What is the maximum recommended dose of Cardura (doxazosin)?

Maximum Recommended Dose of Cardura (Doxazosin)

The maximum recommended dose of Cardura (doxazosin) is 16 mg once daily for hypertension and 8 mg once daily for benign prostatic hyperplasia (BPH). 1

Dosing Guidelines by Indication

For Hypertension:

• Initial dose: 1 mg once daily
• Titration: Dose may be doubled up to 16 mg once daily as needed to achieve desired blood pressure reduction
• Maximum dose: 16 mg once daily 1

For Benign Prostatic Hyperplasia (BPH):

• Initial dose: 1 mg once daily (morning or evening)
• Titration: May be titrated at 1-2 week intervals to 2 mg, then 4 mg, then 8 mg
• Maximum dose: 8 mg once daily 1, 2

Administration Considerations

1. Monitoring: Following the initial dose and with each dose increase, blood pressure should be monitored for at least 6 hours 1

2. Restarting therapy: If doxazosin is discontinued for several days, therapy should be restarted using the initial dosing regimen 1

3. Timing: Can be administered in the morning or evening 1

4. Formulations:

   • Standard formulation (Cardura): Requires careful titration starting at 1 mg
   • Extended-release formulation (Cardura XL/GITS): Allows higher initial dosage (4 mg) with fewer titration steps 3, 4

Safety Considerations

Common Side Effects:

• Orthostatic hypotension (especially in older adults)
• Dizziness, headache, and fatigue 5
• First-dose hypotension 2

Precautions:

• Alpha blockers are associated with orthostatic hypotension, particularly in older adults 2
• They may be considered as second-line agents in patients with concomitant BPH 2
• Alpha blockers are not recommended as first-line agents for hypertension unless the patient has BPH 6

Clinical Pearls

1. The pharmacokinetic profile of the extended-release formulation (Cardura XL/GITS) allows for a higher initial dose (4 mg) and fewer titration steps compared to the standard formulation 3, 4

2. Nearly half of patients with BPH may achieve symptom relief at the 4 mg dose of doxazosin GITS 4

3. While doxazosin can cause clinically significant blood pressure decreases in hypertensive patients (approximately 8/11 mm Hg), the blood pressure effects in normotensive patients are generally not clinically significant (approximately 4/2 mm Hg) 5

4. For patients with BPH, significant improvements in urinary flow rates and symptom scores can be observed as early as 2-4 weeks after starting treatment 7

5. When used for hypertension management, doxazosin is generally not considered a first-line agent, as other classes (ACE inhibitors, ARBs, calcium channel blockers, or thiazide diuretics) have better outcomes for cardiovascular morbidity and mortality 6

Remember that while the maximum dose is clearly defined in the FDA labeling, the optimal dose should be the lowest effective dose that controls symptoms while minimizing side effects.