FLUOXETINE AND NORFLUOXETINE SERUM CONCENTRATIONS AND CLINICAL-RESPONSE IN WEEKLY VERSUS DAILY DOSING

This study explored serum concentrations of fluoxetine and norfluoxeti ne in subjects treated under different dosing regimens. Using a placeb o-controlled, randomized, double-blind design, we compared 20 mg fluox etine daily, 60 mg fluoxetine weekly, and a placebo. All subjects had responded positively to a 7-week open-label trial of 20 mg fluoxetine daily. Consistent with numerous attempts to correlate fluoxetine and n orfluoxetine blood levels to clinical response, we found no significan t relationships between serum concentrations and Hamilton Rating Scale for Depression (HAM-D) scores. Serum concentrations were significantl y different among the three treatment groups. Pairing the fact that th e serum concentrations of subjects given 60 mg fluoxetine weekly were significantly lower than those given 20 mg daily with the finding that the 60 mg weekly group had lower HAM-D scores suggests that, for stab ilized subjects, this nontraditional dosing strategy is at least as ef fective in treating depression as the standard 20 mg fluoxetine daily treatment.