Cancer therapy
Antimetabolite chemotherapy
5-Fluorouracil (chronomodulated)
Also known as: 5-FU infusion
Best time
Overnight infusion, peak ~04:00
- 22:00–10:00· Infusion, peak delivery ~04:00
In chronotherapy protocols, 5-FU is infused overnight with peak delivery around 04:00.
Emerging evidence
Promising early or observational research — not yet standard practice everywhere.
Why this time works
The enzyme that breaks down 5-FU (DPD) is most active at night, and healthy gut and bone-marrow cells divide least then. Programmable pumps deliver most of the drug around 04:00, which in trials reduced side effects like mouth sores; survival benefit varied by patient group, including sex.
Body rhythm involved
Healthy cell division in gut and bone marrow is lowest at night; DPD activity peaks at night.