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JAYARAMAN KIRUTHI VASAN
JAYARAMAN KIRUTHI VASAN
6/20/2013 3:10:20 AM
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Master
Re: Patch type medicine
amrutah,

Transient electronics is soon to gain market acceptance in the coming decade. Tasks/treatment which would be otherwise unimaginable could be possibly done with such implantable/decomposable electronics. The intricate details of their impact on the immune system needs to be studied for seamless implementation.

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Gregst
Gregst
6/19/2013 9:56:23 PM
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Newbie
Re: Very, very old idea
@eafpres: Indeed, I'm aware of the fact that the transdermal diffusion if very slow. Yet take a look at the chemical formula of nicotine that is frequently delivered by topical means: two well stabilized rings - hexagonal and pentagonal, the single polar group theoretically able to form hydrogen bond is N-H, and even it is not very active because it is stabilized by resonance within the ring. Nicotine pKAs are 6 and 11, pH of blood is 7.4, so the pentagonal N would become cationic, but it would be stabilized by resonance on the ring. Nicotine could be ionic only in salts, upon the salt dissociation it is a resonant structure, well stabilized. So, the molecula is essentially non-polar, will be subjected to the hydrophobic force, and will go through the phospholipid bilayer easily. Yet since dissociated nicotine is not ionic or polar under any physiological pH, it is not a subject to electrophoresis. The bottom line is that only small ions, such as moleculae of water or sodium would be able to get into the system circulation as a result of electrophoresis. Even potassium would have hard time penetrating it (potassium gets in through an active transporter). Hence, here is the question: what use does electrophoresis have for the larger ionic moleculae that need to get into the systemic circulation ? Apparently, none.

Another problem is that constant electrophoresis will remove the very same cations that by some chance got into the blood. In the very same way they got into the blood, they would be extracted from it by the negative electrode.

Yet another problem with both electrophoresis and diffusion is: we want the drugs in the systemic circulation, not in the local tissues. Imagine a significant release of certain bioactive moleculae into the local tissues: you might get necrosis there, cells would die, burst, release enzymes harmful to other cells...you know the rest. And you would get a huge concentration of these ionic bioactive substances in the local tissues prior to any of them would reach the blood vessels.

There is a good reason for why electrophoresis is not used in any known to me systemic drug delivery in the Western World.

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eafpres1
eafpres1
6/19/2013 8:44:11 PM
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Re: Very, very old idea
@Gregst--I think you missed the point. Diffusion through liquids is very slow--D < 10^-5 cm^2/s. iontophoresis uses the applied field to speed transport thus allowing controlled time vs dosage. Yes, some meds work well in simple transdermal application--pain meds, nicotine replacement, etc. But in cases where you need non-constant delivery this technology will be very useful. Also my understanding is people can tolerate and even benefit from current flow. So I would withhold judgement until we see applications. The enablement by the analog integration will lead to more ideas.

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Brad Albing
Brad Albing
6/19/2013 12:20:48 PM
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Re: No, Brad, you don't want to do that
Point taken. Now give me back my ions. In return, I'll resist the urge to post another corny engineering joke.

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Gregst
Gregst
6/19/2013 12:16:05 PM
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Newbie
No, Brad, you don't want to do that
You don't want to remove ions from your body unjudiciously, even the excessive ones. Removal of ions is a very precise function of your kidneys, and electrophoresis would not help. The other waste in your body is detoxed by the liver. If you lose your liver and kidneys, you are as good as dead, even with dialysis. No electrophoresis would help.

Actually, you might do some experiments. Do such electrophoresis that would remove from your body those pesky cations of sodium and potassium. I'd love to see you after that, not because I'm sadistic, but for scientific purposes only.

See, I have a unique point of view: I'm simultaneously an Electrical Engineer and Biochemist/Molecular Biologist. Sometimes, the purely engineering approach to biology looks very funny.

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Brad Albing
Brad Albing
6/19/2013 12:01:49 PM
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Re: Very, very old idea
@Gregst - Thanks - it's good to get info from someone who knows more about the biochemical and physiological aspects of this as opposed to just the electronics.

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Gregst
Gregst
6/19/2013 11:47:23 AM
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Newbie
Very, very old idea
     This is an ancient idea of delivery of medications by electrophoresis. It originated in the beginning of 20-th century, was very popular in Germany in 1920-s - 1930-s. It migh be good for some medications, not good for others. Ions would not simply penetrate the blood vessels and create a sufficient concentration in the bloodstream. Nay, the process is much more complicated. The other idea, currently widely used, is topical application of a medication, where the medication is propagated by diffusion. Why use electrophoresis if any medication, even non-polar, hydrophobic, can simply propagate by diffusion ?

    Large ions do not penetrate the biological cells easily. A cell is surrounded with the membrane, phospholipid bilayer, that is inside very ionophobic. Generally, to get ions through the membrane, we need to surround them with hydrophobic capsules, micelles, or somehow get them through the ionophores and active transporters in the membrane. Some ions can act outside the cells by binding to the receptors and being signalling molecules. On those occasions, electrophoresis might work.I'm saying might, because even if an ion gets into a blood vessel, what prevents it from getting outside of it and travelling to the electrode of the opposite polarity ? Does it mean that electrophoresis should be pulsed, in sync with the blood flow speed ?

  The idea of electrophoresis for a broader spectrum of medications is very naive. Most of those German inventions in physiotherapy gradually disappeared from the Western medicine. Some of them were very barbaric by modern standards, like treating the throat infections with UV light and heating the deep tissues with microwaves: imagine what genetic mutations both methods caused. But, of course, they were developed long before people knew about  DNA and mutations. Electrophoresis belongs to the same generation. I'm amazed that it is now revived as some form of panacea.

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Brad Albing
Brad Albing
6/19/2013 11:10:42 AM
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Re: Star Trek stuff
>>First thing that came to mind was the device that Dr McCoy used in one of the Star Trek movies. "I'm a doctor, not an analog design engineer."

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Brad Albing
Brad Albing
6/19/2013 11:08:32 AM
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Re: Patch type medicine
It would be interesting to see if the reverse method could remove enough waste products to make it useful.

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amrutah
amrutah
6/19/2013 12:41:32 AM
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Master
Re: Patch type medicine
Vasan,

     I agree, this is a very interesting post as well as the topic.  Also the reference you mentioned are useful.

    There is a lot of work going on where scientists are mimicking organs of chip. Brain-on-chip and lung-on-a-chip which are used for testing of drugs.  Many things are happening and soon there will catalogue of Transient Electronic products in market.

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