Ok massive post here, sorry, this area really interests me.. apologies for tl;dr!
Going to side-step a lot of this debate - I would have a lot to say re taking drugs while fixing mental health but most points have been made and while I always want to get the HR info in, unsolicited advice tends to have the effect it has had in this thread.. just remember how easy it is to lose sight of what is the right thing for you MDB, when you are looking at yourself from your own perspective it's hard to see clearly. Doesn't mean outside perspectives are
always more accurate, but sometimes it's good to hear them even if you then think what a load of bollocks. Helps clarify things a little. If that makes sense? I've done so many silly, ill-advised, contrary and downright self-destructive things that have led me to a very dark place and I would not wish anyone else to follow, so am itching to give a load of unwanted advice, but I will refrain, promise. (Well maybe I already gave some but I didn't mean to, honest!!)
Anyway. Do read monsta's post. That whole thread from Fairnymph is pretty awesome. It's a little old so there may be new evidence, and quite a lot is based on anecdotal info, but it's by far the best resource of its type I've seen and I've been in awe of her ever since I read it. Bear in mind lack of info about harm does not mean there is no harm, don't take it as gospel as with anything on the internet, but it's definitely a really useful thread
This topic is relevant to my interests though and wanted to help so here's my added bits and bobs (bit geeky sorry, feel free to say if I am making no sense to you)
Re downers:
Mirtazepine has quite a complex action (to say the least). One of it's primary MOAs is as a sedating antihistamine, which is why it helps you sleep, and why it's not a good idea with downers. Whether it would actually potentiate respiratory depression or not (in the way that mixing alcohol, benzos and opioids can make you unexpectedly very dead, because they enhance the effects of one another) is kind of a moot point to me as sedation + downer can cause so many other dangerous problems - ranging from passing out in an awkward position and causing nerve damage (yes this is a thing) to choking on your vomit and dying a la Jimi and countless others. Proceed with extreme caution.
Re opioids specifically:
Mirtazepine may reduce the pleasurable effects from opioids due to a complicated and not fully understood (by me anyway :D) action on a specific serotonin receptor subtype. This is my personal speculation, but if it reduced pleasure from opioids without reducing respiratory depression (I don't know if this is the case or not but from what I have read it sounds like it) it could cause people to take dangerously high doses chasing the feeling, resulting in, well, death. Combined with the sedative properties, this worries me a lot. Again: please, proceed with extreme caution.
Re amphetamines and the like:
It seems that it can also reduce the high from dopaminergic drugs (stims, basically) via the same mechanism. There are studies I've read that to suggest it does reduce the pleasurable effects of amphetamine and methamphetamine, relating to this particular receptor action (inverse agonism of 5HT2c if anyone is interested ha) - will dig them out if you like (infact I'll try to do so anyway when I have time).
Re serotonergic drugs:
Mirtzepine does have serotonergic activity - it's not a reuptake inhibitor like SSRIs/SNRIs but it indirectly does act as a serotonin agonist as well as a noradrenaline agonist. It's quite selective and has a very complicated relationship with serotonin, so I am nervous about commenting here really.. It would seem logical that it would be okay in moderation, as it's the reuptake inhibitors such as SSRIs and tramadol, or excessive dosing of drugs that release serotonin such as MDMA and PMA, that worries me - but I really can't say about safety with MDMA, methylone etc. I'll try to do some more research if you like? You're right, it is less serotonergic than SSRIs, but that statement is somewhat simplified as there as loads of different receptor subtypes and complex interactions between neurotransmittors and nothing is ever simple when it comes to psychopharmacology, unfortunately.. In the spirit of HR I would have to say it would not be wise mixing mirtazepine with anything strongly serotonergic though, I'm sorry
Re hallucinogens:
I would be wary of taking hallucinogens with mirtazepine, as one of the main serotonin receptor subtypes it acts upon is also important in the action of a lot of hallucinogens - as Fairnymph's thread says, be careful, could be unpredictable/stronger than anticipated which with hallucinogens is not really what you are after. Could be very unpleasant.
In summary for tl;dr:
Downers in general - bad idea, could lead to death.
Opiates - very bad idea, reduce high, poss increasing risk of OD and therefore death.
Stims - could reduce effects. No idea about safety.
Serototonergics - very difficult to say, could be okay but wouldn't like to risk it myself. Mirtazepine is an indirect serotonin agonist and has a v complex action on serotonin receptors, and I've not seen any safety data or evidence so it's a gamble. HR says no.
Hallucinogens - could possibly cause strong/unpredictable trip so steer clear IMO.
I've not looked into the CYP-450 metabolic interactions because I don't know enough about all that really and it would take a lot of reading.. maybe sometime I will, when I have a lot of time on my hands
I could also go on for hours about why Drs prescribe SSRIs first line and why antideps often don't work on people, or work on one person but not another, but my fingers and head are tired :D Basically, there really haven't been any studies that manage prove that one antidepressant is superior to another. They are all broadly the same, with a few exceptions perhaps (although this is questionable). However, different people respond to different drugs; hence what works for your mate may not work for you, and vice versa. Also depends what you are looking for (added anxiolysis, added sedation, not to cause sexual dysfunction etc). As it takes 2-4 weeks to really see if an AD is going to work, then another 2-4 weeks on the next drug if the first one didn't help, all that trial and error can be horrid I know.. waiting and getting side effects and losing hope etc.. but it is worth it if you are clinically depressed and you find the drug that does work, as anyone who has been through this can testify, so if you and your doc think meds might help it is worth sticking it out if you can (IMO etc).
So, bearing all that in mind, essentially SSRIs are 1st line because a) they are as effective as other classes and work just as quickly according to current evidence; b) their side effect profile
tends to be more tolerable/safer although obviously this is subjective and occasionally people find they react v badly, same as most drugs; c) they tend to be safe in overdose unlike the TCAs such as amitriptyline, which can cause fatal heart arrhythmia - clearly this is v important for suicidal peeps; d) there's a lot of research pushed by big pharma into SSRIs therefore a big evidence base (not necessarily accurately reflecting things but that is another rant); and e) they're generally fairly cheap. And f) most GPs can't get you access to speedy, good, free/cheap therapy. Which is a crying shame, but again, another rant.
(Couldn't help myself it turned out haha, now I really am tired! Doubting my decision to return to BL now
)
Best of luck to you MDB - really hope the mirtazepine and counselling helps you, and any recreational activities (at all) that you participate in are helpful and not hindersome, and that you practice HR
Oh, just read your last post - shit mate, please don't take random pharms from India - I know I said no lecturing, but chlorpromazine - whoa - people can have agonising/dangerous reactions to that (acute dystonia/torticollis, especially common in young people; it causes Parkinsonian symptoms; can cause horrible restlessness, shaking, shuffling, etc etc.. moreso than many other antipsychotics). It's bad bad bad and it's not generally prescribed here anymore for good reason. Be really careful with ordering meds, I definitely wouldn't recommend taking an antipsychotic for sleep - the risk:benefit is not in your favour by any stretch. Sedating antihistamines are a much more sensible idea, just be careful with the ol' delirium if you munch too many (hydroxyzine's a good 'un IMO, promethazine is the best I find).
Hope that helped and wasn't immensely boring or patronising or anything, and good luck with your recovery
(Disclaimer - I've not added sources or references as I haven't got time; always question everything, don't believe a random girl on the internet, for all you know I'm a 13 yr old with google open etc etc..
and this is a very complicated area, I could have got things wrong for sure. I'll check my references though and hopefully then it will be a bit more trustworthy/accurate