From the Guidelines
Yes, Flomax (tamsulosin) can be given together with finasteride, as this combination therapy has been shown to be effective in managing moderate to severe benign prostatic hyperplasia (BPH) symptoms. These medications work in complementary ways, with Flomax relaxing the muscles in the prostate and bladder neck to provide quick relief of urinary symptoms, and finasteride shrinking the prostate gland over time by blocking the conversion of testosterone to dihydrotestosterone (DHT) 1. The typical dosage is Flomax 0.4 mg once daily and finasteride 5 mg once daily.
When used together, these medications can be more effective than either one alone for managing moderate to severe BPH symptoms, with Flomax working within days to weeks, and finasteride taking 3-6 months to show its full effect 1. Common side effects of Flomax include dizziness and orthostatic hypotension, while finasteride may cause sexual side effects such as decreased libido or erectile dysfunction. It's essential to take Flomax 30 minutes after the same meal each day and avoid suddenly standing up to minimize dizziness.
Some key points to consider when prescribing this combination therapy include:
- The safety of specific combinations other than finasteride plus doxazosin, terazosin, and alfuzosin has not been assessed 1.
- Combination therapy is associated with a higher rate of adverse events than monotherapy 1.
- The absolute risk reduction of combination therapy compared to tamsulosin monotherapy was 7.7% 1.
- Prostate size, as measured by ultrasound, is predictive of the natural history of BPH and the response to therapy with 5 alpha-reductase inhibitors like finasteride 1.
Overall, the combination of Flomax and finasteride can be a valuable treatment option for men with moderate to severe BPH symptoms, but it's crucial to weigh the benefits and risks and consider individual patient factors when making treatment decisions.
From the FDA Drug Label
Incubations with human liver microsomes showed no evidence of clinically significant metabolic interactions between tamsulosin hydrochloride and amitriptyline, albuterol (beta agonist), glyburide (glibenclamide) and finasteride (5alpha-reductase inhibitor for treatment of BPH)
The FDA drug label indicates that there is no clinically significant metabolic interaction between tamsulosin hydrochloride (Flomax) and finasteride. Therefore, Flomax can be given with finasteride 2.
From the Research
Interaction between Flomax and Finasteride
- There is no direct evidence of interactions between Flomax (tamsulosin) and finasteride in the provided studies.
- However, studies have compared the efficacy of alpha-blockers (such as tamsulosin) and 5-alpha reductase inhibitors (such as finasteride) in treating lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH) 3, 4.
- Finasteride has been shown to improve urinary symptoms in the long term, but is less effective than alpha-blockers such as doxazosin in the short term 3.
- Tamsulosin, on the other hand, has been shown to be effective in improving urinary flow and reducing symptoms, with minimal effects on blood pressure 5, 4.
Safety of Combination Therapy
- A study on the interaction between tadalafil (a phosphodiesterase 5 inhibitor) and alpha-blockers (including tamsulosin) found that tamsulosin had little hemodynamic interaction with tadalafil, suggesting that it may be safe to use tamsulosin with other medications 6.
- Another study compared the effects of terazosin and tamsulosin on ambulatory blood pressure and nocturnal orthostatic stress testing, and found that tamsulosin had a lower risk of symptomatic hypotensive events 7.