Why is time to steady state independent of dosing FREQ

[AxiomaticTruth]

P. 243 FA2015

I understand why time to steady state depends primarily on half-life and is independent of dose (ie time to steady state of 5mg/ml versus 10mg/ml is the same bc it's around 4-5 half-lives). But why also independent of dosing frequency? I figured if you dose like 2 times in a half second (impossibly ofc), then you'll definitely reach steady state quicker. In fact, isn't that what a loading dose basically is? Unless I'm misinterpreting heir wording of "dosing frequency," maybe they mean # of half lives?

---

Members don't see this ad.

 

[pacman2018]

Ultimately, you just need to remember the 4-5 half lives to reach steady state. Decreasing the dosing interval (i.e. going from q24h to q12h) will increase the steady state concentration, but not the time required to reach it.

If you look at this curve, increasing interval will shift the curve up because you are redosing at higher concentrations. Ultimately, it will still take the same amount of time for the steady state to be achieved. If you look at it like climbing stairs, you are climbing the stairs faster (dosing more frequently) but you have farther to go (higher steady state concentration) so you reach the top at the same amount of time as climbing slower and less stairs.

Using a loading dose will reduce time to reach steady state though because if the concentration starts higher, it makes sense it would take less time to reach steady state if you start closer to the goal concentration.

 

[AxiomaticTruth]

Ohhhh I see. So dosing amount and dosing frequency both increase the steady state, but the time is the same. I was looking at Kaplan pharm videos and they only mentioned the dosing amount. In my example scenario, if I did do 2 doses in a half second AND kept giving 2 doses every half second, the steady state would be astronomically high for obvious reasons, but STILL the time to reach steady state is the same. I see. Thank you.