I've been taking 40 mg oxycodone daily for about 3.5 weeks now and 30 mg mirtazapine daily. I was expecting I wouldn't be able to go to work while in withdrawal so I took the time off. I would say the W/D was cut in intensity by about 60% because of the mirtazapine. I only felt slight depression and the anxiety wasn't incapacitating like it normally is. Physically I felt pretty shitty but it wasn't anywhere near as bad as normal. I felt like I could have gone to work.
I would've thought mirtazapine would make the withdrawal worse. It's an alpha-2 adregenic receptor antagonist which is the opposite of clonidine which is use for W/D. High norepinephrine is also a key player in opiate W/D. Mirtazapine acts as NE reuptake inhibitor increasing it's levels which I thought would make the anxiety and physical W/D worse. It's also a kappa agonist which antagonizes Mu opoid receptor effects.
I felt less high when I took opiates on mirtazapine so maybe the kappa agonism plays a role in reducing dependence levels. I was also thinking the NE reuptake might desensitize NE receptors making W/D less severe. This is just speculation though. I was if anybody had something else to add. Either their experience with opiate withdrawal on mirtazapine or some reason why it can help with W/D.