The half life of a drug is 10 hours and is taken every 12 hours. How long will it take to reach peak loading equilibrium?

I started taking a drug called Tikosyn (Dofetilide) while in the hospital (February 10th though 13th 2020). It’s half life is 10 hours and I take it every 12 hours. Each dose is the same (500 mcg).

My nurse could not or would not answer this question and my doctor never talked to me before I was discharged. I searched the internet for an answer to no avail. So I did a crude calculation (see below).

Looks like equilibrium will be reached on or about day 5. I should be at the equilibrium stage by now where the drug titer will not continue to increase.

What do you think?

Day 1…....Peak Titer
500—————-500
500—————-750
Day 2
500—————-875
500—————-937.5
Day 3
500—————-968.75
500—————-984.38
Day 4
500—————-992.2
500—————-996.1
Day 5
500—————-998
500—————-999
Day 6
500—————-999.5
500—————-999.8
Day 7
500—————-999.9
500—————-999.9