New Strategies to Improve Drug Solubility and Its Impact on Bioavailability: A Patent Review (2015-2024)

Poor aqueous solubility is a major barrier in drug development, affecting dissolution, absorption, and systemic bioavailability. Nearly 40% of approved drugs and up to 90% of new chemical entities face this limitation, resulting in therapeutic inefficacy and costly clinical development. This study reviewed patents published between 2015 and 2024 that describe technological strategies to enhance drug solubility and bioavailability, aiming to identify innovation trends and their pharmaceutical impact. A structured search was conducted in the Espacenet database using the keywords "bioavailability" and "solubility" under the IPC code A61K. From 98,111 initial results, duplicates, language restrictions, and patents related to cosmetics, nutrition, or veterinary products were excluded, yielding 29 eligible documents. Extracted data included applicant country, therapeutic indication, BCS classification, formulation approach, manufacturing method, and available in vivo pharmacokinetic results. Descriptive analysis was performed using R software. China led patent registrations (55%), followed by the USA (17%). Patent filings increased steadily from 2016-2020, decreased during the COVID-19 pandemic, and recovered after 2021. Most drugs belonged to BCS Class II (76%), reflecting high permeability but poor solubility. The main strategies included particle size reduction, solid dispersions, self-emulsifying drug delivery systems, cyclodextrin inclusion complexes, and advanced crystallization techniques. When reported, pharmacokinetic data showed significant improvements in Cmax and AUC; however, only 58% of patents included in vivo studies. Overall, patents reveal robust innovation aimed at overcoming solubility challenges.