Viadur (leuprolide acetate implant)

Viadur is a testosterone suppression therapy for the palliative treatment of advanced prostate cancer. In an in-office procedure, the product is implanted under the skin under the upper arm of the patient, and using the DUROS implant technology, Viadur delivers continuous, osmotically-driven treatment for an entire year. This product is the first to deliver 12 months of testosterone suppression therapy in a single administration. Previous hormone treatments for patients with advanced prostate cancer involved intramuscular depot injections administered every several months.

The active ingredient of the therapy is leuprolide, a luteinizing hormone-releasing hormone (LH-RH) agonist, which lowers levels of the male hormone testosterone. This hormone suppression is associated with pain relief in some advanced prostate cancer patients. Leuprolide is continuously delivered in the appropriate dose for the full year by an osmotic engine . After 12 months, the implant may be removed and replaced with a second implant to provide the therapy for a second year.

Prostate Cancer affects approximately one in eight American men and is the second most fatal cancer for men in the U.S. The testosterone suppression therapy is an important long-term palliative treatment for the advanced stages of prostate cancer.

A two-year study was conducted for 131 men with advanced prostate cancer who received the Viadur treatment. By the fourth week after the initial insertion of the implant, 99% of the patients had mean serum testosterone concentrations at desirably lower levels than those previous to the treatment. Furthermore, the testosterone suppression continued throughout the duration of the entire year-long treatment. 118 of the patients had a second implant inserted for a second year of therapy following the removal of the first implant. No patient experienced a significant increase in serum testosterone after the insertion of a new implant.

The most common side effects were:

• Vasodilation (experienced by 67.9% of patients)
• Asthenia (7.6%)
• Gynecomastia (6.9%)
• Depression (5.3%)
• Sweating (5.3%)

The above side effects are expected with all LH-RH agonists.

The insertion and removal of the implants caused bruising and burning to the local application site in 34.8% and 5.6% of the patients, respectively. These reactions mostly lasted for approximately two weeks following the insertion or removal of an implant. 9.3% of patients had bruising and/or burning that persisted, and 10% of patients developed reactions after the first two weeks following insertion.

During the first week of treatment, there is a transient increase in serum concentrations of testosterone, which may cause pain or bladder outlet obstruction. This was experienced in 4.6% of patients in clinical studies.

Leuprolide acetate, an LH-RH agonist, acts as a potent inhibitor of gonadotropin secretion when given continuously and in therapeutic doses…
In humans, administration of leuprolide acetate results in an initial increase in circulating levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), leading to transient increase in concentrations of gonadal steroids (testosterone and dihydrotestosterone in males…). However, continuous administration of leuprolide acetate results in decreased levels in LH and FSH. In males, testosterone is reduced to castrate levels. These decreases occur within 2 to 4 weeks after initiation of treatment.
One Viadur Implant nominally delivers 120 micrograms of leuprolide acetate per day over 12 months. Leuprolide acetate is not active when given orally. (From FDA Label)

Visit the Ortho-MCNeil web site, www.ortho-mcneil.com, to learn more about Viadur and about other products, research, and services provided by the company that developed this drug.

For more information about prostate cancer and research being done in this field, visit:

• the Prostate Cancer Research Institute web site, www.prostate-cancer.org.
  and
• the American Cancer Society home page, www.cancer.org