Looking back through hard data on vapers' (personal) plasma nic tests, I can't find one that goes over 20ng. Values of 15ng - 18ng are achieved by using 36mg refills in high-power hardware such as APVs. Historically, such plasma nic levels in smokers would have been regarded as low. Today they are apparently about average for smokers as we read of smoker tests reading at 12 - 25ng, in contrast with double that in the past. Would you agree? (I haven't seen any *recent* smoking measurements over 30ng although *historic* ones are up to double this.)
A plasma nic level of 18ng in a vaper is at the
very highest end of the scale, according to reports here on ECF from vapers' tests with their local clinic. It would be far more common to see 8ng. A vaper at 18ng got there using 36mg refills in a high-power device or by vaping a lower strength for an extended period.
Nevertheless this does not indicate any less of an effect than a smoker achieves with a 25 or 30ng level: because (a) vapers' plasma nic levels are always considerably lower for the same effect, and (b) we know that the individual's tolerance to nicotine varies by a factor of 10, therefore a single individual's result is meaningless - we need measurements from several individuals using exactly the same gear before any attempt at the meaning of the result can be made.
We sometimes hear that average strength refills such as 18mg can produce a 'good result' in a short time (i.e. a few minutes, as with say a couple of cigarettes) - but where is the evidence for this? Where are the records of elevated plasma nic levels with a refill strength this low? No doubt 5ng or perhaps 10ng can be achieved, and perhaps more easily if the individual has a low tolerance to nicotine. Short-term readings of 15ng or higher seem to be exclusively with 36mg strength refills. However I welcome any new evidence that low-strength refills can produce rapid elevated plasma nic levels in vapers.
The benchmark ecig now is a mid-size unit (aka an eGo) with a clearo (that is to say, any kind of clear tank arrangement, of which there are hundreds). If you work with ten experienced vapers using this hardware and an 18mg refill (which is generally termed average although I'd call it average-low, since it is less than half the strength of a realistic-strength refill), then you might get results ranging from 3 or 4ng to 10 or perhaps even 12ng plasma nic measurement in the short term (say under 30 minutes), and perhaps an average around 6 or 8ng. No doubt it can be elevated to 18ng or so with time.
If you want to see a cigarette-like result then you need to use 36mg or 45mg refills as that is what they are for: a few puffs and the job is done. However, I feel there is some confusion here: an EV (electronic vapouriser) or ecig isn't a cigarette and doesn't act like one in any measurable way. We already know that vapers get exactly the same satisfaction from a slightly slower and very much lower plasma nic elevation in the EV compared to a cigarette. Apparently, there are few who actually want a very fast and hard hit (i.e. rapid plasma nic elevation and to a comparably high level) as a cigarette, otherwise people would be queuing up for 36 and 45mg refills - and they're not. We can measure the delivered nicotine level and it is always much lower than for smoking, *but it gets the same result*.
Another thing: if you take a smoker and measure their plasma nic level at say 20 or 25ng; then next day (from a near baseline level) have them vape hard with a 36 or 45mg refill and get up to the same level, then they will be experiencing significant symptoms of nicotine OD. The two things are not the same.
No amount of assuming that nicotine delivered by a cigarette and an EV are identical will make it so. The pure nic delivered by an EV is far more powerful - a plasma nic level of about 40% less does exactly the same job.
Of course, this is all anecdotal as it depends on the veracity of the reports here. Until this kind of research is carried out, anecdotal is all we've got. Some of the measurements we need are:
- Compare plasma nic results obtained with 18mg refills to 45mg refills. How many puffs and how long to max level. (Intellicig have done this but didn't publish the full results.)
- Compare plasma levels using 18ng, using subjects who have low and high tolerance to nicotine. This will tell you how this factor affects the plasma nic level. Caution: some subjects cannot tolerate over 6mg refills when using efficient gear.
- Measure the peak plasma level after ad lib vaping with their personal choice of hardware and refills, for subjects who have extremely low tolerance to nicotine (those who vape 6mg and cannot tolerate 12mg). This will tell us the peak satisfaction level for someone with very low tolerance to nicotine (it varies tenfold).
- Measure the peak plasma level after ad lib vaping with their personal choice of hardware and refills, for subjects who have extremely high tolerance to nicotine (those who vape 60mg and above, in order to avoid relapse to smoking, and who show absolutely no signs of over-consumption).
- Find a testing method that can actually measure nicotine plasma levels at the brain, 8 seconds after inhalation, and measure the elevation vs time. Statements that, when vaping, it takes 1 minute for any plasma nic elevation to show are simply ridiculous - the problem is the testing method. You can very easily test it yourself and dispel this myth: take a high-power device, fill it with a 45mg refill, have someone (not yourself) warm up the atomiser (the test is worthless with a cold atomiser), start your stopwatch - and take a big, 6-second hit. Pull it all into your mouth, hold it there for 2 seconds, pull it into the lungs, hold it there 2 seconds, then exhale it slowly through the nose.
I can guarantee what the result will be and it won't take a minute. Assuming you are a nic-naive user, best to have some heart rate slowdown medication handy for use in about 10 seconds
PG lock-in: I have read in a tobacco cigarette research paper that the more PG is included in a cigarette, the less nicotine is bioavailable. This is consistent with our experience although perhaps the time delay is the more noticeable effect. You could test this, no doubt, by measuring plasma nic levels with (a) nicotine mixed with water, spilled onto the arm; and (b) nicotine mixed with PG, spilled onto the arm. Our experience indicates that PG exhibits a lock-in effect. Starting with a low nic strength of course, in case you have a sensitive tester. Some people are virtually immune to it though, ask e-liquid manufacturing staff in corner-cutting enterprises where they don't glove up properly. Some get spills on themselves that stay there for hours, with no effect.