Extended-Release Matrix Tablets of Tramadol Using Hydroxypropyl Methylcellulose Blends

Tramadol hydrochloride is a freely soluble opioid analgesic with a short half-life, which makes it a natural candidate for once- or twice-daily extended-release tablets. This review summarises published work on hydroxypropyl methylcellulose (HPMC) matrix systems and their use for tramadol, and it reports no new data. It covers the pharmacology that motivates modified release, the gel-layer mechanism of HPMC matrices, the influence of polymer grade, level, blending and diluents, and the dissolution testing and kinetic models used to judge performance. Published evidence shows that viscosity grade and polymer ratio can tune release predictably, whereas reporting of in vivo correlation, alcohol sensitivity and tablet robustness is limited.