From the Guidelines
Silodosin is generally considered to have a lower risk of orthostatic hypotension compared to alfuzosin due to its high selectivity for alpha-1A adrenergic receptors. This is based on the most recent guideline evidence from the American Urological Association, which recommends considering the adverse event profiles of alpha blockers, including changes in blood pressure, when prescribing for patients with lower urinary tract symptoms attributed to benign prostatic hyperplasia (LUTS/BPH) 1.
Key Considerations
- Silodosin's high selectivity for alpha-1A adrenergic receptors means it primarily targets receptors in the prostate with minimal effect on blood vessels, reducing the risk of orthostatic hypotension.
- Alfuzosin, while also an alpha-1 blocker, has less subtype selectivity and therefore affects blood vessels more significantly, increasing the risk of orthostatic hypotension.
- The standard dose of silodosin is 8 mg once daily with a meal, and patients should be cautioned about possible dizziness when standing up quickly, especially elderly patients or those with a history of cardiovascular disease.
- Silodosin is more likely to cause ejaculatory dysfunction as a side effect, which may influence medication choice depending on patient priorities.
Clinical Implications
- When initiating either medication, patients should be monitored for signs of orthostatic hypotension, and silodosin may be the preferred option for patients with a history of cardiovascular disease or those taking antihypertensive medications due to its more favorable cardiovascular profile 1.
- The choice of alpha blocker should be based on patient age, comorbidities, and different adverse event profiles, including changes in blood pressure and ejaculatory dysfunction 1.
From the Research
Silodosin and Orthostatic Hypotension Risk
- Silodosin is a highly selective α1A-adrenoceptor antagonist that has been shown to have a low risk of orthostatic hypotension 2, 3, 4, 5, 6
- The incidence of orthostatic hypotension with silodosin has been reported to be less than 3% in clinical trials 2
- Silodosin's selectivity for the α1A-adrenergic receptor minimizes the propensity for blood pressure-related adverse effects mediated by α1B blockade, which may contribute to its low risk of orthostatic hypotension 2, 4
Comparison to Alfuzosin
- There is no direct comparison between silodosin and alfuzosin in the provided studies
- However, silodosin's pharmacological profile suggests that it may have a lower risk of orthostatic hypotension compared to other alpha-1 adrenergic receptor blockers, including alfuzosin 2, 3, 4, 5, 6
Adverse Effects
- The most commonly reported adverse effect of silodosin is abnormal or retrograde ejaculation, which occurs in approximately 20-28% of patients 2, 3, 4, 5, 6
- Other adverse effects, such as diarrhea, nasopharyngitis, and dizziness, are less common 6
- Orthostatic hypotension and syncope are rare adverse effects of silodosin, occurring in less than 3% of patients 2, 5, 6