FightForIt
New Member
- Reaction score
- 0
I've read posts a few times that people think because minoxidil has a 22 hour half life in the scalp that only dosing once per day should be almost as effective as the recommended twice per day (Not always on this forum.) Now I'm not sure if minoxidil even has a 22 hour half life (some say it does, some say it's closer to 8 hours) but I've seen the 22 hour number a lot. I want to say that just because the half life of minoxidil is on the order of a day, doesn't necessarily mean it will be as effective by using it only once a day compared to the twice per day.
To illustrate this, I made a quick half life model of minoxidil in the scalp assuming that about 50mg gets absorbed at the time of dosing, and it's half life is 22 hours. I know that it takes about 4 hours for the minoxidil to be absorbed but that doesn't effect the illustrative purposes of this model. 50mg was chosen because 1mL at 5% should be close to 50mg of actual minoxidil on the scalp. The top chart is the start of the regime, and the bottom is once it has reached (psuedo)steady state.
Once steady state is achieved the average value for 1mL once per day in the scalp is about 67.5mg, and for twice a day in the scalp is about 134.5mg. Keep in mind this is only a simple mathematical model, and does not incorporate how minoxidil is absorped or metabolized other than a simple half life model, it just shows that just because something's half life is 22hours, doesn't mean it's as effective once per day as twice per day.
To illustrate this, I made a quick half life model of minoxidil in the scalp assuming that about 50mg gets absorbed at the time of dosing, and it's half life is 22 hours. I know that it takes about 4 hours for the minoxidil to be absorbed but that doesn't effect the illustrative purposes of this model. 50mg was chosen because 1mL at 5% should be close to 50mg of actual minoxidil on the scalp. The top chart is the start of the regime, and the bottom is once it has reached (psuedo)steady state.
Once steady state is achieved the average value for 1mL once per day in the scalp is about 67.5mg, and for twice a day in the scalp is about 134.5mg. Keep in mind this is only a simple mathematical model, and does not incorporate how minoxidil is absorped or metabolized other than a simple half life model, it just shows that just because something's half life is 22hours, doesn't mean it's as effective once per day as twice per day.
