1. Clinical Overview
A fixed-dose combination (FDC) medication used for the treatment of symptomatic Benign Prostatic Hyperplasia (BPH). Tamsulosin is a selective alpha-1A adrenergic receptor antagonist that relaxes smooth muscle in the prostate and bladder neck, improving urine flow. Finasteride is a 5-alpha-reductase inhibitor that reduces prostate volume by blocking the conversion of testosterone to dihydrotestosterone (DHT). This combination provides rapid symptomatic relief (from tamsulosin) and long-term disease modification by reducing prostate size and risk of complications (from finasteride).
| Onset | Duration | Bioavailability |
|---|---|---|
| Tamsulosin: Symptomatic relief may begin within 1-2 weeks, with peak effect in 4-6 weeks. Finasteride: Reduction in prostate size begins within 3-6 months, with maximum effect at 6-12 months. | Tamsulosin: Approximately 24 hours (once-daily dosing). Finasteride: Long-term, requires continuous administration; DHT levels return to baseline within 14 days of discontinuation. | Tamsulosin: ~100% (when taken after a meal). Finasteride: ~63-80% (not significantly affected by food). |
2. Mechanism of Action
The combination works via two complementary pathways. Tamsulosin selectively blocks alpha-1A adrenoceptors located in the smooth muscle of the prostate, prostatic capsule, and bladder neck. This inhibition prevents norepinephrine-induced contraction, leading to muscle relaxation, reduced dynamic obstruction, and improved urinary flow. Finasteride is a competitive and specific inhibitor of Type II 5-alpha-reductase, the intracellular enzyme that converts testosterone to the more potent androgen dihydrotestosterone (DHT). DHT is the primary androgen responsible for prostate growth. By reducing intraprostatic DHT levels by up to 70-90%, finasteride induces epithelial apoptosis, leading to a significant reduction in prostate volume over time, thus addressing the static component of obstruction.
3. Indications & Uses
- Symptomatic treatment of moderate to severe Benign Prostatic Hyperplasia (BPH) in patients with an enlarged prostate (>30-40g)
- Reduction in the risk of acute urinary retention (AUR) and the need for BPH-related surgery
4. Dosage & Administration
Adult Dosage: One tablet (Tamsulosin 0.4mg + Finasteride 5mg) orally once daily, preferably 30 minutes after the same meal each day.
Administration: Swallow the tablet whole with a glass of water. Do not crush, chew, or break the tablet. Should be taken after a meal (preferably breakfast or dinner) to ensure consistent absorption and reduce the risk of dizziness/orthostasis. The capsule/tablet should be handled with care; pregnant women should avoid contact with crushed or broken tablets due to finasteride absorption risk.
5. Side Effects
Common side effects may include:
- Decreased libido
- Ejaculation disorders (retrograde/ reduced ejaculate volume)
- Erectile dysfunction
- Dizziness
- Postural hypotension
- Headache
- Asthenia (weakness)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Other Alpha-blockers (e.g., Prazosin, Doxazosin) | Additive hypotensive effects, increased risk of orthostasis and syncope. | Major |
| Phosphodiesterase-5 Inhibitors (e.g., Sildenafil, Tadalafil) | Additive vasodilatory and hypotensive effects. | Major |
| Strong CYP3A4 Inhibitors (e.g., Ketoconazole, Itraconazole, Ritonavir, Clarithromycin) | May significantly increase tamsulosin plasma concentrations, increasing risk of adverse effects like hypotension. Contraindicated or requires close monitoring. | Major |
| Antihypertensives (Beta-blockers, ACE Inhibitors, Calcium channel blockers, Diuretics) | Potential additive blood pressure lowering effect. | Moderate |
| Warfarin | Finasteride has been reported to potentially enhance the anticoagulant effect; monitor INR closely. | Moderate |
| Herbal supplements (e.g., Saw Palmetto) | Theoretical additive effect; clinical significance unknown. | Minor |
7. Patient Counselling
- DO take the tablet once daily, 30 minutes after the same meal (e.g., breakfast) every day.
- DO swallow the tablet whole with water. Do not crush or chew.
- DO inform all your doctors (especially surgeons and ophthalmologists) that you are taking this medicine.
- DO get regular follow-ups with your urologist for prostate examination and PSA monitoring.
- DONT donate blood while on this medication and for at least 1 month after stopping (to prevent fetal exposure through transfusion to a pregnant woman).
- DONT stop taking the medication without consulting your doctor, even if you feel better.
- DONT handle crushed or broken tablets if you are a woman who is or may become pregnant.
8. Toxicology & Storage
Overdose: Primarily related to the alpha-blocking effects of tamsulosin: Severe hypotension, dizziness, tachycardia, syncope. Symptoms of finasteride overdose are not well characterized but may include heightened pharmacological effects.
Storage: Store at room temperature (15-30°C). Protect from light and moisture. Keep in the original blister pack or container. Keep out of reach of children. Do not use after the expiry date printed on the pack.