Development and validation of a dissolution test method for vitamin A in dietary supplement tablets.

A dissolution test method and an analytical procedure by HPLC were developed and validated for evaluation of the dissolution behavior of dietary supplements tablets containing vitamin A in the forms of retinyl acetate or retinyl palmitate. Seven different commercially available products containing retinyl acetate or retinyl palmitate were selected for this study. A dissolution medium containing 1% (w/v) Octoxynol 9 (Triton X-100) and 1% (w/v) (+)-sodium alpha-ascorbate in 0.05 M phosphate buffer, pH 6.8, was found suitable to ensure sink conditions and chemical stability for both retinyl acetate and retinyl palmitate. Two rotation speeds, 50 and 75 rpm, were evaluated with USP Apparatus 2 and 900 ml dissolution medium. Dissolution profiles were generated over 120 min. Dissolution samples were analyzed with a reversed-phase HPLC method with UV detection at 325 nm. Each product was also assayed for vitamin A content according to USP 32-NF 27. The results from 45 min to the last time point of the dissolution tests performed at 75 rpm were consistent with the Assay results. The dissolution test described here could be proposed as a pharmacopeial standard to assess the performance of tablet formulations containing vitamin A as retinyl esters.