finasteride: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
finasteride: clinical details
Prescribing considerations
- Discuss psychiatric and sexual adverse effects before prescribing and provide the pack alert card and leaflet.
- Review any history of depression or suicidal ideation and reassess psychiatric and sexual symptoms during treatment.
- Assess other causes of lower urinary tract symptoms and closely supervise patients with substantial residual urine or markedly reduced urinary flow.
- Finasteride alters PSA interpretation and does not exclude coexisting prostate cancer.
- Ask about fertility plans where relevant; poor seminal quality and infertility have been reported, with improvement after discontinuation in some cases.
Contraindications and cautions
- Hypersensitivity to finasteride or product excipients.
- Use during pregnancy; selected products are not indicated for women or children.
- Do not use the hair-loss formulation alongside another finasteride product or another 5-alpha-reductase inhibitor.
- Check product excipients in patients with relevant hereditary disorders of galactose or lactose handling.
- Use caution in hepatic impairment because pharmacokinetic data are limited.
Monitoring
- Monitor for depression, suicidal ideation, mood changes and sexual dysfunction.
- For prostate disease, assess symptoms, urinary flow or residual urine as clinically appropriate and reconsider obstruction requiring intervention.
- Interpret PSA in the context of finasteride-associated suppression and investigate sustained rises from the treated baseline.
- Advise prompt assessment of breast lumps, pain, enlargement or nipple discharge.
Clinical pharmacology
Finasteride competitively inhibits type II 5-alpha-reductase, lowering serum and tissue DHT without binding to the androgen receptor. It is metabolised mainly through CYP3A4 and has active metabolites with much weaker enzyme-inhibitory activity.
Formulation and product differences
- The selected hair-loss product is a 1 mg film-coated tablet licensed for men with androgenetic alopecia.
- The selected prostate product is a 5 mg film-coated tablet licensed for benign prostatic hyperplasia with an enlarged prostate.
- Tablet appearance, excipients and pack presentation are product-specific; check the current product information and packaging.
- Film coating limits contact with finasteride during normal handling if the tablet is not broken or crushed.
finasteride preparations and strengths
Tablet
Route: Oral
Strengths: 1 mg, 5 mg
finasteride interactions
Clinically important medicine interactions are uncommon, but these points matter:
Other finasteride products or dutasteride
Do not duplicate 5-alpha-reductase inhibitor treatment unless specifically directed by a specialist.
Strong CYP3A4 inhibitors or inducers
They may alter finasteride concentrations, although product information considers a clinically important effect unlikely within established safety margins.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.