Cardura XL 4mg Tablets
It is used to treat the signs of an enlarged prostate.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
Sep 1990
DEA Schedule
Not Controlled
Overview
What is this medicine?
Cardura XL is a medication used to treat high blood pressure (hypertension) and symptoms of an enlarged prostate (Benign Prostatic Hyperplasia or BPH). 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, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely. Take your medication with breakfast to help your body absorb it properly. Swallow the tablet whole - do not chew, break, or crush it. If you have difficulty swallowing, consult your doctor for guidance.
It's essential to continue taking your medication as directed by your doctor or healthcare provider, even if you start to feel better. This will help ensure that you receive the full benefits of the treatment.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication, store it at room temperature in a dry place, away from the bathroom. Keep all medications in a secure location, out of the reach of children and pets. When your medication is no longer needed or has expired, dispose of it properly. Do not flush it down the toilet or pour it down the drain unless instructed to do so by your pharmacist. If you're unsure about the best way to dispose of your medication, consult your pharmacist or check if there are any 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 treatment.
To get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely. Take your medication with breakfast to help your body absorb it properly. Swallow the tablet whole - do not chew, break, or crush it. If you have difficulty swallowing, consult your doctor for guidance.
It's essential to continue taking your medication as directed by your doctor or healthcare provider, even if you start to feel better. This will help ensure that you receive the full benefits of the treatment.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication, store it at room temperature in a dry place, away from the bathroom. Keep all medications in a secure location, out of the reach of children and pets. When your medication is no longer needed or has expired, dispose of it properly. Do not flush it down the toilet or pour it down the drain unless instructed to do so by your pharmacist. If you're unsure about the best way to dispose of your medication, consult your pharmacist or check if there are any 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 treatment.
Lifestyle & Tips
- Take the tablet whole; do not chew, crush, or divide it.
- Take at the same time each day, with or without food.
- Be aware of the 'first-dose phenomenon' (sudden drop in blood pressure, especially with the first dose or dose increase). Take the first dose at bedtime to minimize this risk.
- Avoid sudden changes in position (e.g., standing up quickly from sitting or lying down) to prevent dizziness or fainting.
- Avoid activities requiring mental alertness for the first few hours after the initial dose or dose increase.
- Limit alcohol intake, as it can increase the risk of dizziness and low blood pressure.
- Stay hydrated, especially in hot weather or during exercise, to help prevent low blood pressure.
- Inform your doctor or dentist that you are taking doxazosin before any surgery, especially cataract surgery, due to the risk of Intraoperative Floppy Iris Syndrome (IFIS).
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
For Hypertension: Initial 4 mg once daily. For BPH: Initial 4 mg once daily.
Dose Range:
4 - 8 mg
Condition-Specific Dosing:
Hypertension:
Initial 4 mg once daily. May be increased to 8 mg once daily after 7-14 days if needed to achieve desired blood pressure. Max 8 mg/day.
Benign Prostatic Hyperplasia (BPH):
Initial 4 mg once daily. May be increased to 8 mg once daily after 7-14 days if needed to achieve desired symptomatic relief and flow rate. 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:
Doxazosin is highly protein bound and not dialyzable; no specific adjustment needed beyond standard dosing.
Hepatic Impairment:
Mild:
Use with caution; monitor for increased effects.
Moderate:
Use with caution; consider lower starting dose and careful titration. Monitor closely for adverse effects.
Severe:
Not recommended due to extensive hepatic metabolism and lack of specific studies in severe impairment.
Pharmacology
Mechanism of Action
Doxazosin is a selective alpha-1 adrenergic receptor antagonist. It causes vasodilation by blocking alpha-1 receptors in peripheral arterioles, leading to a reduction in peripheral vascular resistance and blood pressure. In BPH, it relaxes the smooth muscle in the prostate and bladder neck, reducing urethral resistance and improving urine flow.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 62-69% (for immediate-release, extended-release may vary slightly but designed for sustained absorption)
Tmax:
8-9 hours (for extended-release formulation)
FoodEffect:
Absorption is not significantly affected by food for the extended-release formulation.
Distribution:
Vd:
Approximately 1.6 L/kg
ProteinBinding:
Approximately 98%
CnssPenetration:
Limited
Elimination:
HalfLife:
15-22 hours (for extended-release formulation)
Clearance:
Approximately 2.2 L/hr
ExcretionRoute:
Primarily fecal (63%), with a small amount (9%) excreted in urine.
Unchanged:
Less than 5% excreted unchanged in urine.
Pharmacodynamics
OnsetOfAction:
Gradual (due to extended-release formulation), typically within hours for blood pressure reduction.
PeakEffect:
Approximately 8-12 hours for blood pressure reduction.
DurationOfAction:
24 hours (due to extended-release formulation).
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Attention Immediately
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 medical help right away:
Signs of an allergic reaction, including:
+ 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, although not everyone will experience them. If you have any of the following side effects or any other concerns, 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, this medication can cause severe and potentially life-threatening side effects. If you experience any of the following symptoms, contact your doctor or seek medical help right away:
Signs of an allergic reaction, including:
+ 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, although not everyone will experience them. If you have any of the following side effects or any other concerns, 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, especially when standing up
- Fainting (syncope)
- Chest pain or palpitations
- Swelling in ankles or feet
- Persistent or painful erection (priapism, rare but requires immediate medical attention)
- Blurred vision or changes in vision
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 allergic reaction you experienced, including any symptoms that occurred.
If you have liver disease, as this may affect the safety and efficacy of the medication.
This list is not exhaustive, and it is crucial to discuss all your health conditions and medications with your doctor. Please provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
* Your complete medical history, including any health problems you are experiencing
Before starting, stopping, or changing the dose of any medication, including this one, you must consult with your doctor to ensure your safety. It is vital to verify that it is safe to take this medication in combination with all 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 allergic reaction you experienced, including any symptoms that occurred.
If you have liver disease, as this may affect the safety and efficacy of the medication.
This list is not exhaustive, and it is crucial to discuss all your health conditions and medications with your doctor. Please provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
* Your complete medical history, including any health problems you are experiencing
Before starting, stopping, or changing the dose of any medication, including this one, you must consult with your doctor to ensure your safety. It is vital to verify that it is safe to take this medication in combination with all your other medications and health conditions.
Precautions & Cautions
Important Information to Share with Your Healthcare Team
Inform all of your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
Precautions to Ensure Your Safety
Avoid driving and engaging in activities that require alertness until you understand how this medication affects you. You may notice a tablet-like substance in your stool, but this is a normal occurrence and not a cause for concern. If you have any questions or concerns, discuss them with your doctor.
To minimize the risk of dizziness or fainting, rise slowly from a sitting or lying position. Be cautious when climbing stairs. Monitor your blood pressure as directed by your healthcare provider.
Special Considerations
If you are scheduled to undergo cataract surgery or another eye procedure, inform your doctor. If you are taking this medication for an enlarged prostate, follow your doctor's instructions for regular rectal exams and blood tests, including the prostate-specific antigen (PSA) test.
If you have high blood pressure and are taking this medication, consult with 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.
Age-Related Precautions
If you are 70 years or older, use this medication with caution, as you may be more susceptible to side effects.
Gastrointestinal Considerations
If you have a history of narrowing or blockage in the gastrointestinal (GI) tract, discuss this with your doctor. Although rare, signs of GI tract blockage have occurred in individuals with this medical history. Seek immediate medical attention if you experience severe, persistent stomach pain, cramps, or bloating.
Contraindications and Pregnancy/Breastfeeding Considerations
This medication is not approved for use in females. If you are a female taking this medication, consult with your doctor if you are pregnant, plan to become pregnant, or are breastfeeding.
Inform all of your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
Precautions to Ensure Your Safety
Avoid driving and engaging in activities that require alertness until you understand how this medication affects you. You may notice a tablet-like substance in your stool, but this is a normal occurrence and not a cause for concern. If you have any questions or concerns, discuss them with your doctor.
To minimize the risk of dizziness or fainting, rise slowly from a sitting or lying position. Be cautious when climbing stairs. Monitor your blood pressure as directed by your healthcare provider.
Special Considerations
If you are scheduled to undergo cataract surgery or another eye procedure, inform your doctor. If you are taking this medication for an enlarged prostate, follow your doctor's instructions for regular rectal exams and blood tests, including the prostate-specific antigen (PSA) test.
If you have high blood pressure and are taking this medication, consult with 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.
Age-Related Precautions
If you are 70 years or older, use this medication with caution, as you may be more susceptible to side effects.
Gastrointestinal Considerations
If you have a history of narrowing or blockage in the gastrointestinal (GI) tract, discuss this with your doctor. Although rare, signs of GI tract blockage have occurred in individuals with this medical history. Seek immediate medical attention if you experience severe, persistent stomach pain, cramps, or bloating.
Contraindications and Pregnancy/Breastfeeding Considerations
This medication is not approved for use in females. If you are a female taking this medication, consult with your doctor if you are pregnant, plan to become pregnant, or are breastfeeding.
Overdose Information
Overdose Symptoms:
- Profound hypotension (low blood pressure)
- Dizziness
- Fainting
- Tachycardia (rapid heart rate)
What to Do:
Call 911 or your local emergency number immediately. Management is supportive, primarily involving placing the patient in a supine position with legs elevated to restore blood pressure. Vasopressors may be administered if necessary. Volume expanders may be considered. Doxazosin is highly protein bound and not dialyzable. Call 1-800-222-1222 for Poison Control.
Drug Interactions
Major Interactions
- PDE5 inhibitors (e.g., sildenafil, tadalafil, vardenafil): Significant additive hypotensive effects, especially within 4-6 hours of doxazosin dose. Concomitant use is not recommended or requires careful dose separation and monitoring.
- 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. May require dose adjustment of one or both agents.
- CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin, ritonavir): May increase doxazosin plasma concentrations, potentially increasing adverse effects. Monitor for increased hypotensive effects.
- CYP2D6 inhibitors (e.g., quinidine, fluoxetine): May increase doxazosin plasma concentrations, though less significant than CYP3A4.
Minor Interactions
- NSAIDs: May reduce the antihypertensive effect of doxazosin.
- Estrogens: May cause fluid retention, potentially antagonizing antihypertensive effects.
Monitoring
Baseline Monitoring
Blood Pressure (sitting and standing)
Rationale: To establish baseline and assess for orthostatic hypotension before initiating therapy.
Timing: Prior to initiation of therapy.
Symptoms of BPH (e.g., AUA symptom score)
Rationale: To establish baseline severity and monitor treatment efficacy.
Timing: Prior to initiation of therapy.
Routine Monitoring
Blood Pressure (sitting and standing)
Frequency: Regularly, especially during dose titration and periodically thereafter.
Target: Individualized, typically <130/80 mmHg for hypertension; monitor for orthostatic drop.
Action Threshold: Significant orthostatic drop (>20 mmHg systolic or >10 mmHg diastolic) or symptomatic hypotension.
Symptoms of BPH
Frequency: Periodically, especially after dose adjustments.
Target: Improvement in AUA symptom score.
Action Threshold: Lack of improvement or worsening symptoms.
Renal function (SCr, eGFR)
Frequency: Periodically, especially in patients with pre-existing renal impairment or on concomitant nephrotoxic drugs.
Target: Stable renal function.
Action Threshold: Significant decline in renal function.
Liver function tests (ALT, AST, bilirubin)
Frequency: Periodically, especially in patients with pre-existing hepatic impairment or symptoms of liver dysfunction.
Target: Within normal limits.
Action Threshold: Significant elevation of liver enzymes.
Symptom Monitoring
- Dizziness
- Lightheadedness
- Fainting (syncope)
- Palpitations
- Headache
- Fatigue
- Nasal congestion
- Peripheral edema
- Priapism (rare, but serious)
Special Patient Groups
Pregnancy
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 lacking.
Second Trimester:
Potential for fetal harm based on animal data; human data lacking.
Third Trimester:
Potential for fetal harm based on animal data; human data lacking.
Lactation
It is not known whether doxazosin is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from doxazosin, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Infant Risk:
Risk cannot be ruled out. Potential for hypotension and other adverse effects in the infant.
Pediatric Use
Safety and effectiveness in pediatric patients have not been established. Not recommended for use in children.
Geriatric Use
Geriatric patients may be more sensitive to the hypotensive effects of doxazosin, particularly orthostatic hypotension. Initiate therapy with caution and monitor blood pressure closely. No specific dose adjustment is typically required beyond careful titration.
Clinical Information
Clinical Pearls
- Cardura XL is an extended-release formulation, designed for once-daily dosing and should not be crushed, chewed, or divided.
- The 'ghost tablet' (empty shell) may be seen in the stool, which is normal and does not mean the medication was not absorbed.
- Warn patients about the 'first-dose phenomenon' and advise taking the initial dose at bedtime to mitigate orthostatic hypotension.
- Counsel patients on avoiding sudden positional changes to prevent dizziness and falls.
- Be cautious when co-administering with PDE5 inhibitors due to the significant risk of symptomatic hypotension.
- Doxazosin can cause Intraoperative Floppy Iris Syndrome (IFIS) during cataract surgery; patients should inform their ophthalmologist if they are taking or have taken doxazosin.
Alternative Therapies
- Other alpha-1 blockers for BPH/Hypertension: Tamsulosin (Flomax), Alfuzosin (Uroxatral), Silodosin (Rapaflo), Terazosin (Hytrin), Prazosin (Minipress)
- Other antihypertensives: Thiazide diuretics, ACE inhibitors, ARBs, Beta-blockers, Calcium channel blockers
- Other BPH treatments: 5-alpha reductase inhibitors (e.g., Finasteride, Dutasteride), anticholinergics (for overactive bladder symptoms), surgical options.
Cost & Coverage
Average Cost:
Varies, typically $30-$100+ per 30 tablets
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 2 (generic), Tier 3 (brand)
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. Some medications may come with an additional patient information leaflet, so it is a good idea to consult with your pharmacist for more information. If you have any questions or concerns about your medication, do not hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider for clarification and guidance. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When reporting the incident, be prepared to provide detailed information about the medication taken, including the dosage, time of ingestion, and any other relevant details.