A fixed-dose combination (FDC) therapy for the management of moderate to severe symptoms of Benign Prostatic Hyperplasia (BPH). Silodosin is a highly selective alpha-1A adrenergic receptor antagonist that provides rapid relief from dynamic symptoms (e.g., urinary flow). Dutasteride is a dual 5-alpha reductase inhibitor (inhibits both Type I and Type II isoenzymes) that reduces prostate volume by inhibiting the conversion of testosterone to dihydrotestosterone (DHT), addressing the static component of BPH. This combination provides synergistic relief of lower urinary tract symptoms (LUTS) and reduces the risk of disease progression and acute urinary retention.
Adult: One tablet (Silodosin 8mg + Dutasteride 0.5mg) orally once daily, preferably with the same meal each day to standardize absorption.
Note: Swallow the tablet whole with a glass of water, preferably with or immediately after a meal (to reduce risk of orthostatic hypotension and standardize Silodosin absorption). Do not crush, break, or chew the tablet. If a dose is missed, take it as soon as remembered unless it is almost time for the next dose. Do not double the dose.
The combination works via two complementary mechanisms. Silodosin selectively blocks alpha-1A adrenoceptors, which are predominant in the prostate stroma, bladder neck, and prostatic urethra. This blockade inhibits the sympathetically mediated contraction of smooth muscle in these areas, reducing dynamic urethral resistance and improving urine flow. Dutasteride inhibits both Type I and Type II isoforms of the enzyme 5-alpha reductase, which is responsible for converting testosterone to the more potent androgen dihydrotestosterone (DHT) within the prostate gland. Reduced intraprostatic DHT leads to involution of the epithelial glandular tissue, decreasing prostate volume (static component) over time.
Pregnancy: Pregnancy Category X (Dutasteride). This combination is FOR USE IN MEN ONLY. Dutasteride is absorbed through the skin and can cause fetal harm if a pregnant woman is exposed. Women who are or may become pregnant must not handle crushed or broken tablets.
Driving: May cause dizziness, vertigo, or somnolence, especially during the first few weeks of therapy. Patients should be cautioned about engaging in hazardous activities, such as driving or operating machinery, until they are certain the medication does not affect them adversely.
| Strong CYP3A4 Inhibitors (Ketoconazole, Itraconazole, Ritonavir, Clarithromycin) | Significantly increases Silodosin plasma concentration, increasing risk of adverse effects like hypotension. Contraindicated in hepatic impairment. | Major |
| Other Alpha-Adrenergic Blockers (Prazosin, Tamsulosin, Terazosin, Doxazosin) | Additive hypotensive and orthostatic effects. Generally not recommended. | Major |
| Antihypertensives (Beta-blockers, ACE inhibitors, Calcium channel blockers, Diuretics) | Potentiates hypotensive effect. Monitor blood pressure, especially during initiation. | Moderate |
| Phosphodiesterase-5 Inhibitors (Sildenafil, Tadalafil, Vardenafil) | Additive vasodilatory and hypotensive effects. Use with caution and separate administration times. | Moderate |
| Moderate CYP3A4 Inhibitors (Erythromycin, Verapamil, Diltiazem) | May increase Silodosin levels. Use with caution and monitor. | Moderate |
| Warfarin | Dutasteride is highly protein-bound; theoretical displacement interaction. Monitor INR closely, especially during initiation/discontinuation. | Moderate |