Rapaflo and Flomax are both alpha-blockers commonly prescribed to treat benign prostatic hyperplasia.
Flomax (Tamsulosin) was one of the first drugs used for the treatment of BPH. It started selling in the 1990s and is the most widely used.
On the other hand, Rapaflo (Silodosin) was approved to treat BPH in 2008.
Keep reading for a full comparison of Rapaflo vs Flomax, including uses, differences, similarities, benefits, side effects, and more.
Rapaflo vs Flomax uses
Flomax and Rapaflo improve urinary symptoms in benign prostatic hyperplasia (BPH).
Doctors prescribe Flomax to relax the muscles around the prostate and improve urine flow. Rapaflo also relaxes the muscles around the prostate and urethra.
These drugs are also used off-label for:
- ureteral kidney stones
- urinary symptoms in women
- symptomatic relief in prostatitis
Notably, Rapaflo is better than Flomax at the off-label use of eliminating kidney stones.
Benefits of Rapaflo vs Flomax
Flomax is considered the most common treatment for BPH. It was one of the first treatments to provide symptomatic relief to these patients.
The benefits of Flomax are:
- A stronger, steady urine stream
- Improved urinary flow without straining
- Decreased dribbling and underwear staining
- Reduced urinary frequency, especially at night
- Decreased sensation of incomplete bladder emptying
The benefits of Rapaflo are similar to those of Flomax, and include:
- Relief of urinary symptoms in men
- Improved urinary stream
- Decreased urinary frequency
- Reduced sensation of incomplete bladder emptying
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Differences between Silodosin and Tamsulosin
The main difference between Rapaflo and Flomax is where they act. Rapaflo acts on alpha-1a receptors. This subtype of alpha receptors found mainly in urinary tissues is absent in vascular smooth muscle.
In contrast, Flomax acts on all alpha receptor subtypes, including those in urinary tissue and vascular tissue. Thus, one of the differences is that Rapaflo does not change blood pressure levels.
Also, since it is more specialized, Rapaflo is more likely to trigger additional responses. For instance, it can be used to eliminate urethral stones. It also reduces postvoid residual volume more effectively than Flomax.
One study found that Flomax is associated with reduced systolic blood pressure. It can lower blood pressure by up to 4 mmHg. In contrast, Rapaflo does not lower blood pressure.
How are Rapaflo and Flomax similar?
Both Rapaflo and Flomax belong to the same drug family. They are alpha-blockers and, as such, inhibit alpha-1 receptors in smooth muscle.
We can find these receptors in urinary and vascular tissue. Epinephrine and norepinephrine activate their action. These substances give smooth muscle tone maintaining a contractile state.
When these receptors are blocked, the muscle relaxes and increases urinary and blood flow. This is the mode of action shared by Flomax and Rapaflo.
Is Flomax better than Rapaflo?
Most studies show that Flomax and Rapaflo are similarly effective, with Rapaflo appearing slightly more effective than Flomax.
For example, in a study conducted at nine medical centers over 12 weeks, the researchers found significant improvement in urinary symptoms in 86% of patients taking Rapaflo and 82% of patients taking Flomax.
The difference is minimal if only net results in symptom scores are considered.
However, other studies show a greater effect of Rapaflo. For example, in patients with brachytherapy-induced urinary symptoms, urinary complaints decreased in both groups.
But the residual postvoid urine volume improved far more in patients taking Rapaflo. That is, the drug decreased the residual urine remaining after passing urine. Flomax also had a similar effect, but Rapaflo was better at it.
Although not significantly reflected in the symptoms, Rapaflo has a more profound impact on the urinary tract.
Side effects and risks of Rapaflo vs Flomax
Rapaflo and Flomax belong to the same group of alpha-blockers. Thus, they share the same adverse effects.
The most common are:
- Dizziness, weakness, or fatigue, usually due to hypotension
- Headache, sinusitis
- Back pain
- Nasal congestion
- Abnormal ejaculation, which may include difficulty ejaculating or a decrease in semen volume.
- Nausea, diarrhea, or abdominal pain
- Insomnia and other types of sleep disturbance
- Mild allergic reactions
In both cases, it is essential to seek immediate medical attention in case of severe adverse reactions.
For example, swelling of the face or tongue, prolonged and painful erections for hours, palpitations or chest pain, and fainting are considered severe adverse events.
The incidence of abnormal ejaculation is much higher in Rapaflo than in Flomax. Patients taking Rapaflo experienced ejaculation problems in 10%. This adverse effect is much more common than in Flomax, at 1%.
Therefore, those at higher risk of low blood pressure or taking antihypertensive drugs may benefit more from Rapaflo treatment.
But a patient with a medical history of abnormal ejaculation may have a better experience with Flomax.
Conclusion
We can summarize the information above in the following table:
| Feature | Flomax | Rapaflo |
| Mode of action | Inhibits all subtypes of alpha-1 receptors | Selectively inhibits alpha-1 receptors subtype A |
| BPH symptomatic improvements | Improvements in urinary symptoms | No significant difference in symptom improvements |
| Post-void residual volume | Reduced residual volume and sensation of incomplete bladder emptying | More profound reduction of post-void residual volume. No noticeable difference in symptoms compared to Flomax. |
| Effects on urinary stones | Mild improvements in calculi elimination | Off-label use. Significant improvement in calculi elimination |
| Adverse events | Increased incidence of hypotension compared to Rapaflo | Increased incidence of ejaculatory problems compared to Flomax |
Rapaflo and Flomax are two drugs used to relieve the urinary symptoms of BPH. Both are alpha-blockers and act on alpha-1 receptors.
The difference is that Flomax acts on all alpha-1 receptors while Rapaflo only blocks the A-subtype.
This receptor subtype is only found in urinary tissue. Therefore, Rapaflo is less likely to alter blood pressure compared to Flomax.
Improvements in residual volume after urination are more profound with Rapaflo compared to Flomax. However, the symptomatic improvement experienced by the patient is similar.
It is worth noting that some studies report a greater likelihood of ejaculation disturbances in Rapaflo. Therefore, the choice of the best BPH drug depends on the risk of adverse effects on the patient in question.
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