What is the best non alpha (alpha) blocker for urinary bladder relaxation?

From the Guidelines

Mirabegron is the best non alpha blocker for urinary bladder relaxation, as it has been shown to improve frequency, urgency, and urge incontinence episodes compared to placebo or tolterodine, with a favorable safety profile, particularly in the elderly and in patients with multiple comorbidities. The use of mirabegron for bladder relaxation is supported by a meta-analysis of eight randomized controlled trials, which found that mirabegron monotherapy improves symptoms of overactive bladder compared to placebo or tolterodine 1. Some key points to consider when using mirabegron include:

• It is well tolerated in the elderly and in patients with multiple comorbidities
• It is contraindicated in patients with severe uncontrolled hypertension
• The most frequent adverse events are hypertension, UTIs, headache, and nasopharyngitis
• It does not affect voiding urodynamic parameters, and the overall change in PVR is small
• Long-term data on the efficacy and safety of mirabegron in men of any age with LUTS are not available Other options, such as anticholinergic medications like oxybutynin and tolterodine, may also be effective for bladder relaxation, but they may have more side effects and interactions compared to mirabegron. For example, oxybutynin and tolterodine can cause dry mouth, constaporation, and blurred vision, while mirabegron may cause increased blood pressure 1. It is essential to discuss the risks and benefits of each medication with your doctor to determine the best treatment option for your specific condition. In general, the choice of medication will depend on the individual patient's symptoms, medical history, and preferences. It is crucial to start with the lowest dose and increase if needed, and to monitor for any adverse events or interactions. Overall, mirabegron is a viable option for bladder relaxation, particularly for patients who cannot tolerate alpha blockers or have certain comorbidities.

From the FDA Drug Label

Mirabegron is an agonist of the human beta-3 adrenergic receptor (AR) as demonstrated by in vitro laboratory experiments using the cloned human beta-3 AR. Mirabegron relaxes the detrusor smooth muscle during the storage phase of the urinary bladder fill-void cycle by activation of beta-3 AR which increases bladder capacity Oxybutynin chloride exerts a direct antispasmodic effect on smooth muscle and inhibits the muscarinic action of acetylcholine on smooth muscle. Oxybutynin chloride relaxes bladder smooth muscle

The best non alpha blocker for urinary bladder relaxation is mirabegron, as it is a beta-3 adrenergic agonist that relaxes the detrusor smooth muscle during the storage phase of the urinary bladder fill-void cycle. Another option is oxybutynin, which exerts a direct antispasmodic effect on smooth muscle and inhibits the muscarinic action of acetylcholine on smooth muscle, relaxing bladder smooth muscle 2 3.

• Key points:
  • Mirabegron is a beta-3 adrenergic agonist
  • Oxybutynin exerts a direct antispasmodic effect on smooth muscle
  • Both drugs relax the bladder smooth muscle
  • Mirabegron is the best option as it is not an alpha blocker and has the desired effect on the bladder smooth muscle.

From the Research

Non Alpha Blockers for Urinary Bladder Relaxation

• Mirabegron is a β3 adrenoceptor agonist that has been shown to be effective in treating overactive bladder symptoms, including urinary urgency and urgency incontinence 4, 5, 6, 7, 8.
• The mechanism of action of mirabegron involves the relaxation of the detrusor muscle, which helps to reduce the frequency of urination and improve bladder control 4, 6.
• Clinical trials have demonstrated the efficacy and safety of mirabegron in treating overactive bladder symptoms, with significant improvements in micturition frequency, urgency incontinence, and health-related quality of life 4, 5, 7, 8.
• Mirabegron has been shown to be beneficial in patients who have previously discontinued antimuscarinic therapy due to lack of efficacy or poor tolerability 4, 5, 7.
• The most common adverse events associated with mirabegron are hypertension, dry mouth, constipation, and headache, although the incidence of dry mouth is lower compared to antimuscarinic agents 4, 5, 6, 7, 8.

Comparison with Antimuscarinics

• Mirabegron has been compared to antimuscarinic agents in clinical trials, with similar efficacy and improved tolerability 5, 7.
• Mirabegron may be a valuable treatment option for patients who experience troublesome side effects with antimuscarinic agents, such as dry mouth 5, 6, 8.
• The combination of mirabegron with α-adrenergic blockers does not appear to increase adverse effects, although dose reduction may be necessary in patients with severe renal failure or moderate hepatic failure 4.