June 30, 2000 (Washington) -- Of the 30 million American men suffering from erectile dysfunction, those expecting to have an alternative to Viagra soon will now have to wait. The approval application for the erectile dysfunction drug Uprima (apomorphine) was withdrawn by its maker Friday -- just days before the FDA was to render a final decision and despite data demonstrating it might prove to be a safer alternative for patients with heart disease.
Apomorphine has been used to treat various disorders since 1869. For the last half of the 20th century, it has been used as a sedative, and since 1967 as a treatment for Parkinson's disease. In men suffering from erectile dysfunction, the drug stimulates brain centers involved in sexual response and activates spinal nerves to increase blood flow to erectile tissue.
TAP Pharmaceuticals, a joint venture between Abbott Laboratories of Abbott Park, Ill., and Japan's Takeda Chemical Industries, said it decided to withdraw the application for Uprima so it can complete several ongoing studies to confirm the drug's safety and effectiveness. The FDA nod initially was expected in July based on advice from a FDA expert advisory committee, which in April voted 9-3 to recommend that agency officials proceed with its approval.
The FDA committee supported approval of Uprima despite the potential for serious side effects when it is taken with nitrates, a common drug for heart disease, and its apparent interaction with alcohol, which could lead to dangerously low blood pressure, a slow heart rate, and fainting. Viagra also can cause adverse reactions when taken with nitrates. The committee also voted for approval despite questions regarding the overall effectiveness of Uprima. These questions center on whether the clinical trials of the drug truly included men with severe sexual dysfunction.
In those clinical trials, more than half of the treatment group achieved an erection compared with 35% of those patients on placebo. The relatively high rate of responders in the placebo group suggests that the patients included in the studies may not have suffered from severe sexual dysfunction, a number of committee members noted.
Eugene Dula, MD, a urologist and director of West Coast Clinical Research in Van Nuys, Calif., tells WebMD that erectile dysfunction is associated with a high placebo response, and as a result, concerns regarding whether it was tested in the right patient population are probably unfounded.
When asked why the committee voted to support approval in spite of the potential for serious side effects and questions about effectiveness, FDA Committee Chair Ricardo Azziz, MD, MPH, told WebMD, "[Erectile dysfunction] is a major quality of life issue."
Now experts speculate the company withdrew its application because of chances that the FDA might not follow its committee's recommendations to approve the drug. Whatever the outcome, Uprima's interactions with nitrates and alcohol are risks that need serious consideration, Marianne Mann, MD, a deputy director for the FDA, told committee members at the April meeting.
But the delay does not necessarily mean Uprima will not eventually be approved. "We are still very confident [that Uprima is a safe and effective drug]. We hope by taking this extra time we will have a much a stronger product," Kim Modroy, a spokesperson for TAP Pharmaceuticals, tells WebMD.
The additional trials now underway include a large, placebo-controlled study to determine safety and effectiveness in doses ranging from 2 mg to 4 mg, and a smaller placebo-controlled trial to study 3 mg and 4 mg doses. Earlier trials tested a 5 mg dose. The additional trials also include studies to assess how the drug interacts with alcohol and nitrates.
These new studies should answer any of the agency's concerns, notes Dula, who has participated in a number of studies of Uprima.
Modroy says that the company expects to finish these studies sometime this summer and that over the next few weeks, TAP also plans to discuss with FDA officials a new timetable for Uprima's review.
"It is important with Uprima, as with any other drug, that the patient be counseled. It's not candy," he tells WebMD. However, with appropriate follow-up, "I think both Uprima and Viagra are safe and effective first-line treatments."
In previous clinical trials submitted for Uprima's approval, commons side effects included nausea (32%), dizziness (15%), and sweating. About 60% of the participants dropped out due to these side effects, but the majority of these patients were taking a 5 mg dose, which is a dosing regimen that TAP says it has no plans to pursue. If it is eventually approved, Uprima will be sold in doses ranging from 2 mg to 4 mg, the company says.