Prozac, Weakly
A Journal Article Finds Shortcomings in the New Version of the Popular Antidepressant
Tuesday, June 12, 2001; Page HE07
Eli Lilly's ad campaign to convert some satisfied Prozac users to a new once-a-week formulation is being greeted with caution by the Medical Letter on Drugs and Therapeutics, an independent, peer-reviewed journal for doctors.
Lilly's drive, which encourages current Prozac users to discuss the switch to the weekly pill with their doctors, comes in the months before its patent on Prozac, the best-selling antidepressant, expires. Lower-priced generic versions of Prozac are expected to hit the market in August.
A recent article in the Medical Letter pointed to data from company-sponsored clinical trials in which 501 patients were given Prozac Weekly, the daily version or a placebo. The article pointed out that those patients who were given the weekly form experienced diarrhea and cognitive problems more often than patients given the daily form. It said 37 percent of patients taking the weekly form experienced a relapse of depression symptoms, compared with 26 percent of patients taking the daily dose and 50 percent of patients taking a placebo.
The publication also said dosing may be difficult. The 90 mg weekly pill is intended only for patients who are taking 20 mg of the daily pill. Some patients take as little as 10 mg or as much as 80 mg per day. It also questioned whether patients would remember to take the drug once a week. "More studies are needed to determine whether once-weekly [Prozac] is as effective and safe as taking smaller doses of the drug once daily," it concluded.
Eli Lilly calls Prozac Weekly an excellent alternative for most patients and disputes the Medical Letter's conclusions.
Lilly says patients on a weekly schedule are more likely to remember to take their medicine. "People have shown that they will stick with their therapy with Prozac Weekly better than they would with Prozac daily," says John Plewes, a clinical research physician at Lilly. A company-sponsored study found that compliance rates for weekly- and daily-dose patients were 86 percent and 79 percent, respectively.
Plewes says the difference in relapse rates between the weekly and daily dose groups was not statistically significant. Although more patients on the weekly formulation complained of nervousness and thinking problems, he says, they complained no more often than did patients taking a placebo.
He says that although weekly-dose patients complained of diarrhea more frequently than did daily-dose patients, none cited diarrhea as a reason for dropping out of the trials. Besides, he says, when these patients were asked a second time, there was no difference. As for dosing, Plewes says about 80 percent of Prozac patients currently take the 20 mg daily dose that corresponds with the weekly pill's dose.
Competitors may begin to market generic forms of Prozac -- but not Prozac Weekly -- as early as August, when Lilly's patent for the drug expires. Lilly holds exclusive marketing rights to Prozac Weekly until 2004.
When the Food and Drug Administration (FDA) determined in February that Prozac Weekly was safe and effective, it withheld judgment on the comparative efficacy of the daily and weekly treatments. The agency is requiring Lilly to say in its labeling for the new product that "it is unknown whether or not Prozac Weekly given on a once-weekly basis provides the same level of protection from relapse as that provided by Prozac 20 mg daily." The FDA also ordered Lilly to disclose that in clinical trials more weekly users experienced diarrhea.
A recent newspaper ad for Prozac Weekly says side effects for the two treatments are similar, and it lists diarrhea as one of more than 25 side effects but it does not point out any difference in diarrhea rates despite FDA regulations mandating presentation of all material facts with respect to consequences of taking the drug as suggested. The ad also fails to reveal that the two forms may not be equivalent in terms of efficacy. "You try to make it understandable for people," Plewes says.
Another Lilly spokesman says the company's goal with its ads is partly to educate patients but also to encourage them to discuss a switch of medication with their doctor.
