Prostanil MR

• Benign Prostatic Hyperplasia (BPH):
  Treatment of symptoms associated with BPH, including urinary hesitancy, weak stream, and incomplete bladder emptying.
• Adjunctive Use for Ureteral Stones (off-label):
  To facilitate the passage of distal ureteral calculi.
• Neurogenic Bladder Dysfunction (off-label):
  Used to improve bladder emptying in select cases.

• Adults:
  0.4 mg orally once daily, approximately 30 minutes after the same meal each day. If tolerated and response inadequate after 2–4 weeks, dose may be increased to 0.8 mg once daily.
• Pediatrics:
  Not recommended.
• Elderly:
  No dosage adjustment; monitor blood pressure.
• Renal Impairment:
  Use with caution in severe impairment; no routine adjustment required in mild to moderate cases.
• Hepatic Impairment:
  Use cautiously in severe impairment.
• Administration:
  Swallow capsules whole; do not crush or chew.

Tamsulosin is a selective antagonist of the alpha-1A adrenergic receptors located predominantly in the smooth muscle of the prostate, bladder neck, and urethra. By blocking these receptors, tamsulosin induces relaxation of smooth muscle, thereby reducing urethral resistance and improving urine flow in patients with BPH. Its selectivity minimizes systemic vasodilatory effects on vascular alpha-1B receptors.

• Absorption: Rapid and nearly complete; peak plasma concentration in 4–5 hours.
• Bioavailability: Approximately 30–40%.
• Distribution: Highly protein-bound (94–99%).
• Metabolism: Extensively metabolized by hepatic CYP3A4 and CYP2D6 enzymes.
• Half-life: Approximately 9–15 hours.
• Elimination: Mainly fecal (~60%) and urinary (~9%) excretion of metabolites.

• Pregnancy: Not applicable; no indication in women.
• Lactation: Safety unknown; not recommended.

• Alpha-1 Adrenergic Receptor Blocker
• Selective Alpha-1A Antagonist

• Known hypersensitivity to tamsulosin or excipients.
• Severe hepatic impairment (relative contraindication).
• Use in women and children (no approved indication).

• Risk of orthostatic hypotension, especially with first dose.
• Intraoperative Floppy Iris Syndrome reported during cataract surgery.
• Use with caution in severe renal or hepatic impairment.
• Monitor for priapism, though rare.

• Common: Dizziness, headache, rhinitis, abnormal ejaculation.
• Serious: Hypotension, syncope, allergic reactions, intraoperative floppy iris syndrome.

• CYP3A4 inhibitors (ketoconazole, itraconazole) increase tamsulosin levels.
• Additive hypotensive effects with antihypertensives and PDE-5 inhibitors.
• Alcohol may enhance hypotensive effects.

• FDA highlights intraoperative floppy iris syndrome risk in cataract surgery patients.
• Guidelines recommend tamsulosin as first-line treatment for BPH symptoms.

• Store at 20°C to 25°C (68°F to 77°F).
• Protect from moisture and light.
• Do not freeze.
• Keep capsules in original container, do not crush or chew.