Do lower affinity drugs take a longer time for pathways to rebound?

Affinity has to with strength of activating a receptor others options.

Do those with stronger affinities result in more likelihood to rebound?


1 Answer 1


This article is a good starting point for this question.

It states: "The binding affinity, defined as the strength of these interactions, is translated into physico-chemical terms in the dissociation constant (Kd), the latter being an experimental measure that determines whether an interaction will be formed in solution or not."

The dissociation constant is explained fairly well by Wikipedia. So, the higher the affinity of a drug with it's target, the stronger it binds.

I'm assuming that by "rebound" you mean that the pathway will regain its ability to function normally.

When someone takes a quantity of a drug, it disperses throughout the body. At any given time, at any given point in the body there is some concentration of the drug. If the affinity of the drug to it's target is very high, lots of molecules will bind to the target, whereas with a low affinity drug, fewer molecules will bind.

As time goes on, the body will filter out some of the molecules, and the remaining drug molecules will diffuse to fill the space where the filtered molecules were located. As this process continues, the concentration of the drug will decrease, lowering the dissociation constant of the drug-target equation, which means that fewer of the molecules will bind, and some of the bound molecules will be released to maintain equilibrium. The longer this process continues, the closer to "normal" the pathway will become, until the concentration of the drug is negligible.

Keep in mind that all of this is dependent on the rate at which the body eliminates the drug (and how quickly the drug degrades on it's own). See here for equations and such. While concentration of the drug is a large factor in it's effects, the half-life of the drug may be a better indicator of how long it takes for a pathway to rebound than affinity of the drug. For that matter, affinity is probably a factor in the length of a drug's half-life.

  • $\begingroup$ Another way of stating what my question is asking is withdrawal time for these drugs although I am more interested in simply the rebound of the pathways and not the actual withdrawal effects. There is no doubt this occurs considering if you stop taking benzos you can experience insomnia on and off for weeks and months. You answer didn't really answer this question. $\endgroup$
    – William
    Commented Jun 5, 2018 at 15:23
  • $\begingroup$ In that case could you try to phrase your question differently; it doesn't seem to ask the question effectively. Go in to more detail about what you're looking for. Even your above comment isn't particularly helpful; are you asking if withdrawal time of a drug is dependent on affinity? Additionally, please define "rebound". $\endgroup$
    – Astrolamb
    Commented Jun 5, 2018 at 15:37
  • $\begingroup$ Another user gave me the rebound pathway term so it seems to me there is discrepancy on what people agree on. Yes I am essentially trying to determine withdrawal time based on affinity although withdrawal effects can be caused from a host of issues and not simply how long for a brain receptors to start functioning how they were prior to taking the drug. $\endgroup$
    – William
    Commented Jun 5, 2018 at 16:01
  • $\begingroup$ Ok, that clears up a lot. Now are you asking how to predict withdrawal time mathematically based on affinity, or if there is a relationship between the two at all? $\endgroup$
    – Astrolamb
    Commented Jun 5, 2018 at 16:22
  • $\begingroup$ yes. I have read time taken might effect it also assuming there might be some universal formula or something. $\endgroup$
    – William
    Commented Jun 5, 2018 at 16:28

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