Assessment of the Pharmacopeial Analytical Methodologies in the Dissolution Test of Enteric-Coated Lansoprazole Preparations

The performance of the analytical methodologies recommended by the United States Pharmacopoeia (USP) monograph (1) for dissolution testing of lansoprazole (LPZ) enteric-coated solid dosage forms (capsules/tablets) was critically evaluated. While USP adopts an essentially nonselective UV method, the British Pharmacopoeia (2) recommends a highperformance liquid chromatography (HPLC) method capable of separating the drug from its acid degradation products. For an acid-labile drug such as LPZ, one might think that the nonselective UV method might overor underestimate the percentage released because the degradation product might have UV absorptivity different from that of the parent drug. We subjected six commercial products in addition to the reference product (G) to analysis according to the USP assay and dissolution recommendations. Products were also subjected to dissolution tests whereby a selective HPLC method was employed for quantifying the percentage release. All products passed USP assay tests. For dissolution, the UV method adopted by USP was more reliable because it indicated the actual percentage released compared with the selective HPLC method, which reflected only the percentage of released LPZ that remained intact (undegraded). Only one product (E) failed to satisfy the USP requirements for dissolution.