Sequential drug delivery for liver diseases

The liver performs critical physiological functions such as metabolism/detoxification and blood homeostasis/biliary excretion. A high degree of blood access means that a drug's resident time in any cell is relatively short. This short drug exposure to cells requires local sequential delivery of multiple drugs for optimal efficacy, potency, and safety. The high metabolism and excretion of drugs also impose both technical challenges and opportunities to sequential drug delivery. This review provides an overview of the sequential events in liver regeneration and the related liver diseases. Using selected examples of liver cancer, hepatitis B viral infection, fatty liver diseases, and drug-induced liver injury, we highlight efforts made for the sequential delivery of small and macromolecular drugs through different biomaterials, cells, and microdevice-based delivery platforms that allow fast delivery kinetics and rapid drug switching. As this is a nascent area of development, we extrapolate and compare the results with other sequential drug delivery studies to suggest possible application in liver diseases, wherever appropriate.