Cardura XL 8mg 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
Jun 2000
DEA Schedule
Not Controlled
Overview
What is this medicine?
Doxazosin is a medication used to treat high blood pressure and symptoms of an enlarged prostate (BPH) in men. It works by relaxing blood vessels and the muscles around the prostate and bladder, which helps lower blood pressure and 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.
Continue taking your medication as directed by your doctor or healthcare provider, even if you start to feel better. It's essential to complete the full course of treatment as prescribed.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, away from the bathroom. Keep all medications in a safe location, out of the reach of children and pets. Dispose of unused or expired medications properly. Do not flush them down the toilet or pour them 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. You may also want to check if there are 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 dose, skip the missed dose and resume your regular 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.
Continue taking your medication as directed by your doctor or healthcare provider, even if you start to feel better. It's essential to complete the full course of treatment as prescribed.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, away from the bathroom. Keep all medications in a safe location, out of the reach of children and pets. Dispose of unused or expired medications properly. Do not flush them down the toilet or pour them 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. You may also want to check if there are 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 dose, skip the missed dose and resume your regular 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 with breakfast; do not crush, chew, or divide.
- Be aware of 'first-dose phenomenon' (though less common with ER): dizziness or fainting, especially when standing up quickly after the first dose or after a dose increase. Take the first dose at bedtime if possible, or when you can lie down for several hours.
- Avoid sudden changes in position (e.g., standing up quickly from sitting or lying down) to minimize dizziness or lightheadedness.
- Avoid activities requiring mental alertness, such as driving or operating machinery, until you know how this medication affects you.
- Limit or avoid alcohol consumption, as it can increase the risk of dizziness and low blood pressure.
- Inform your eye doctor that you are taking doxazosin if you are planning cataract surgery, as it can cause Intraoperative Floppy Iris Syndrome (IFIS).
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
4 mg once daily, titrated to 8 mg once daily
Dose Range:
4 - 8 mg
Condition-Specific Dosing:
benignProstaticHyperplasia:
Initial 4 mg once daily, maximum 8 mg once daily. Administer with breakfast.
hypertension:
Initial 4 mg once daily, maximum 8 mg once daily. Administer with breakfast.
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, but monitor response.
Hepatic Impairment:
Mild:
Use with caution; monitor closely for adverse effects.
Moderate:
Use with caution; consider starting at 4 mg and titrating slowly. Monitor closely for adverse effects.
Severe:
Not recommended due to extensive hepatic metabolism and lack of data.
Pharmacology
Mechanism of Action
Doxazosin is a selective alpha-1 adrenergic receptor antagonist. It blocks alpha-1 receptors in the smooth muscle of the prostate, bladder neck, and blood vessels. This blockade leads to relaxation of smooth muscle in the prostate and bladder neck, improving urine flow in BPH. In blood vessels, it causes vasodilation, leading to a reduction in peripheral vascular resistance and a decrease in blood pressure.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 62% (for IR, ER formulation designed for sustained release)
Tmax:
8-9 hours (for ER formulation)
FoodEffect:
Minimal effect on absorption or bioavailability of the extended-release formulation.
Distribution:
Vd:
Approximately 2.5 L/kg
ProteinBinding:
>98%
CnssPenetration:
Limited
Elimination:
HalfLife:
Approximately 22 hours (for ER formulation)
Clearance:
Not readily available for ER, but total body clearance is approximately 81 mL/min (for IR)
ExcretionRoute:
Primarily fecal (approximately 63%), renal (approximately 9%)
Unchanged:
<5% (in urine)
Pharmacodynamics
OnsetOfAction:
Gradual (due to extended-release formulation)
PeakEffect:
8-12 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 engaging in sexual activity. 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 persist, 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, 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. Your doctor can provide medical advice on managing side effects.
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 engaging in sexual activity. 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 persist, 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, 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. Your doctor can provide medical advice on managing side effects.
Seek Immediate Medical Attention If You Experience:
- Severe dizziness or lightheadedness
- Fainting (syncope)
- Chest pain
- Shortness of breath
- Persistent or bothersome swelling in the ankles or feet
- Priapism (prolonged erection lasting more than 4 hours - rare but serious)
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 your ability to take this medication.
This list is not exhaustive, and it is crucial to discuss all your medications, including prescription and over-the-counter drugs, natural products, and vitamins, with your doctor and pharmacist. They will help you determine if it is safe to take this medication in combination with your other medications and health conditions.
Remember, do not start, stop, or change the dose of any medication without first consulting your doctor to ensure your safety.
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 your ability to take this medication.
This list is not exhaustive, and it is crucial to discuss all your medications, including prescription and over-the-counter drugs, natural products, and vitamins, with your doctor and pharmacist. They will help you determine if it is safe to take this medication in combination with your other medications and health conditions.
Remember, do not start, stop, or change the dose of any medication without first consulting your doctor to ensure your safety.
Precautions & Cautions
Important Information to Share with Your Healthcare Team
Inform all 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 what appears to be a tablet in your stool; this is a normal occurrence and not a cause for concern. If you have any questions, consult 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 instructed by your healthcare provider.
Special Considerations
If you are scheduled to undergo cataract surgery or another eye procedure, discuss this with your doctor. If you are taking this medication for an enlarged prostate, follow your doctor's instructions for regular rectal exams and blood tests (PSA tests).
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.
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
This medication is not approved for use in females. If you are a female taking this medication and are pregnant, plan to become pregnant, or are breastfeeding, consult your doctor.
Inform all 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 what appears to be a tablet in your stool; this is a normal occurrence and not a cause for concern. If you have any questions, consult 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 instructed by your healthcare provider.
Special Considerations
If you are scheduled to undergo cataract surgery or another eye procedure, discuss this with your doctor. If you are taking this medication for an enlarged prostate, follow your doctor's instructions for regular rectal exams and blood tests (PSA tests).
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.
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
This medication is not approved for use in females. If you are a female taking this medication and are pregnant, plan to become pregnant, or are breastfeeding, consult your doctor.
Overdose Information
Overdose Symptoms:
- Profound hypotension (extremely 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 vasopressors and volume expanders. Doxazosin is highly protein bound and not dialyzable. Call 1-800-222-1222 (Poison Control).
Drug Interactions
Major Interactions
- PDE5 inhibitors (e.g., sildenafil, tadalafil, vardenafil): Risk of symptomatic hypotension.
- Other alpha-blockers (e.g., prazosin, terazosin): Additive hypotensive effects.
- Other antihypertensives (e.g., beta-blockers, diuretics, ACE inhibitors): Enhanced hypotensive effect.
Moderate Interactions
- CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin, ritonavir): May slightly increase doxazosin exposure, but generally not clinically significant for most patients.
- NSAIDs (e.g., ibuprofen, naproxen): May reduce the antihypertensive effect of doxazosin.
- Ergot alkaloids (e.g., ergotamine): Theoretical risk of increased peripheral vasoconstriction.
Minor Interactions
- Alcohol: May enhance hypotensive effects and dizziness.
Monitoring
Baseline Monitoring
Blood Pressure (sitting and standing)
Rationale: To establish baseline and assess for orthostatic hypotension risk.
Timing: Prior to initiation of therapy.
International Prostate Symptom Score (IPSS) / AUA Symptom Score
Rationale: To assess baseline BPH symptom severity.
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 symptomatic hypotension.
Action Threshold: Symptomatic orthostatic hypotension (dizziness, lightheadedness, syncope) or sustained systolic BP <90 mmHg.
BPH Symptom Assessment (IPSS/AUA score)
Frequency: Periodically (e.g., every 3-6 months) to assess treatment efficacy.
Target: Reduction in symptom score.
Action Threshold: Lack of symptomatic improvement after adequate titration.
Symptom Monitoring
- Dizziness
- Lightheadedness
- Syncope (fainting)
- Palpitations
- Fatigue
- Headache
- Nasal congestion
- Edema (peripheral)
Special Patient Groups
Pregnancy
Category C. Doxazosin should be used 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 adverse effects at high doses.
Second Trimester:
Limited human data; monitor maternal blood pressure closely.
Third Trimester:
Limited human data; monitor maternal blood pressure closely. Risk of neonatal hypotension is theoretical but not well-established.
Lactation
Doxazosin is excreted in human milk in small amounts. Use with caution in nursing mothers. The decision to discontinue nursing or discontinue the drug should take into account the importance of the drug to the mother.
Infant Risk:
L3 (Moderate risk, limited human data). Monitor breastfed infant for signs of hypotension (e.g., lethargy, poor feeding).
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. Start with the lowest dose (4 mg) and titrate slowly. Monitor blood pressure closely.
Clinical Information
Clinical Pearls
- Cardura XL is an extended-release formulation designed for once-daily dosing, which may improve patient adherence compared to immediate-release formulations.
- Administer Cardura XL with breakfast to ensure consistent absorption and minimize the risk of orthostatic hypotension during the day.
- While the 'first-dose phenomenon' (marked hypotension upon initial dosing) is less common with the extended-release formulation, patients should still be advised to be cautious, especially with the first dose or any dose increase.
- Patients should be warned about Intraoperative Floppy Iris Syndrome (IFIS) if they are undergoing cataract surgery, as alpha-blockers can cause this complication. They should inform their ophthalmologist about doxazosin use.
- Doxazosin XL tablets may be visible in the stool (ghost tablet) due to the non-absorbable outer shell of the extended-release system. This is normal and does not indicate that the medication was not absorbed.
- Effective for both BPH and hypertension, offering a dual benefit for men with both conditions.
Alternative Therapies
- Other alpha-1 adrenergic blockers (e.g., tamsulosin, alfuzosin, silodosin for BPH; prazosin, terazosin for hypertension)
- 5-alpha reductase inhibitors (e.g., finasteride, dutasteride for BPH)
- PDE5 inhibitors (e.g., tadalafil for BPH)
- Combination therapy (e.g., alpha-blocker + 5-alpha reductase inhibitor for BPH)
- Other classes of antihypertensives (e.g., ACE inhibitors, ARBs, beta-blockers, calcium channel blockers, diuretics for hypertension)
Cost & Coverage
Average Cost:
$30 - $100+ per 30 tablets (8mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (for generic), Tier 3 or higher (for brand)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. 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 is a good idea to consult with your pharmacist. If you have any questions or concerns about this medication, do not hesitate to discuss them with 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 detailed information about the overdose, including the substance taken, the amount, and the time it occurred.