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doxazosin and finasteride

G04CA55

Forms & Strengths

Fixed-dose combination capsule: Doxazosin 1 mg / Finasteride 5 mg
Fixed-dose combination capsule: Doxazosin 2 mg / Finasteride 5 mg
Fixed-dose combination capsule: Doxazosin 4 mg / Finasteride 5 mg

Adult Dosing

Benign Prostatic Hyperplasia (BPH): 1 capsule (doxazosin/finasteride) orally once daily
Administer approximately 30 minutes after the same meal each day
Titration of doxazosin component may be required prior to initiating combination therapy

Pediatric Dosing

Not indicated for use in pediatric patients
Safety and efficacy in children have not been established

Indications

Treatment of symptomatic benign prostatic hyperplasia (BPH)
Reduction in the risk of acute urinary retention and BPH-related surgery

Mechanism of Action

Doxazosin is a selective alpha-1 adrenergic receptor blocker that relaxes smooth muscle of the bladder neck and prostate
Finasteride is a competitive inhibitor of type II 5-alpha-reductase, preventing conversion of testosterone to dihydrotestosterone (DHT) and shrinking prostate volume

Contraindications

Hypersensitivity to doxazosin, other quinazolines (e.g., prazosin, terazosin), finasteride, or any component of the formulation
History of orthostatic hypotension
Women who are pregnant or may become pregnant (risk of fetal abnormalities)
Pediatric patients

Adverse Reactions

Dizziness
Orthostatic hypotension
Somnolence
Fatigue
Erectile dysfunction
Decreased libido
Ejaculation disorders
Gynecomastia
Floppy iris syndrome during cataract surgery

Drug Interactions

Phosphodiesterase-5 (PDE-5) inhibitors (e.g., sildenafil): Increased risk of symptomatic hypotension
Strong CYP3A4 inhibitors: May increase doxazosin exposure
Antihypertensive agents: Potential for additive blood pressure-lowering effects
CYP3A4 inducers: May decrease doxazosin plasma concentrations

Curated Content: Needs Vetting Before Put to Clinical Use