From the Guidelines
Using finasteride and tolterodine together is generally considered safe, as there are no significant known drug interactions between these medications. Finasteride (a 5-alpha-reductase inhibitor used for benign prostatic hyperplasia and male pattern baldness) and tolterodine (a muscarinic receptor antagonist used for overactive bladder) work through different mechanisms in the body. Finasteride reduces the conversion of testosterone to dihydrotestosterone by inhibiting the 5-alpha-reductase enzyme, while tolterodine blocks muscarinic receptors in the bladder to reduce urinary urgency and frequency.
When considering the use of these medications together, it's essential to weigh the benefits and risks. According to the AUA/SUFU guideline on the diagnosis and treatment of idiopathic overactive bladder 1, clinicians may consider pharmacologic interventions among patients with predominant OAB symptoms and who happen to have BPH, such as antimuscarinics, beta-3 agonists, alpha adrenergic antagonists, 5-alpha-reductase inhibitors, and phosphodiesterase-5 inhibitors.
Some key points to consider when taking these medications together include:
- The typical dosages for finasteride (5mg daily for BPH or 1mg for hair loss) and tolterodine (2mg twice daily or 4mg once daily for extended-release formulations) should be continued as prescribed.
- Each medication has its own side effect profile: finasteride may cause sexual side effects like decreased libido or erectile dysfunction, while tolterodine can cause dry mouth, constipation, or blurred vision.
- If you experience troublesome side effects or worsening of your condition, contact your healthcare provider for guidance rather than adjusting dosages yourself.
- The AUA guideline on management of benign prostatic hyperplasia 1 suggests that combination therapy with an alpha-adrenergic receptor blocker and a 5-alpha-reductase inhibitor is an effective treatment for patients with LUTS associated with demonstrable prostatic enlargement, but it does not specifically address the combination of finasteride and tolterodine. However, the more recent guideline 1 provides more relevant guidance on the use of antimuscarinics in patients with BPH and OAB.
Overall, the combination of finasteride and tolterodine can be considered safe and effective for patients with BPH and OAB, as long as the patient is closely monitored for potential side effects and interactions.
From the Research
Combination Therapy with Finasteride and Tolterodine
- The use of finasteride (a 5-alpha-reductase inhibitor) and tolterodine (a muscarinic receptor antagonist) together has not been directly studied in the provided evidence.
- However, studies have investigated the combination of alpha-blockers (which have a similar mechanism to finasteride in treating benign prostatic hyperplasia) and anticholinergics like tolterodine for the treatment of lower urinary tract symptoms (LUTS) and overactive bladder (OAB) symptoms.
Efficacy and Safety of Combination Therapy
- A study published in 2011 2 found that the combination of tolterodine tartrate and an alpha-receptor blocker improved symptoms of dysuria, urinary frequency, and urinary urgency in patients with benign prostatic hyperplasia and detrusor overactivity.
- Another study from 2011 3 showed that initial combined treatment with anticholinergics and alpha-blockers was effective and well-tolerated in men with LUTS related to BPH and OAB symptoms.
- A 2010 study 4 found that the addition of tolterodine extended-release to alpha-blocker therapy improved key OAB symptoms and was well-tolerated in men with persistent OAB symptoms, regardless of prostate size.
- A systematic review and network meta-analysis from 2024 5 compared the safety and efficacy of an alpha1-blocker plus mirabegron with an alpha1-blocker plus antimuscarinic in men with LUTS secondary to BPH and OAB, and found similar safety and efficacy profiles between the two combinations.
- A 2009 study 6 found that tolterodine treatment improved storage symptoms suggestive of OAB in men treated with alpha-blockers.
Considerations for Combination Therapy
- While the provided evidence does not directly address the combination of finasteride and tolterodine, it suggests that combination therapy with alpha-blockers and anticholinergics can be effective and well-tolerated in men with LUTS and OAB symptoms.
- However, it is essential to consider the potential risks and benefits of combination therapy and to monitor patients closely for any adverse effects, such as urinary retention or changes in urinary flow rate 2, 3, 4, 6.