>SSRIs, for example, take weeks to have an effect.

I am not sure that the time it takes to have an effect is a good metric for whether or not something has potential for abuse. Sure SSRIs take a few weeks to have a noticeably effect but they also takes weeks to tail off. The area under the curve is not necessarily different.

Yeah but you can't pop a Prozac if you're feeling sad and expect to feel better within a reasonable time frame. There's also no high, you just start feeling normal again if you're depressed and it's the right drug.

https://www.quora.com/Why-are-SSRIs-typically-prescribed-bef...

"This last item makes SSRI's abuse-safe: contrary to benzodiazepines or opiate-based painkillers, there's no risk of abusing them for pleasure, as they're, once again not "happy pills" and there's no high. They even worsen symptoms for most people at first. That has to do with their mechanism and is their major flaw but serendipitously it strongly protects against recreational use."

Actually, time-to-action is exactly what separates addictive drugs from non-addictive alternatives. The brain cannot abstract pleasure from what are extremely subtle mechanisms.

I'd say length-of-action is just as big a factor, especially with prescription pain-killers. When people take drugs with short half life's, they tend to 'dose up'. Which, if you're not careful can easily lead to addiction.

Also, I do believe personality comes into play. When I was taking the max dose of Tramadol for over a year, I stopped dead three weeks post-op. The only noticeable side-effect was a runny-nose for a few days, hardly a big deal.

I just mean in terms of potential addictiveness. Mind you, weakly binding drugs will usually be coupled with higher doses. So there's not exactly a separation between time-to-action and length-of-action and binding affinity. Dont worry about coatings and whatnot. If someone wants to abuse a drug, it will most likely be crushed up. Now, if we are talking about the actual substance - depending on whether it is a direct agonist versus a prodrug that goes through multiple passes, or has other rate limiting behavior. -- This will definitely affect the addictiveness of the drug. But 100% in addition to the binding affinity and the receptors affected. So I agree, it's a combination of a bunch of factors. But the ultimate end result, which is perceived duration, perceived impulse, is responsible for a large part of the addictive threshold of that drug. The drug's makeup is clearly responsible for everything, I'm not saying perception trumps the actual chemistry. I just mean, if there is very little perceived impulse, there will most likely be little to no physical dependency. Again, this is based on the tendency of someone to use a drug at what we want to call effective doses, or in abusing it, supra-effective doses.

the speed at which they take effect is actually one of the most important things about addiction, that they make you feel better instantly. future positive outcomes are traded for instant rewards and negative future outcomes.