It was my impression that the 48h regimen with different antiemetics might be superior, because several people chose that way. But as jgm63 wrote, it's bound to be fine and Stan's guide agrees. Bottom line seems to be go with what you feel most comfortable, and at least two members kept it down without any help at all. So, you're not missing anything, I am. Really just confused now why there is a 48h regimen...
I think a key reason the 48 hour regime exists is because it has a lower EPS risk, since you're not taking so much antiemetic at once.....
See discussion below.
----------------------------------------------------------------
48 hour vs stat antiemetic regime
----------------------------------------------------------------
This discussion includes discussion of EPS, however we should note that most people don't get EPS. Some people might get some degree of EPS. In some rare cases, however, EPS can be quite severe, and could interfere with or even prevent an attempt. (To try to gauge the frequency, the article "Metoclopramide-Induced Acute Dystonic Reaction: A Case Report" states : "Acute dystonic reactions, the most common type of extrapyramidal symptom associated with metoclopramide, occur in approximately 0.2% of patients (1 in 500) treated with 30 to 40 mg of metoclopramide per day.")
The 48 hour regime might have a lower EPS risk since you're not taking so much antiemetic at once.
However, some people don't like the "drawn out" nature of the 48 hour regimen, and prefer the stat dose.
Some people suggest there's a lower vomiting risk with the 48 hour regime, but I haven't seen evidence to convincingly support that (a handful of anecdotal cases is not enough to make real conclusions, and people discussing those cases may not have measured the large number of successful stat dose cases, etc).
There could be additional benefits to the 48 hour regime, other than the lower EPS risk, however it is not clear what those are (if any), although speculations have been made. If you have strong factual information on this then please share.
It's generally considered a good idea to do some "tests" of taking the antiemetic (eg try 5mg of metoclopramide, then try 10mg a day or two later).
Ideally you would build up to testing the actual anti-emetic regimen you plan to use.
This may help ensure you find the best regimen for you, however some people may find this excessive and choose to do some basic tests without testing the full regimen.
If the initial tests with 5 or 10 mg of metoclopramide causes some degree of EPS, then those people might choose to go with the stat dose, so they don't have to have 48 hours of those symptoms. Taking diphenhydramine (50mg) after taking the stat dose may help.
If the initial tests with 5 or 10 mg of metoclopramide causes some degree of EPS, then another option might be to use the 48 hour regime but take 15mg of diphenhydramine with each antiemetic dose over the 48 hour period, to offset any EPS. Note : I can't say if this is a good option since I'm not medically qualified.
As mentioned, doing a full test run of the actual anti-emetic regimen you plan to use would help to feel confident in your regimen.
If the initial tests with 5 or 10 mg of metoclopramide do not cause any EPS, then this suggests a 48 hour regimen would likely be viable (assuming you are okay with the longer regimen), and the full test run might not be needed. However you may still wish to do the full test run, or a partial test run, eg for 24 hours.
If the initial tests with 5 or 10 mg of metoclopramide do not cause any EPS, but you are intending to use a stat regime, then a full test run is still advisable to see if the stat dose causes any EPS (and if so, what severity).
If you intend to use the stat regimen, but did a full test run and found the EPS were significant and not satisfactorily mitigated by taking diphenhydramine, then you could switch to the 48 hour regimen, and try testing that. If you started with the intention of using the 48 hour regimen but when testing found it to be uncomfortable (eg due to minor EPS over an extended period), then you might switch to the stat regimen combined with 50mg diphenhydramine, and try testing that.
Some people may consider the "full test run" to be over-the-top, or not want to take unnecessary additional meds.
Some people may do little or no pre-testing, and simply go with the stat dose, taking the view that if they get EPS symptoms they won't last long before the final dose it taken. However, if the EPS were severe, it could interfere with or prevent an attempt (although this should be rare). Ultimately, you have to weigh the risks and decide. It is also possible to use the 48 hour regime without any pre-testing, since the regime does not use high doses, and you could always stop or adjust if you experience issues during the regime. However if you have a limited time window for your attempt, then you might want to pre-test to try to ensure everything will go smoothly during the planned window.
Having diphenhydramine on standby may help you to feel more confident. If you need to feel more certain you could do the full test run, or at least do some testing, as explained above. It would seem wise to at least do the initial tests with 5 or 10 mg of metoclopramide.
In all cases, it's probably a good idea to have diphenhydramine on standby just in case you get some EPS.
( n.b. I'll add the above discussion as an additional post on my "N guide" thread )