What are the uses of Cardura (doxazosin)?

Uses of Cardura (Doxazosin)

Cardura (doxazosin) is primarily used for treating benign prostatic hyperplasia (BPH) and hypertension, with BPH being its most evidence-supported indication in current practice. 1, 2

Primary Uses

1. Benign Prostatic Hyperplasia (BPH)

• Doxazosin is an alpha-1 adrenergic receptor antagonist that relaxes smooth muscle in the prostate and bladder neck, improving urinary symptoms
• Effectively reduces both obstructive and irritative symptoms:
  • Weak or interrupted urinary stream
  • Feeling of incomplete bladder emptying
  • Delay in beginning urination
  • Frequent urination (day and night)
  • Urgency to urinate 1, 2
• Improves peak urinary flow rate within 1-2 weeks of starting treatment 2, 3
• Dosing: Typically started at lower doses (1mg) and titrated up to 4-8mg daily 1

2. Hypertension (Secondary Use)

• Doxazosin reduces blood pressure by decreasing peripheral vascular resistance
• Now considered a second-line or add-on agent for hypertension, not first-line therapy 1
• Important limitation: In the ALLHAT trial, doxazosin was associated with higher risk of heart failure compared to other antihypertensive agents 1, 4
• Typical dosing range: 1-16mg daily 1

Special Considerations

Dual Treatment Benefit

• Particularly valuable in men who have both BPH and hypertension 5
• Can effectively manage both conditions simultaneously, potentially reducing pill burden
• In the HABIT study, doxazosin improved BPH symptoms while also controlling blood pressure in patients with both conditions 5

Formulations

• Standard preparation requires titration through multiple steps
• Extended-release formulation (GITS - Gastrointestinal Therapeutic System) offers:
  • More convenient dosing
  • Fewer titration steps
  • Potentially fewer side effects 6

Side Effects and Precautions

• Most common adverse effects:
  • Orthostatic hypotension (particularly in older adults)
  • Dizziness
  • Fatigue (asthenia)
  • Nasal congestion 1
• First-dose phenomenon: Risk of significant hypotension with initial dose or dose increases
• Not recommended as monotherapy for hypertension due to increased risk of heart failure 1
• Should be avoided in patients with heart failure 1

Placement in Treatment Algorithm

For BPH:

1. First-line option along with other alpha-blockers (alfuzosin, tamsulosin, terazosin) 1
2. May be used in combination with 5-alpha reductase inhibitors (finasteride, dutasteride) for men with larger prostates 1
3. Consider as preferred option when patient also has hypertension requiring treatment

For Hypertension:

1. Not recommended as first-line therapy 1
2. Consider as second-line agent, particularly in men with concomitant BPH 1
3. May be added to other antihypertensive agents when additional BP control is needed

Clinical Pearls

• Effects on BPH symptoms should be noticeable within 1-2 weeks of starting treatment 2
• Take the first dose at bedtime to minimize orthostatic hypotension risk
• Doxazosin does not affect PSA levels, so it doesn't interfere with prostate cancer screening 2
• When treating both BPH and hypertension, monitor blood pressure closely as normotensive BPH patients will experience less BP reduction than hypertensive patients 5