Can Flomax (tamsulosin) and Alfuzosin be taken 12 hours apart?

Alpha Blockers for BPH: Tamsulosin and Alfuzosin Dosing

Tamsulosin and alfuzosin should not be taken together, even 12 hours apart, as this would constitute duplicate therapy with two alpha-1 blockers, increasing the risk of adverse effects without additional therapeutic benefit.

Pharmacological Considerations

Alpha-1 blockers like tamsulosin (Flomax) and alfuzosin are both effective treatments for lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH). However, they work through similar mechanisms:

• Mechanism of action: Both medications are alpha-1 adrenergic receptor antagonists that relax smooth muscle in the prostate and bladder neck, improving urinary flow 1
• Selectivity: Tamsulosin is more selective for alpha-1A and alpha-1D receptors, while alfuzosin is less subtype-selective 2
• Efficacy: Both medications provide similar improvements in symptom scores (4-7 points on the IPSS) 1

Risks of Concurrent Use

Taking both medications, even 12 hours apart, presents several concerns:

1. Duplicate therapy: Both medications target the same receptors and produce similar effects
2. Increased adverse effects risk:
   • Orthostatic hypotension
   • Dizziness
   • Headache
   • Asthenia (weakness)
   • Sexual dysfunction

Comparative Efficacy and Safety

When choosing between these medications:

• Efficacy: Studies show comparable improvements in urinary symptoms between tamsulosin and alfuzosin 3
• Cardiovascular effects: Tamsulosin OCAS (oral controlled absorption system) has shown fewer vascular effects than alfuzosin XL in direct comparison studies 4
• Dosing convenience: Tamsulosin is typically dosed once daily (0.4mg), while alfuzosin is available in both once-daily (XL) and three-times daily formulations 3
• Blood pressure effects: In comparative studies, tamsulosin had no statistically significant effect on blood pressure compared to baseline, while alfuzosin induced significant reductions in both standing and supine blood pressure 3

Appropriate Management Options

Instead of combining these medications, consider:

1. Optimize current therapy:

   • Ensure adequate dosing of the current alpha blocker
   • Allow sufficient time for full effect (may take 2-4 weeks)
   • Assess adherence to therapy

2. Switch to the alternative agent:

   • If one agent is ineffective or poorly tolerated, discontinue it completely before starting the other
   • Allow 24-48 hours between stopping one and starting the other to minimize adverse effects

3. Consider combination therapy with different drug classes:

   • Alpha blocker + 5-alpha reductase inhibitor (finasteride, dutasteride) for enlarged prostates
   • Alpha blocker + anticholinergic for mixed symptoms with overactive bladder

Important Precautions

• Intraoperative Floppy Iris Syndrome: Both medications can cause IFIS during cataract surgery; inform ophthalmologists before surgery 1
• First-dose effect: Start with recommended dose; tamsulosin typically doesn't require dose titration 5
• Drug interactions: Both medications may interact with antihypertensives, phosphodiesterase-5 inhibitors, and other medications that affect blood pressure 6

In conclusion, combining tamsulosin and alfuzosin, even with separated dosing times, provides no additional benefit while increasing the risk of adverse effects. The appropriate approach is to optimize therapy with one agent or switch completely to the alternative if necessary.