FDA Approves Drug Treatment for Benign Prostatic Hyperplasia

Urologic Agents Avodart (dutasteride) capsules

Manufacturer: GlaxoSmithKline

Drug Approval Classification: Supplemental New Drug Application (Approval Date: 10/9/02)

Indication:Avodart (dutasteride) is indicated for the treatment of symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate to do the following:

* Improve symptoms
* Reduce the risk of acute urinary retention
* Reduce the need for BPH-related surgery

Dosing:Avodart recommended dosing is 1 capsule (0.5 mg) taken orally once daily. Avodart may be taken with or without food.

No dosage adjustment is necessary for patients with renal impairment or in elderly patients.

There are no data on the effects of Avodart in patients with hepatic impairment.

Clinical Summary: Dutasteride is a synthetic 4-azasteroid compound that is a selective inhibitor of both the type 1 and type 2 isoforms of steroid 5alpha-reductase, an intracellular enzyme that converts testosterone to 5alpha-dihydrotestosterone.

Three 2-year, multicenter, placebo-controlled, double-blind studies of more than 4000 male patients with BPH evaluated dutasteride, 0.5 mg/day, vs placebo. Compared with placebo, Avodart was associated with a lower incidence of acute urinary retention (1.8% for Avodart vs 4.2% for placebo, P<.001 and with a significantly lower incidence of surgery for avodart vs placebo p .001>
Adverse Effects: The most common adverse events were related to reproductive system effects (impotence, decreased libido, ejaculation disorder, and gynecomastia [Breast growth]).

Pharmacokinetics: Cmax of dutasteride occurs within 2-3 hours after administration. Dutasteride is highly bound to plasma albumin (99.0%) and alpha-1 acid glycoprotein (96.6%). Dutasteride is metabolized by the CYP3A4 isoenzyme to 2 minor monohydroxylated metabolites. The terminal elimination half-life is approximately 5 weeks at steady state; serum concentrations are detectable for up to 4-6 months after discontinuation of therapy.

Drug interaction studies with inhibitors of CYP3A4, such as ritonavir, ketoconazole, verapamil, diltiazem, cimetidine, and ciprofloxacin, have not been performed.

Reference: Avodart (dutasteride) capsules labeling