Benzos half-life vs. duration of effect?

[bronson]

I was curious if anyone knows why half-life doesn't always correlate to duration of effect.

Take two drugs for example...

Diazepam - hL(20–100 hours)

&

Clonazepam - hL(18–50 hours)

Diazepam has the much higher half-life, however the effects of the Clonazepam can be felt much longer. Just strikes me as odd.

 

[Mr Blonde]

I am fairly sure it has to do with how well they bind to receptors and how readily they cross the blood-brain barrier.

 

[qwe]

i think it has to do with protein binding. the proteins in the blood offer a huge storage space for drugs, and different drugs with different fat/water solubilities and chem properties will have different protein binding affinity. the more it is stored inert in the blood, the longer it'll last because it won't go through metabolism and won't get you high till it gets back into solution

then again i guess half-life probably takes this into account by default?