DUTASTERIDE

DUTASTERIDe (du-tas'ter-ide) Avodart Classifications: antiandrogen; 5-alpha reductase inhibitor; benign prostatic hyperplasia (bph) agent; Therapeutic:bph agent Prototype: Finasteride Pregnancy Category: X

Availability

0.5 mg capsules

Action

Specific inhibitor of the steroid 5-alpha-reductase, an enzyme necessary to convert testosterone into the potent androgen 5-alpha-dihydrotestosterone (DHT) in the prostate gland.

Therapeutic Effect

Decreases the production of testosterone in the prostate gland.

Uses

Treatment of benign prostatic hypertrophy (BPH).

Unlabeled Uses

Treatment of male pattern baldness.

Contraindications

Hypersensitivity to dutasteride or finasteride; pregnancy (category X), lactation, and children <18 y.

Cautious Use

Hepatic impairment, obstructive uropathy.

Route & Dosage

BPH Adult: PO 0.5 mg once daily Male Pattern Baldness Adult: PO 0.25–0.5 mg once daily

Administration

Oral

• Do not handle capsules if you are or may become pregnant because of the potential for absorption of dutasteride and the subsequent risk to a developing male fetus.
• Do not open or crush capsules. They must be swallowed whole.
• Store at 15°–30° C (59°–86° F).

Adverse Effects (≥1%)

Endocrine: Gynecomastia. Urogenital: Ejaculation dysfunction, impotence, decreased libido.

Interactions

Drug: Diltiazem, verapamil may decrease clearance of dutasteride. Herbal: May see exaggerated effects with saw palmetto.

Pharmacokinetics

Absorption: Rapidly absorbed. 60% bioavailability. Peak: 2–3 h. Distribution: 99% protein bound. Metabolism: Metabolized in liver by CYP3A4 to one active and 2 inactive metabolites. Elimination: Primarily in feces. Half-Life: 5 wk.

Nursing Implications

Assessment & Drug Effects

• Monitor voiding patterns, assessing for ease of starting a stream, frequency, and urgency.
• Lab tests: Monitor baseline PSA and again at 3–6 mo to establish new baseline to use to assess potentially cancer-related changes in PSA. After 6 mo of treatment, obtained PSA values should be doubled for comparison with normal values in untreated men.

Patient & Family Education

• Do not donate blood until at least 6 mo following last dose to prevent administration of dutasteride to a pregnant female transfusion recipient.
• Ejaculate volume might be decreased during treatment but this does not seem to interfere with normal sexual function.
• Note that the incidence of most drug-related sexual adverse events (impotence, decreased libido, and ejaculation disorder) typically decrease with duration of treatment.

---

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug