dutasteride (doo-tas-te-ride) Avodart

 Indications

Management of the symptoms of benign prostatic hyperplasia

(BPH) in men with an enlarged prostate

gland (alone or with tamsulosin).

Action

Inhibits the enzyme 5-alpha-reductase, which is responsible

for converting testosterone to its potent metabolite

5-alpha-dihydrotestosterone in the prostate

gland and other tissues. 5-Alpha-dihydrotestosterone is

partly responsible for prostatic hyperplasia. Therapeutic

Effects: Reduced prostate size with associated

decrease in urinary symptoms.

Pharmacokinetics

Absorption: Well absorbed (60%) following oral

administration; also absorbed through skin.

Distribution: 11.5% of serum concentration partitions

into semen.

Protein Binding: 99% bound to albumin; 96.6%

bound to alpha-1 glycoprotein.

Metabolism and Excretion: Mostly metabolized

by the liver via the CYP3A4 metabolic pathway; metabolites

are excreted in feces.

Half-life: 5 wk.

TIME/ACTION PROFILE (reduction in

dihydrotestosterone levels†)

ROUTE ONSET PEAK DURATION

PO unknown 1–2 wk unknown

†Symptoms may only improve over 3–12 mo.

Contraindications/Precautions

Contraindicated in: Hypersensitivity; Cross-sensitivity

with other 5-alpha-reductase inhibitors may occur;

Women; Pedi: Children.

Use Cautiously in: Hepatic impairment.

Adverse Reactions/Side Effects

CNS: depressed mood. GU: PROSTATE CANCER (highgrade),

plibido, ejaculation disorders, erectile dysfunction,

testicular pain, testicular swelling. Endo:

gynecomastia. Derm: rash, urticaria. Misc: ALLERGIC

REACTIONS, ANGIOEDEMA.

Interactions

Drug-Drug: Blood levels and effects may beqby ritonavir,

ketoconazole, verapamil, diltiazem, cimetidine,

ciprofloxacin, or other CYP3A4 enzyme

inhibitors.

Route/Dosage

PO (Adults): 0.5 mg once daily (with or without tamsulosin).

Availability (generic available)

Soft gelatin capsules: 0.5 mg. In combination

with: tamsulosin (Jalyn); see Appendix B.