My Hydroxyurea came with paperwork to take it with a full glass of water with or without food, My hematologist suggested half hour before or after eating.
I take it in the morning but it is your choice. If you go on Chemocare.com you can print or view a lot of information on Hydroxyurea.

The information sheet said to aim for minimum 64 ounces of fluid daily to flush the toxic effect.

Eileen