Hypromellose (HPMC) is a water-soluble hydrophilic, non-ionic cellulose ether.

Hypromellose (hydroxypropylmethylcellulose) is a long-established component of sustained-release pharmaceutical formulations. In matrix tablets, this polymer rapidly absorbs water, forming a viscous gel barrier that encapsulates the tablet. The modulation of drug release rates by hypromellose is governed by several factors, including the water diffusion rate into the polymer, the kinetics of hypromellose hydration and subsequent gelation, the viscosity of the gel produced, and the erosion rate of the gel layer [2]. This mechanism enables hypromellose to facilitate a controlled drug release, extending the drug's therapeutic efficacy [1].

Punctal occlusion using hypromellose 2% is a low-cost and safe additional treatment for dry eye, significantly reducing symptoms as indicated by fluorescein and rose bengal staining tests [3]. Hypromellose also improves blood glucose metabolism and suppresses oxidative stress in mice on a high-fat diet, likely through the regulation of hepatic glucose-regulating enzyme activities and activation of hepatic and erythrocyte antioxidant enzymes [4].