Testosterone gel shows promise in Phase III trial

Research shows gel works as well as patch

Clinicians looking for a way to raise HIV-infected men’s testosterone levels may soon be able to prescribe the hormone in the form of a gel that can be easily administered.

Early results from a phase III, multicenter, comparative clinical trial show that Androgel, a testosterone replacement gel developed by Unimed Pharmaceuticals of Buffalo Grove, IL, effectively restores testosterone serum levels. The results also show that the gel causes no skin irritation.

"With transdermal gel delivery, quite adequate levels of testosterone are delivered in a patient-friendly manner," says Ronald S. Swerdloff, MD, principal investigator for the clinical trials. Swerdloff is a professor of medicine at the Uni versity of California at Los Angeles and chief of endocrinology at the Harbor-UCLA Medical Center in Torrance, CA.

Unimed’s multicenter study is evaluating 227 men, ages 18 to 68, who have been diagnosed with hypogonadism. Men were randomly assigned to apply either one or two doses of Androgel each day or to wear a testosterone patch. They are being monitored for 180 days, with primary monitoring points at 30 and 90 days.

The study has not targeted AIDS patients, but recent research has shown that testosterone-replacement therapy helps HIV-infected men regain muscle mass and improve physically and mentally. (See story on testosterone therapy in the February 1999 issue of AIDS Alert.)

A gel application has several big advantages, Swerdloff says. First, patients can easily apply it themselves, requiring fewer clinic visits. Also, it can be used confidentially, unlike a patch, which may be noticed by the patients’ colleagues and friends. And clinicians can adjust the dose easily according to what the patient needs.

The gel, which dries rapidly and leaves no residue on the skin, is rubbed on the shoulders, abdomen, or chest.

Gel testosterone easy to dose

"It’s easy to dose because it depends on how much you apply," Swerdloff says. The clinical trials are using bottles with a fixed amount of gel per squirt. But Androgel will be marketed in individual dosage packages of 25 mg that allow a wide range of application doses. Clinicians could prescribe two- to four-package doses.

"The gel gives fairly constant levels throughout the day, so there’s not a lot of variation," Swerdloff adds.

Preliminary trial results indicate that a once-daily application of Androgel raised circulating testosterone levels to desirable levels at all evaluation time points. Patients sustained these levels throughout the 90-day treatment phase. The study also will evaluate serum testosterone levels after 180 days of continuous treatment.

"The results are highly favorable on all parameters that were looked at," Swerdloff says. "The gel seems to give responses that are at least comparable to any other male hormone preparation on all the different parameters, such as libido, lean body mass, muscle strength, bone mineral markers, and body fat."

Europeans have administered androgens in a gel form for more than 15 years, but this will be the first such product available in the United States. Unimed plans to submit the gel this year to the Rockville, MD-based Food and Drug Administration (FDA) for review.