Naftopidil

• Benign Prostatic Hyperplasia (BPH): Treatment of lower urinary tract symptoms (LUTS) caused by BPH, including urinary frequency, urgency, nocturia, weak urine stream, and incomplete bladder emptying.
• Ureteral Smooth Muscle Relaxation: Off-label use for facilitating ureteral stone passage and relieving ureteral spasms.
• Other Non-Neurogenic Lower Urinary Tract Symptoms: Management of LUTS associated with bladder outlet obstruction.

Adults:

• Recommended oral dose: 50 mg once daily, taken after meals.
• Depending on clinical response and tolerability, the dose may be increased to 75 mg once daily.
• Treatment duration is usually long-term, with regular clinical reassessment.

Elderly:

• Use the same dose as adults. Monitor closely for side effects such as hypotension or dizziness.

Pediatrics:

• Safety and efficacy have not been established; not recommended.

Renal and Hepatic Impairment:

• Use with caution in mild to moderate impairment.
• Avoid in severe hepatic dysfunction due to limited safety data.

Route of Administration:

• Oral tablets, taken with or after food to minimize gastrointestinal discomfort.

Naftopidil is a selective alpha-1 adrenergic receptor antagonist, showing high affinity for α1D- and α1A-adrenoceptors predominantly found in the prostate, bladder neck, and urethra. By blocking these receptors, naftopidil induces relaxation of smooth muscles in these regions, reducing urethral resistance and improving urinary flow. Additionally, blockade of α1D-adrenoceptors in the bladder detrusor muscle and spinal cord may alleviate irritative urinary symptoms such as urgency and frequency.

• Absorption: Rapid and well absorbed orally; peak plasma concentrations occur within 1 to 2 hours post-dose.
• Bioavailability: Moderate, influenced by first-pass hepatic metabolism.
• Distribution: Widely distributed; plasma protein binding approximately 98%.
• Metabolism: Extensively metabolized in the liver via cytochrome P450 enzymes.
• Half-life: Approximately 5 to 8 hours.
• Elimination: Excreted primarily through urine and feces as metabolites.

• Pregnancy: Not indicated for use in pregnant women; no well-controlled studies. Use only if clearly necessary.
• Lactation: Data are insufficient. Due to unknown excretion in breast milk and lack of safety data, use with caution in nursing mothers.

• Primary Class: Alpha-1 adrenergic receptor antagonist.
• Subclass: Selective α1D- and α1A-adrenoceptor blocker.

• Known hypersensitivity to naftopidil or any excipients in the formulation.
• Severe hepatic impairment.
• Severe hypotension or history of orthostatic hypotension.

• Risk of hypotension and orthostatic hypotension, particularly after the first dose. Monitor blood pressure closely.
• Use caution in patients with cardiovascular disease or those on antihypertensive therapy.
• May cause dizziness or syncope, especially in elderly patients.
• Monitor for allergic reactions.
• Use cautiously in hepatic and renal impairment.

Common:

• Dizziness and lightheadedness.
• Headache.
• Fatigue.
• Nasal congestion.
• Palpitations.

Rare but Serious:

• Syncope due to hypotension.
• Allergic reactions such as rash or angioedema.
• Elevation of liver enzymes.

• Additive hypotensive effects with antihypertensive agents or other alpha-blockers.
• Metabolism may be affected by CYP450 inhibitors or inducers, altering plasma concentrations.
• Caution with phosphodiesterase inhibitors due to risk of hypotension.
• Avoid concomitant use with other vasodilators unless under close medical supervision.

• No major recent changes in indications or dosing from regulatory authorities.
• Clinical guidelines recognize naftopidil as an effective selective alpha-blocker for LUTS/BPH with a favorable safety profile.
• Emphasis on monitoring blood pressure during initiation and dose adjustments.

• Store at 20°C to 25°C (68°F to 77°F).
• Protect from light and moisture.
• Keep the container tightly closed.
• Do not freeze.
• Keep out of reach of children.