Hydroxypropyl Cellulose Derived from Sugarcane Bagasse as a Tablet Binder and Drug Delivery Matrix: A Structured Narrative Review of Synthesis, Pharmaceutical Performance, and Sustainability Indicators Relative to Commercial Grades.

Hydroxypropyl cellulose (HPC) is extensively utilized as a binder and in controlled-release matrices, yet its production predominantly relies on high-purity α-cellulose derived from wood or cotton, which subjects supply chains to sustainability issues and fluctuations in feedstock prices. Annually, sugarcane bagasse, estimated at approximately 490-600 million tons annualy, presents a scalable, residue-based cellulose source for HPC production within circular bioeconomy frameworks. This review compiles findings from 106 peer-reviewed studies on cellulose and HPC derived from bagasse, addressing synthesis methods, structure-property relationships, and pharmaceutical applications. Published studies indicate that HPC derived from bagasse can achieve a degree of substitution (DS 1.87) compared to commonly reported commercial wood-pulp HPC grades (DS 1.8-2.5). Crystallinity reduction relative to commercial HPC has been proposed based on the lower crystallinity of the underlying bagasse cellulose feedstock, but this has not yet been directly measured for the hydroxypropylated product. Beyond performance, bagasse is an agricurtural residue available at negligible feedstock cost, in contrast to the established market prices of purified wood pulp and cotton linter (US$18-25 per kg) used in commercial HPC manufacturing. Life-cycle assessments of bagasse valorization pathways have similarly reported favorable environmental profiles relative to conventional biomass feedstocks. However, no dedicated techno-economic or life-cycle assessment specific to pharmaceutical-grade HPC production from bagasse has been published, and these potential sustainability and cost advantages therefore remain to be formally validated at industrial scale. Key challenges remain in regulatory acceptance, impurity control, batch-to-batch standardization, and scaling up etherification under pharmaceutical good manufacturing practice (GMP) constraints. Overall, the reviewed literature positions sugarcane bagasse (SCB)-derived HPC as a promising candidate for combining excipient performance with potential sustainability and cost benefits, necessitating targeted process optimization and qualification studies to expedite industrial adoption.