What alpha agonist is used to treat Benign Prostatic Hyperplasia (BPH)?

From the Guidelines

Alpha-adrenergic antagonists (alpha blockers) are the primary medications used for benign prostatic hyperplasia (BPH), not alpha agonists. For BPH treatment, commonly prescribed alpha blockers include tamsulosin (Flomax) 0.4 mg daily, alfuzosin (Uroxatral) 10 mg daily, doxazosin (Cardura) starting at 1 mg daily and titrating up as needed, and terazosin (Hytrin) starting at 1 mg daily 1. These medications work by relaxing smooth muscle in the prostate and bladder neck, improving urine flow and reducing symptoms like frequency, urgency, and nocturia. They typically provide symptom relief within 1-2 weeks. Patients should be aware of potential side effects including dizziness, orthostatic hypotension, and retrograde ejaculation.

Some key points to consider when using alpha blockers for BPH treatment include:

• Starting with a low dose and titrating up as needed to minimize side effects
• Taking the first dose at bedtime to reduce the risk of orthostatic hypotension
• Avoiding sudden position changes, especially when starting therapy
• Monitoring for potential interactions with other medications, such as blood pressure medications

According to the most recent guidelines, combination therapy with an alpha blocker and a 5-alpha reductase inhibitor (5-ARI) should only be offered to patients with LUTS associated with demonstrable prostatic enlargement 1. This approach can help maximize symptom control and reduce the risk of clinical progression. However, the use of combination therapy should be individualized based on the patient's specific needs and medical history.

In terms of specific treatment options, the following alpha blockers are commonly used:

• Tamsulosin (Flomax) 0.4 mg daily
• Alfuzosin (Uroxatral) 10 mg daily
• Doxazosin (Cardura) starting at 1 mg daily and titrating up as needed
• Terazosin (Hytrin) starting at 1 mg daily

It's also important to note that alpha agonists are not recommended for the treatment of BPH, as they can actually worsen symptoms by increasing smooth muscle contraction in the prostate and bladder neck. Instead, alpha blockers are the preferred treatment option, as they can help relax smooth muscle and improve urine flow.

From the Research

Alpha Agonist for BPH

• The use of alpha agonists for the treatment of Benign Prostatic Hyperplasia (BPH) is not supported by the provided evidence, as the studies focus on alpha blockers, not agonists.
• Alpha blockers, such as tamsulosin, alfuzosin, doxazosin, and terazosin, have been shown to be effective in reducing symptoms of BPH and improving urinary flow 2, 3, 4, 5.
• Tamsulosin, in particular, has been found to be effective in patients with mild to severe Lower Urinary Tract Symptoms (LUTS) associated with BPH, with a rapid onset of action and minimal effects on blood pressure 2, 3.
• Combination therapy with alpha blockers and 5-alpha-reductase inhibitors (5ARIs) has also been shown to be effective in reducing BPH-related symptoms and preventing disease progression, particularly in patients with larger prostate volume and higher prostate-specific antigen (PSA) levels 6.

Mechanism of Action

• Alpha blockers work by relaxing the smooth muscle in the prostate and bladder neck, reducing bladder outflow resistance and improving urinary flow 2, 5.
• The subtype-selective alpha(1)-adrenoceptor antagonist tamsulosin has been found to have a high affinity for alpha(1A)- and alpha(1D)-adrenoceptors, which are predominantly found in the prostate gland and prostatic urethra 2, 3.

Efficacy and Tolerability

• Alpha blockers have been shown to be effective in reducing LUTS and improving urinary flow in patients with BPH, with response rates ranging from 20-65% 5.
• Tamsulosin and alfuzosin have been found to have a superior tolerability profile compared to other alpha blockers, with fewer hypotensive effects and less interference with concomitant antihypertensive therapy 2, 4.