cytomel has a half life of 10 hours, meaning if you take 75mcg at 12pm, at 10pm, you will have 37.5mcg in your system, then in another 10 hours, you will have 18.75mcg, so you can take it all at once and it will stay in your system for over 24 hours but if you want to keep levels stable, splitting the doses would be optimal. i would take it twice a day, 37.5mcg every 12 hours.