Prozac Weekly - Brief Article

0 Comments | Family Practice News, April 15, 2001 | by Elizabeth Mechcatie

(fluoxetine, Eli Lilly)

A delayed-release formulation of the selective serotonin reuptake inhibitor for once-weekly dosing, after a patient has achieved an initial antidepressant response with the daily formulation.

* Recommended Dosage: One 90-mg capsule once a week on the same day, started after 13 weeks of acute therapy with 20 mg fluoxetine daily, 7 days after the last 20-mg dose is taken.

* Special Considerations: In a study comparing the 20-mg daily dose and the 90-mg weekly dose with placebo, the most common side effects were nervousness (13.7% of subjects), headache (10.5%), asthenia (9.5%), and diarrhea (9.5%) among those on Prozac Weekly vs. 3%, 12.2%, 9.5%, and 4.8%, respectively, among those on the daily dose, according to Lilly. The sexual dysfunction rate was similar with the daily and weekly doses but was higher in the placebo group because of worsening depression, said Dr. Mark E. Schmidt, senior clinical research clinician at Lilly.

* Comment: The study enrolled patients aged 18-80 diagnosed with major depression; they were treated with 20 mg of Prozac daily for up to 13 weeks. The 501 patients who responded were randomized to continue the 20-mg formulation, switch to 90 mg once a week, or receive a placebo. The relapse rate during the next 25 weeks was 37% with weekly Prozac, 26% with daily Prozac, and 50% with placebo.

The difference in relapse rates between the two Prozac groups was not significant, Dr. Schmidt said during a Lilly-sponsored teleconference. The drug's labeling says that the equivalence of the two treatments during continuation therapy "has not been established" and advises that if weekly fluoxetine is not effective, "consider reestablishing a daily dosing regimen."

When asked if a person stabilized on 40 mg of Prozac a day could switch to the 90-mg formulation twice a week, Dr. Schmidt said that Lilly has not formally tested this regimen, but in his personal opinion, that "would be reasonable." Labeling of the immediate-release formulation allows up to 80 mg a day, he noted. A patient who forgets to take a dose can take the missed dose up to 24 hours before the next dose is due, and he should not revise the schedule.