Clinical fit and expected benefit: With a prostate volume of approximately 106 mL, he falls within the group with a large prostate at increased risk of BPH progression for whom a 5-alpha-reductase inhibitor is appropriate as long-term disease-modifying treatment. NICE CKS
Finasteride 5 mg once daily and dutasteride 500 micrograms once daily are considered equally effective for LUTS associated with BPH in men with larger prostates, have similar adverse-effect profiles, and may take up to 6 months to provide a beneficial response. NICE CKS
Across 2–4 years, 5-alpha-reductase inhibitors improve IPSS by approximately 15–30% and reduce prostate volume by 18–28%; finasteride trial data showed approximately 20% sustained volume regression, improved urinary flow, and a 2-point symptom-score improvement. NICE CKS SmPC Finasteride
Finasteride reduced acute urinary retention from 7 to 3 per 100 men and BPH surgery from 10 to 5 per 100 men over four years. SmPC Finasteride
In MTOPS, finasteride reduced clinical BPH progression by 34% and acute urinary retention by 67% versus placebo; combination with doxazosin reduced clinical progression by 67% and acute retention by 79%. SmPC Finasteride
Finasteride versus dutasteride: The supplied NICE evidence does not establish a clinically meaningful efficacy advantage of dutasteride over finasteride for LUTS relief in men with large prostates. NICE CKS
Adverse effects shared by both drugs: Potential adverse effects include erectile dysfunction/impotence, reduced libido, ejaculatory disorder, and breast disorders. NICE CKS
He should promptly report breast lumps, pain, or nipple discharge because breast cancer has been reported rarely. NICE CKS
Additional reported effects: Dutasteride may cause alopecia or hypertrichosis uncommonly, with angioedema, depression, hypersensitivity or skin reactions, localised oedema, and testicular disorders reported at unknown frequency. NICE CKS
Finasteride may cause skin reactions uncommonly, with angioedema, depression, male infertility, palpitations, and testicular pain reported at unknown frequency. NICE CKS
Depression has been associated with finasteride for BPH, and finasteride should be stopped with prompt clinical review if depression develops. NICE CKS
PSA and cancer-assessment implications: PSA 5.4 ng/mL and prostate cancer assessment require review before starting either drug, including digital rectal examination and other appropriate evaluations, with periodic reassessment thereafter. NICE CKS
After 6 months, either drug lowers mean PSA by approximately 50%; establish a new PSA baseline at 6 months and monitor PSA regularly thereafter. NICE CKS
Any confirmed PSA rise from the on-treatment nadir warrants evaluation for prostate cancer or non-adherence, even if the value remains within the usual reference range for men not taking a 5-alpha-reductase inhibitor. NICE CKS
Cardiovascular considerations: The supplied guidance identifies palpitations as a reported adverse effect of finasteride but does not identify atrial fibrillation or medically controlled hypertension as a specific contraindication to either finasteride or dutasteride. NICE CKS
If considering alpha-blocker combination treatment because of substantial symptoms or progression risk, recognise that combination therapy increases sexual adverse effects versus alpha-blocker monotherapy. NICE CKS
Practical choice: On the evidence provided, either agent is reasonable for the large gland, but finasteride has a specifically reported potential for palpitations whereas dutasteride does not in this source; shared sexual, breast, mood, and PSA-monitoring issues should drive informed choice and follow-up. NICE CKS