Major Interactions
- PDE5 inhibitors (e.g., sildenafil, tadalafil, vardenafil): Concomitant use can lead to symptomatic hypotension. Start with lowest dose of PDE5 inhibitor and ensure patient is stable on alpha-blocker therapy before initiating.
- Other alpha-blockers (e.g., prazosin, terazosin): 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, potentially increasing hypotensive effects (though clinical significance is often minor due to doxazosin's wide therapeutic index).
- NSAIDs: May reduce the antihypertensive effect of doxazosin.
Minor Interactions
- Alcohol: May enhance hypotensive effects.
Monitoring
Baseline Monitoring
Blood Pressure (BP)
Rationale: To establish baseline and assess response to therapy.
Timing: Prior to initiation of therapy.
Orthostatic BP (lying and standing)
Rationale: To assess risk of orthostatic hypotension, especially with initial dose or dose titration.
Timing: Prior to initiation and after first dose/dose increase.
BPH Symptom Score (e.g., AUA Symptom Index)
Rationale: To quantify baseline BPH symptoms and monitor treatment efficacy.
Timing: Prior to initiation of therapy for BPH.
Routine Monitoring
Blood Pressure (BP)
Frequency: Regularly, especially during dose titration and periodically thereafter.
Target: Individualized, typically <130/80 mmHg for hypertension.
Action Threshold: If BP remains uncontrolled or if symptomatic hypotension occurs.
Orthostatic BP (lying and standing)
Frequency: Periodically, especially after dose increases or if patient reports dizziness/lightheadedness.
Target: No significant drop (e.g., <20 mmHg systolic, <10 mmHg diastolic) without symptoms.
Action Threshold: Symptomatic orthostatic hypotension or significant asymptomatic drop.
BPH Symptom Score
Frequency: Every 3-6 months or as clinically indicated.
Target: Reduction in symptom score.
Action Threshold: No improvement in symptoms after adequate titration or worsening symptoms.
Symptom Monitoring
- Dizziness
- Lightheadedness
- Syncope (fainting)
- Palpitations
- Fatigue
- Headache
- Edema (peripheral)
- Nasal congestion
- Priapism (rare, but serious)
Special Patient Groups
Pregnancy
Use during pregnancy only if the potential benefit justifies the potential risk to the fetus. Animal studies have shown adverse effects at high doses.
Trimester-Specific Risks:
First Trimester:
Limited human data; animal studies suggest potential for developmental toxicity at high doses.
Second Trimester:
Limited human data; animal studies suggest potential for developmental toxicity at high doses.
Third Trimester:
Limited human data; animal studies suggest potential for developmental toxicity at high doses. Alpha-blockers may affect fetal circulation or neonatal blood pressure.
Lactation
Doxazosin is excreted in human milk in small amounts. Use with caution during breastfeeding. Monitor breastfed infant for signs of hypotension (e.g., lethargy, poor feeding).
Infant Risk:
Low risk, but monitor for adverse effects.
Pediatric Use
Safety and effectiveness have not been established in pediatric patients. Not recommended for routine use in children for hypertension or BPH. Limited data exist for specific conditions like neurogenic bladder.
Geriatric Use
Elderly patients may be more sensitive to the hypotensive effects of doxazosin, particularly orthostatic hypotension. Initiate therapy with the lowest dose and titrate slowly. Monitor blood pressure closely.
Clinical Information
Clinical Pearls
- The 'first-dose phenomenon' (marked postural hypotension) is a known risk, especially with the initial dose or dose increases. Advise patients to take the first dose at bedtime and to avoid sudden changes in position.
- Doxazosin is effective for both hypertension and BPH, offering a dual benefit for men with both conditions.
- Extended-release (XL) formulations are available, which may reduce the incidence of orthostatic hypotension and allow for once-daily dosing without the bedtime recommendation.
- Patients should be screened for prostate cancer before initiating doxazosin for BPH, as BPH symptoms can mimic prostate cancer symptoms.
- Concomitant use with PDE5 inhibitors (e.g., sildenafil) requires careful consideration due to the risk of severe hypotension. Patients should be stable on alpha-blocker therapy before starting a PDE5 inhibitor, and the PDE5 inhibitor should be initiated at the lowest dose.
- Priapism (prolonged, painful erection) is a rare but serious side effect that requires immediate medical attention.
Alternative Therapies
- Other alpha-1 blockers (e.g., prazosin, terazosin, tamsulosin, alfuzosin, silodosin)
- For Hypertension: Thiazide diuretics, ACE inhibitors, ARBs, Beta-blockers, Calcium channel blockers
- For BPH: 5-alpha reductase inhibitors (e.g., finasteride, dutasteride), Anticholinergics (for overactive bladder symptoms), Beta-3 agonists, Surgical interventions (e.g., TURP)
Cost & Coverage
Average Cost:
$10 - $50 per 30 tablets (generic 4mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (for generic)
General Drug Facts
If your symptoms or health condition do not improve or worsen over time, it is essential to contact your doctor for further evaluation and guidance. To ensure your safety and the effectiveness of your treatment, never share your medication with others or take someone else's medication. It's also important to note that some medications may come with additional patient information leaflets, so be sure 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 for guidance. 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 detailed information about the overdose, including the name of the medication taken, the amount, and the time it occurred.