A friend of mine sent me this today. He works for PFizer Canada. Scientist of sorts. Very smart man.
I hope this helps anyone who needs it. Good Luck.
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*Information requested by Health Canada for Market Authorisation of Electronic Cigarettes and e-liquid products in Canada.
Pharmacokinetics of Propylene Glycol and Glycerin USP
Propylene Glycol is metabolized in the human body into pyruvic acid (a normal part of the
glucose-metabolism process, readily converted to energy), acetic acid (handled by ethanol-metabolism),
lactic acid (a normal acid generally abundant during digestion), and propionaldehyde. Inhalation of
the propylene glycol vapors appears to present no significant hazard. Propylene glycol does not cause sensitization and it shows no evidence of being a carcinogen or of being genotoxic.
*Some electronic cigarette users who inhale propylene glycol vapor may experience dryness of the throat. As an alternative, some suppliers will put Vegetable Glycerin in the "e-liquid" for those who are allergic (or have bad reactions) to propylene glycol.
Glycerol/Glycerin is used for an evaporative fogging agent as an alternative to Propylene Glycol in some solutions for "electronic cigarette" use, mostly for those with a physiological sensitivity or other health concerns.
Glycerol/Glycerin is also produced as a byproduct of refining of cooking and salad oils, and various brands (e.g, NOW) are sold to the retail market as "Pure Vegetable Source" glycerin, 100% pure, which is safe for ingestion/inhalation.
Pharmacokinetics of Nicotine
Effects of nicotine.[11]
As nicotine enters the body, it is distributed quickly through the bloodstream and crosses the blood-brain barrier reaching the brain within 10-20 seconds after inhalation.[12] The elimination half life of nicotine in the body is around two hours.[13]
The amount of nicotine absorbed by the body from smoking depends on many factors, including the types of tobacco, whether the smoke is inhaled, and whether a filter is used. For chewing tobacco, dipping tobacco, snus and snuff, which are held in the mouth between the lip and gum, or taken in the nose, the amount released into the body tends to be much greater than smoked tobacco. Nicotine is metabolized in the liver by cytochrome P450 enzymes (mostly CYP2A6, and also by CYP2B6). A major metabolite is cotinine.
Other primary metabolites include nicotine N'-oxide, nornicotine, nicotine isomethonium ion, 2-hydroxynicotine and nicotine glucuronide.[14] Under some conditions, other substances may be formed such as mysomine.[15]
Glucuronidation and oxidative metabolism of nicotine to cotinine are both inhibited by menthol, an additive to mentholated cigarettes, thus increasing the half-life of nicotine in vivo.
I hope this helps anyone who needs it. Good Luck.
_________________________________________________________________________________
*Information requested by Health Canada for Market Authorisation of Electronic Cigarettes and e-liquid products in Canada.
Pharmacokinetics of Propylene Glycol and Glycerin USP
Propylene Glycol is metabolized in the human body into pyruvic acid (a normal part of the
glucose-metabolism process, readily converted to energy), acetic acid (handled by ethanol-metabolism),
lactic acid (a normal acid generally abundant during digestion), and propionaldehyde. Inhalation of
the propylene glycol vapors appears to present no significant hazard. Propylene glycol does not cause sensitization and it shows no evidence of being a carcinogen or of being genotoxic.
*Some electronic cigarette users who inhale propylene glycol vapor may experience dryness of the throat. As an alternative, some suppliers will put Vegetable Glycerin in the "e-liquid" for those who are allergic (or have bad reactions) to propylene glycol.
Glycerol/Glycerin is used for an evaporative fogging agent as an alternative to Propylene Glycol in some solutions for "electronic cigarette" use, mostly for those with a physiological sensitivity or other health concerns.
Glycerol/Glycerin is also produced as a byproduct of refining of cooking and salad oils, and various brands (e.g, NOW) are sold to the retail market as "Pure Vegetable Source" glycerin, 100% pure, which is safe for ingestion/inhalation.
Pharmacokinetics of Nicotine
Effects of nicotine.[11]
As nicotine enters the body, it is distributed quickly through the bloodstream and crosses the blood-brain barrier reaching the brain within 10-20 seconds after inhalation.[12] The elimination half life of nicotine in the body is around two hours.[13]
The amount of nicotine absorbed by the body from smoking depends on many factors, including the types of tobacco, whether the smoke is inhaled, and whether a filter is used. For chewing tobacco, dipping tobacco, snus and snuff, which are held in the mouth between the lip and gum, or taken in the nose, the amount released into the body tends to be much greater than smoked tobacco. Nicotine is metabolized in the liver by cytochrome P450 enzymes (mostly CYP2A6, and also by CYP2B6). A major metabolite is cotinine.
Other primary metabolites include nicotine N'-oxide, nornicotine, nicotine isomethonium ion, 2-hydroxynicotine and nicotine glucuronide.[14] Under some conditions, other substances may be formed such as mysomine.[15]
Glucuronidation and oxidative metabolism of nicotine to cotinine are both inhibited by menthol, an additive to mentholated cigarettes, thus increasing the half-life of nicotine in vivo.
I just wanted to let you know, When I started Vaping, I was using 100% PG. There's nothing wrong with PG, other than the fact that there is less vapor and I got cottonmouth, dry throat. Sort of reminded me of my teenage years If you know what I mean 
