While yes Amitriptyline (elavil) is a sedative (a very good one at that) it's sedative qualities wear off after two nights of taking it.. I say that as in taking it purely to help you sleep just at night. I'm perscribed it at 50mg and take it only rarely if i absolutely cannot sleep, it knocks me out in an hour, if taken a second night it takes 100mg to put me out, a third well hell I would never do that. It's safety profile is one of the worst of any medication out there (as in effective dose is close to the toxic dose). Now for dexedrine involved (also which i take daily, my vice) I can say there is a horrid reaction if the two are mixed, even if taking Amitriptyline to sleep off the crash of amphetamines, the feeling one would get if you mix amphetamines with a higher dose of dipenhydramine (since Amitriptyline works on those muscinrinc receptors)
But this only applies to taking it at first when those effects are pronounced when one first begins taking it. However your taking it daily and due to the variability of Amitriptyline it's hard to say how it would effect your dexedrine. If its working well for you as an anti-depressant, and the negative side effects aren't there I could see it possibly increasing the effects since you're depression would be lessened thus making the positivity which amphetamines produce be more apparent than usual since your well-being is already boosted. But for anyone who might be reading this take this warning. Don't ever mix the two off the bat thinking that it would help boost your speed high. That would be one shitty feeling popping an elavil and then some speed that would be a nasty feeling, the amphetamines keeping you awake while the other working to put you asleep (again i'm speaking about someone naive to Amitriptyline). Personally I would never touch Amitriptyline while having amphetamines still active in your system, same would also go for any kindof stimulants). But reflekt if Amitriptyline is working for you i wouldn't worry about mixing them, just make sure you're taking them daily because stopping Amitriptyline for even a few days will bring back the sedative effects, and to sum up no it's not going to have a biological effect which will increase dexedrines effects through the CYP-metabolism like say mixing grapefruit juice with diazepam.
I hope that helped somewhat, as I was writing that my train of thought grew disjointed i'll check back in later if you have any more questions about it specifically with both of their metabolisms, or if i was too unclear.
