Relative bioavailability and pharmacokinetics of two oral formulations of docosahexaenoic acid/eicosapentaenoic acid after multiple-dose administration in healthy volunteers

To assess the comparative pharmacokinetic profile and bioavailability of docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) after multiple-dose administration of a new oral formulation (test formulation) and a commercially available reference formulation in healthy subjects. Forty-eight healthy subjects received a 28-day oral treatment with DHA/EPA in the form of either the test or the reference product according to an open-label, randomized, parallel-group design. Both formulations were given t.i.d. at 8-h intervals at a dose of 3.0 g/day. Steady-state DHA and EPA concentrations in plasma and lysed whole blood were measured by gas-liquid chromatography at baseline and after 7, 14, 21 and 28 days of treatment. Kinetic parameters were compared both after subtraction of baseline concentrations and by using baseline concentrations as a covariate. For both DHA and EPA, plasma and RBC concentrations measured from day 7 to day 28 were significantly higher than at baseline and did not differ significantly between the two products. On day 28 the plasma DHA concentration on average doubled the baseline level after administration of test and reference product, while there was a 10-fold increase in EPA plasma concentration. When the assessment was performed using baseline values as covariate, test-to-reference ratios for area under the curve (AUCss(0-8)) and for peak concentration (Css(max)) after the last administration on day 28 met bioequivalence criteria (i.e., 90% confidence intervals within 0.80-1.25 for AUCss(0-8) ratios, and within 0.75-1.33 for Css(max) ratios). When the assessment was conducted after subtraction of baseline values, the 90% confidence intervals for Css(max) ratios were within the bioequivalence range, whereas the intervals for AUCss(0-8) ratio were borderline for bioequivalence. The two formulations tested were similarly effective in increasing DHA and EPA concentrations in plasma and lysed whole blood, and showed comparable bioavailability for both active components.