Remember that song by Queens of the Stone Age? You know… the one that goes “nicotine, Valium, Vicodin, marijuana, ecstasy, and alcohol. c-c-c-c-c-cocaine.”
Man, that song takes me back. No, there was never a time when I was a totally drug addled mess, it just reminds me of when I first heard the album “Rated R” by them. Also, it gives me a lovely idea for a series of posts… Why? Because everybody likes learning about drugs! So, I’ll be detailing some of the unique chemistry/science behind the drugs, and perhaps any experiences I’m willing to share…
For starters, we have nicotine: a stimulant naturally produced in the nightshade family of plants! Right off the bat, we can see that there’s a single chiral center. This naturally occurring S-enantiomer is responsible for all of the physiological effects associated with nicotine. But, if for whatever you ingest a genetic oddball plant or a synthetic racemate, don’t worry, because the R-enantiomer is still biologically active, but only about half as potent.
If you’re getting your fix from nicotine, you’re most likely getting it by smoking tobacco, but there are a few alternatives: dip, snuff, snus, or chewing tobacco. All of which are inherently gross, albeit enjoyable, because ultimately, all of these routes of ingestion can lead to some form of cancer. It’s not the nicotine that’s the problem, but it’s the other carcinogens present in tobacco and tobacco smoke that’ll do you in. Considering that smoking is the most common method of nicotine ingestion, this is doubly upsetting due to the inefficient nicotine delivery method of smoking.
The flashpoint of nicotine is a low 95 C, and the point of autoignition is right around the point of vaporization1,2. So, if you smoke, you actually ingest much less nicotine than is present in the leaves. Therefore, you’re also ingesting more combusted plant material, naturally occurring carcinogens, etc, than optimal. I don’t mind that people smoke, but I’m dumbfounded that we haven’t developed a more efficient method of nicotine intake, that would still pair well with reading a newspaper, drinking coffee, or going out to a bar/party.
Once nicotine is ingested, it’s carried through the bloodstream to the brain, zips through the blood-brain barrier, and gets to work as an acetylcholine receptor agonist³, which boosts the levels of a few neurotransmitters, including dopamine, serotonin, and norepinephrine, resulting in that “nicotine buzz.” In addition, tobacco leaves contain a few natural monoamine oxidase inhibitors4 (MAOIs). MAOs do a whole bunch in your body, in particular, they can metabolize certain neurotransmitters such as (surprise, surprise…) dopamine, norepinephrine, and serotonin. In addition to helping you keep that nicotine buzz going a bit longer, whatever evolutionary advantage the nightshade family gained by producing nicotine or other metabolites, it also developed a method to increase certain metabolites’ effectiveness in mammals! Call it evolution, call it ‘design’, call it whatever, but it’s brilliant engineering of some kind, and I think that’s pretty fucking cool.
With regard to more recent developments in nicotine enjoyments, there’s menthol. It will give your cigarettes or dip a minty refreshingness, and will also prolong the time it takes for your body to metabolize nicotine to cotinine.5 Cool, right? (No pun intended…) However, the cooling sensation apparently makes it easier to smoke more with each drag, and ingest more nicotine, thus eventually making it harder to quit.6 I’m going to posit that the combination of more nicotine and a longer half-life isn’t exactly helping the addiction situation, either. Also, maybe some of you have heard that if you smoke menthol cigarettes, the menthol will “crystallize your lungs”? I’ve so far been unable to find any definite scientific data regarding it, but according to the most legit source I found, it’s all just a myth. And a hokey one at that…
Once you’ve had your way with nicotine, cytochrome p450 enzymes get to work metabolizing it into cotinine, and a bunch of other goodies:7
Next up on the hit-list (pun intended), Valium!
Because it’s not chemistry, supporting anecdotes info is included below, along with references.
Well, I was a smoker, originally picking up the habit in high school, and continuing halfway through college. I eventually realized I needed to quit sometime, for fear that if I didn’t set a hard deadline, I’d be sucked in forever. Quitting during school would have been a terrible, bitter, face-clawing experience, so I planned to quit after finals last year. After my last final in May, I smoked a well needed cigarette, threw away the rest of my pack, and went cold turkey. That being said, it’s just over 6 months later, I’m still smoke free, and now I have plenty of money for tasty beers. Definite improvement. So don’t smoke, kids.
 Sorry, but I’ll have to pass on describing any biochemical processes with anymore detail than wikipedia can offer. I wouldn’t consider myself qualified. And, to be honest, with respect to nicotine, I’m not all that interested the the biochemistry side of things. I just wanted to share the weird decomposition fact, the MAOI thing, and the menthol oddities. That being said, Future “Summer Series” posts will include more fun, gritty organic details (syntheses, anyone?) and reserve biochem data/info only if there’s something specifically neat about it, e.g., a synergizing metabolite somewhere down the metabolic pathway.
 Metabolism and Disposition Kinetics of Nicotine (Exceptionally detailed, and also gets credit for the equally exceptionally detailed reaction scheme)