Action: Supresses serum
dihydotestosterone levels by
inhibiting the conversion of
testosterone to
dihydrotestosterone
Uses: Benign prostatic
hyperplasia, androgenic
alopecia (men only),
female hirsutism
Finasteride
Propecia, Prosear
5-Alpha-Reductase Inhibitors
Dosages:
Adult: 1-5 mg q day
A: Bioavail. 65%
Pedi: not indicated
D: Protein bind. 90%
Pregnancy: X
Lactation: contraindicated
M: hepatic CYP3A4
Routes: Oral
Onset: 6 mos (BPH), >3
mos (hair loss)
Peak: 2-6 hrs
Duration: unknown
E: feces (57%), urine (39%)
Half-life: 6 hrs
Common Side Effects: erectile dysfunction, decreased libido, breast enlargement, ejaculation
disorder, breast tenderness, rash
Adverse Effects: hypersensitivity reactions – rash, pruritis, uticaria and angioedema (including
swelling of lips, tongue, throat and face); male breast cancer; depression
Contraindications: hypersensitivity, women of childbearing potential, children
Interactions: carbamazepine, clarithromycin, erythromycin base, erythromycin ethylsuccinate,
erythromycin lactobionate, erythromycin stearate, isoniazid, itraconazole, ketoconazole,
nefazodone, nevirapine, rifabutin, rifampin, St. John’s wort
Nursing Considerations: caution in liver dysfunction; sexual dysfunction continues after
discontinuation of treatment; may cause decreased serum PSA; pregnant and potentially pregnant
women should not handle crushed or broken tablets; report signs of male breast cancer – breast
tenderness, enlargement, pain, lumps, nipple, discharge or any breast changes