People can build up tolerance to an otherwise fatal poison by taking it in small amounts - apparently doing this is called Mithridatism (and yes, I had to cut and paste it from elsewhere).
What are the actual physiological functions that happen to build up that tolerance? I would have thought the immune system only protects against bacteria, but does it play a role?
There is no one mechanism. And this method is ineffective for many, if not most, toxic substances. Don’t count on it.
For poisons such as venom, subfatal doses stimulate the body to produce antibodies to the particular venom molecule. Hence they can inactivate it when they see it.
For opiates, and other similar drugs, what one sees is tolerance. Regular use results in a downregulation of the opiate receptors on the neurons, hence it takes a much higher dose to activate the same number of receptors in a tolerant opiate user than it does for a smaller dose in a new opiate user.
For alcohol, the liver’s microsomal enzyme oxidation system (cytochrome P450) gets stimulated after repeat exposures, and chews up alcohol a little faster. Barbiturates are handled similarly.
For arsenic, it’s really a pseudotolerance, not a true tolerance. As arsenic poisons the bowels, less of it is absorbed in the bowel in subsequent doses.
Other mechanisms are also in play for the above and other substances, weaving a myriad web of detoxification, altered absorption, and target organ resistance.
“…I spent the last 5 years building up a tolerance to iocaine powder!”
Sorry, had to be done.
Ah, crazyjoe, beat me to it!
[QUOTE=crazyjoe]
"…I spent the last 5 years building up a tolerance to iocaine powder!"QUOTE]
More likely a real good tolerance to baby laxative.
Amusing story about how that got to be called “Mithridatism”- a king of Pontus named Mithradites was so afraid of being poisoned he systematically took small doses of poison to build up immunities. Which was all well and good, until the Romans defeated him in battle and he tried to take poison to kill himself afterwards. Naturally, it didn’t work, so he was forced to fall on his sword.
As to actually answering your question… What Qadgop said.
Thanks, Qadgop. Oh, and cool story, appleciders… I guess there is such a thing as too much preparation.
Qadgop is, of course, correct. An interesting (to me, anyway) sidenote is that the antibodies against venom can be produced in non-human mammals and then used in humans. Much of the antivenin used for snake bites is created by giving doses of venom to horses, then isolating the antibodies to make the serum. This doesn’t have a salubrious effect on the horses, but it does save lots of human lives. I believe that the antibodies used to make many antibacterial vaccines is also produced in animals.
Haha. I just opened this thread to make sure that somebody made the obligatory reference to iocaine powder.
It’s said that if you build up this pseudotolerance by daily doses, it’s fatal if you stop abruptly and completely. Is that true, and if so, why does that occur?
Who says that about pseudotolerance? Pseudotolerance is the need to increase dosage that is not due to tolerance, but due to other factors such as: disease progression, new disease, increased physical activity, lack of compliance, change in medication formulation, drug interaction, addiction, and deviant behavior (I see a lot of this last one). Whether abrupt discontinuation of the drug is dangerous or not depends on what the drug is, what the underlying pathology is, and what the other factors are.
Certainly, rebound effects occur after withdrawal from some drugs, especially nitroglycerine, beta-blockers,
If one is physically addicted to barbiturates or alcohol, sudden withdrawal can be fatal.
Another great (OK – it’s the only other one I can think of) literary plot point revolving around immunity to poison is in Gary Jenning’s Raptor. (It’s been YEARS since I read it, so if I screw this up and someone can correct me, please do.)
The main character has built up an immunity to some poisonous substance and then uses his immunity as a means of murder. His bodily fluids are so toxic that he will kill anyone he has sex with.
But, happy ending! He finds a female who has built up the same immunity for the same purpose, so they can fuck each other silly for the rest of their days with no ill effects. Ain’t love grand?
There’s a scene in Colleen McCollough’s The Grass Crown that tells of King Mithradates returning to the court of Pontus after having been mysteriously absent for a couple of years. His sister/queen Laodice, has, in the meantime, taken a lover and is intent on killing her newly-returned husband. Of course, murder – particularly that of the king and/or his heirs – seems to be the national pasttime of Pontus, so the queen’s regi/fraterni/mariticidal intentions are boringly predictable.
At the banquet celebrating the king’s return, Laodice sidles up to Mithradates and seductively offers him a drink of wine from her own cup. Without hesitation, he takes the cup and downs a healthy swallow. Smacking his lips, he announces to the entire court exactly what poison she has used, and then procedes to explain exactly why it will not work on him. He then has his guards hold Laodice down and pours the remainder of the cup’s contents down her throat. As she begins to writhe and convulse, Mithradates lectures all those present on the standard effects of that particular poison, pointing out each of the symptoms as they occur.
Now THAT’S a lecture you’re not likely to forget.
As long as the question has been answered, I have an embarrassing story to tell about snakebite antivenin. When I was travelling to Sumatra in Indonesia, I was told that unlike the US, where there are only a few species of venomous snakes, and in the event of a snakebite they just treat you for all of them if they can’t identify the snake, Indonesia has so many venomous snakes that it is necessary to bring the snake with you to the hospital for identification.
I made the mistake of telling this story to a physician back in Jakarta. He was horrified. He said he wished people would stop repeating that stupid story, that people were coming into the emergency room after being bitten multiple times in an unecessary effort to catch a snake, or worse, with a not quite dead snake in a paper bag. I felt like a country bumpkin who bought the Brooklyn Bridge. What a maroon.