RÉSUMÉ
Objective:To establish the drug release determination conditions and method for methylphenidate hydrochloride bipolar controlled release osmotic pump tablets. Methods: The drug release of the tablets was determined by HPLC using a Diamonsil C18 (250 mm × 4. 6 mm, 5 μm) column with acetonitrile-KH2 PO4 (0. 02 mol·L-1 ,and pH was adjusted to 3. 0 by 1% H3 PO4 solution) (30∶ 70) as the mobile phase at a flow rate of 1 ml·min-1 , the column temperature was 35 ℃ and the injection volume was 20 μl. The effects of release medium, release apparatus and rotation speed on the release of methylphenidate hydrochloride bipolar controlled release osmotic pump tablets were studied as well. Results:The established drug release determination method had a good linear rela-tionship within the range of 1. 0-24. 0 μg·ml-1(r=0. 999 5), and the average recovery was 100. 5%(RSD=1. 58%, n = 6). Un-der the conditions of 900 ml pH 3. 0 phosphate buffer solution as the release medium and the rotation speed of 50 r·min-1 , the drug was quickly released in 0-2h, and then the release behavior was complied with a zero-level model in vitro in 2-10h with the release e-quation of Q=5. 505t+44. 221(r=0. 994 5). Conclusion:The method is simple, accurate and reliable, and suitable for the quality control of methylphenidate hydrochloride bipolar controlled release osmotic pump tablets.