You should in theory be fine if you already have a sub in your system then take it again since whateevr heroin you do is going to be pretty much blocked depending on how much you took of Sub its like if you were taking sub for a few months daily then did heroin one day about 8 hours or so after taking sub you may feel a slight high that diminishes quickly but you wouldnt have to worry about going into precipitated withdrawal the next dose you take. May I ask if your terrified of the precipitated withdrawals then why purposely do it to yourself?
And 30 hours?! How do you take your suboxone do you also inject that? Does your heroin really last you 24+ hours ? If so that's a very slow metabolism heroin has a very short half life. I've heard of it a few times though where people don't get physically sick until 30 hours and still go into withdrawal at 24+ hours from taking sub but most of the time if taken sublingually in a low dose people don't have to wait that long unless they have a slow metabolism of course. When sub is injected the chances of going into precipitated withdrawals go way up same with snorting it which usually means the person has to wait longer to induct onto suboxone than they would've if they took it sublingually the theory is the naloxone makes the precipitated withdrawals even worse than it would have been with just buprenorphine withdrawals since not as much naloxone gets absorbed via the sublingual route along with the fact the bupe creeps up on you instead of hitting you all at once like happens with IV bupe. That seems weird to me 30 hours mabye cause I get away with it at only 4 hours every time with no trouble but I hear of this happening a lot more to people that inject suboxone.
Morphine's half life is indeed short(1.5-4h, mean 2-3) but this is a perfect example of half-life being irrelevant to duration of action.
Due to it's very poor lipid solubility, morphine takes a long time to fully penetrate the CNS. This is why it still takes 20-30 minutes to feel the full effects of morphine, even when injected intravenously.
The trade-off is that one it does enter the CNS, it takes just as long for it to exit. Thus, each morphine molecule hits multiple receptors, each time it enters the brain. This gives moderate-large doses an extended duration.
A perfect example is to compare it to oxycodone. Oxycodone's half-life is actually longer than morphine's, but it is well known that IV morphine has a longer duration/ "holds" longer.
At very high doses, however, this effect becomes exaggerated, and a sufficient dose of IV morphine/diamorphine can last upwards of 12 hours.
With diamorphine, a massive amount of morphine iimmediately ends up in the brain, and with good dope, I have been high 16 hours later.
I understand the OP's plight, as I too have to wait 30 hours, after doing massive shots of dope that is.
(Edit: Ok wow, after reading the entire thread, that is just crazy. PW's to avoid PW's???)
Well at least now everyone knows why heroin can last so fucking long. People put way to much stock in half-life...