Antimetabolite (leukaemia maintenance)

Mercaptopurine

Also known as: Purixan, 6-MP

Best time

Evening, same time daily

18:00–22:00

Traditionally taken in the evening in childhood leukaemia maintenance; newer studies are less certain.

Mixed evidence

Studies disagree. Taking it at the same time every day matters more than the hour.

Why this time works

Older studies linked evening dosing with lower relapse rates in children with ALL, possibly because bone-marrow cells synthesise DNA more at night. More recent data are inconsistent, so many protocols now prioritise taking it consistently, at the same time each day.

Body rhythm involved

Bone-marrow DNA synthesis may peak in the evening and night.

Other cancer therapy medicines

5-Fluorouracil (chronomodulated)

5-FU infusion

Overnight infusion, peak ~04:00

Cancer therapyEmerging evidence

Oxaliplatin (chronomodulated)

Eloxatin

Daytime infusion, peak ~16:00

Cancer therapyEmerging evidence

Immune checkpoint inhibitors

Pembrolizumab, nivolumab

Morning infusions

Cancer therapyEmerging evidence