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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 13 of 13. This is the beginning of the thread.
Posted by ed_uk on December 31, 2004, at 18:50:53
Has anyone else noticed that methylphenidate (Ritalin) is available in most countries whereas the 'true' amphetamines such as Dexedrine and Adderall can only be prescribed in a few countries?
It's almost as if some countries haven't noticed the major similarities between Ritalin and the amphetamines and so Dexedrine and Adderall are prohibited whereas Ritalin is used.
As far as I know, methamphetamine (Desoxyn) is only available on prescription in Chile and the USA!
Ed.
Posted by lars1 on December 31, 2004, at 23:02:33
In reply to True Amphetamines Prohibited!, posted by ed_uk on December 31, 2004, at 18:50:53
Hi Ed,
It's true that methylphenidate and amphetamines have a lot of similarities. However, high-dose amphetamines have been fairly conclusively shown to cause dopaminergic neurotoxicity, while the few studies on high-dose methylphenidate haven't found any. This is probably related to their different modes of action: methylphenidate works as a dopamine uptake inhibitor, while amphetamines act not only as uptake inhibitors, but also as dopamine-releasing agents. I don't know whether this is actually the reason methylphenidate is more widely available. It could be just because illicit use of amphetamines is widespread, but you never hear of underground Ritalin-trafficking rings.
Best regards,
Lars
Posted by blanding on January 1, 2005, at 1:30:05
In reply to Re: True Amphetamines Prohibited!, posted by lars1 on December 31, 2004, at 23:02:33
Doctors and government officials don’t like to talk much about it, but there is an obvious reason people get hooked on methamphetamine: sex.
Meth eventually destroys the sex drive, but for a short while it can boost sexual appetite and performance more powerfully than drugs such as cocaine, doctors say.
“Who wouldn’t want to use it? You lose weight and you have great sex,” Assistant U.S. Attorney Paul Laymon said sarcastically at the meeting of the Tennessee task force.
FULL ARTICLE:
http://www.msnbc.msn.com/id/6646180/Seems that methylphenidate doesn't increase sex drive compared to meth.
And now you know . . . the rest of the story.
Posted by Dan Perkins on January 1, 2005, at 12:33:24
In reply to True Amphetamines Prohibited!, posted by ed_uk on December 31, 2004, at 18:50:53
I've taken both ritalin and dexedrine and was never able to distinguish much of a difference between the two. I have always just considered them both on a sort of amphetamine continuum with coffee on one end and cocaine or meth on the other end. Ritalin and dexedrine, from my first-hand experience, would fall closer to the cocaine end of the spectrum.
The US government, btw, still gives dexedrine to fighter pilots to stay alert and focused for their missions. They gave it to all soldiers in Vietnam, as I learned when I showed a dexedrine pill to my high school english teacherwho was also a Vietnam vet. He said "hey I remember that . . ." .
Posted by ed_uk on January 1, 2005, at 17:03:33
In reply to Re: True Amphetamines Prohibited!, posted by Dan Perkins on January 1, 2005, at 12:33:24
Hi everyone!
Thanks for your responses :-)
Don't forget that Ritalin does have a high abuse potential.... all those people grinding up their pills and snorting them to get a cocaine-like high! I imagine that quite a few people sell their prescriptions.
Although high doses of amphetamines may be neurotoxic, I'm not sure whether this is a problem with much smaller therapeutic doses.
Regards,
Ed.
Posted by lars1 on January 2, 2005, at 1:36:19
In reply to Re: True Amphetamines Prohibited!, posted by ed_uk on January 1, 2005, at 17:03:33
> Hi everyone!
>
> Thanks for your responses :-)
>
> Don't forget that Ritalin does have a high abuse potential.... all those people grinding up their pills and snorting them to get a cocaine-like high!I've read about this happening. Apparently snorting it puts it into the bloodstream very rapidly and produces a "rush" that is quite different from what happens when you take it orally. From what I gather, it's not particularly addictive so long as you take it as directed (i.e., in the prescribed dose, by the prescribed route). Kids with ADD don't seem all that enthusiastic about taking it.
> I imagine that quite a few people sell their prescriptions.
>I am of two minds about this. On the one hand, it shows that an illicit demand does exist. On the other hand, it shows that people who regularly use the drug are still quite willing to part with it, which is hardly consistent with a dangerously addictive drug. It's hard to imagine the same thing happening if, say, a heroin addict somehow got hold of a prescription for heroin.
> Although high doses of amphetamines may be neurotoxic, I'm not sure whether this is a problem with much smaller therapeutic doses.
>
> Regards,
> Ed.I'm not sure either. Unfortunately, most of the research in this area seems to be sponsored by NIDA (the National Institute on Drug Abuse, an agency of the US Government) as part of the "war on drugs," with the goal of "proving" that drugs are dangerous, not showing how much of them you can safely take. Therefore, there are many studies showing that high doses of amphetamines are damaging, but very few that would shed light on the threshold dose for this damage to occur. One interesting study in rats(1) found that doses of about 16mg/kg/day of either amphetamine (AMPH) or methamphetamine (METH), administered via continuous infusion over a period of 3 days, caused significant dopaminergic damage, while METH administered at the same rate for 1.5 days did not. Neither did METH administered at 8mg/kg/day for 6 days. (The experimenters also tried the latter two schedules for AMPH, but for some reason did not report their results.) These doses are expressed as mg of the base, not of the salt the way Adderall and Dexedrine are dispensed. To convert, you would need to multiply by about 1.6. Also, keep in mind that rats metabolize AMPH about 10 times faster than humans, so the drug concentration in their blood will reach only a tenth of what it would be for the same (mg/kg) dose in humans. After applying both of these correction factors, the study would seem to suggest that for a 60kg (132 lb) human, 80mg/day of Dexedrine or Adderall would be safe, while 160mg/day would not. According to the Adderall prescribing info, the maximum recommended dose is 30mg/day, so it appears that if you stay under that, you will be safe. However, human-animal equivalents are only approximations, and the margin of safety is not as big as you might like. Also, humans tend to take amphetamines in discrete doses, not by continuous infusion like the rats did, and it's not clear if that would make a difference. Finally, in the rat study, the high dose of amphetamine had to be administered for 3 days before damage occurred. It's possible that damage would eventually occur at lower doses, and the study just didn't run long enough for that to happen.
One other thing that concerns me is that in humans, some of the beneficial effects of amphetamines (increased energy and motivation) seem to decline over time. Potentially, this could be a reflection of neurological damage, i.e., the drugs are burning out the same neural systems that they are stimulating. However, this tolerance could equally well be just a result of a (reversible) down-regulation of dopamine receptors.
The above may sound rather negative about amphetamines, but the general medical consensus still seems to be that amphetamines are safe when used in the recommended doses. Many people with ADD take them for years without noticeable problems. And FWIW, I do take them myself. I would be interested in any comments anyone else might have about amphetamine safety.
With best regards,
Lars(1) Brain Res. 1984 Jun 15;303(2):359-64.
Further evidence that amphetamines produce long-lasting dopamine neurochemical deficits by destroying dopamine nerve fibers.Ricaurte GA, Seiden LS, Schuster CR.
Methamphetamine and amphetamine were continuously administered to rats for 3 days by means of subcutaneously implanted osmotic minipumps. The total daily dose of each drug was approximately 4 mg/day. Dopamine, norepinephrine and serotonin determinations two weeks later indicated that both amphetamines produced a selective striatal dopamine depletion. Anatomical studies indicated that this depletion was associated with striatal nerve fiber degeneration. To determine whether this fiber degeneration induced by amphetamines was dopaminergic, the long-lasting dopamine depletion produced by methamphetamine was antagonized with alpha-methyl-para-tyrosine. This prevented the appearance of nerve fiber degeneration after methamphetamine. These findings suggest that amphetamines produce a long-term striatal dopamine depletion by destroying striatal dopamine nerve fibers.
[Some of the interesting results of this study are only mentioned in the full article. I have an electronic copy which I'd be happy to send to anybody who'd care to babblemail me. BTW, this study has the same lead author as a notorious study on MDMA (Ecstasy) neurotoxicity from 2002, which eventually had to be retracted. -L]
Posted by ed_uk on January 2, 2005, at 11:32:54
In reply to Re: True Amphetamines Prohibited!, posted by lars1 on January 2, 2005, at 1:36:19
Hi Lar!
Thanks for posting the studies :-)
>Apparently snorting it puts it into the bloodstream very rapidly and produces a "rush" that is quite different from what happens when you take it orally.
Yes, it's said to be quite similar to cocaine... but with a longer duration of action.
>Kids with ADD don't seem all that enthusiastic about taking it.
Well, I think it would be fair to say that many children suffer quite a lot of side effects from Ritalin.
>On the other hand, it shows that people who regularly use the drug are still quite willing to part with it, which is hardly consistent with a dangerously addictive drug.
I'd guess that some people obtain prescriptions that they have no intention of using themselves. Some people probably try Ritalin once or twice and don't like it.... but then they continue to have it prescribed so that they can make a lot of money from selling it.
>the study would seem to suggest that for a 60kg (132 lb) human, 80mg/day of Dexedrine or Adderall would be safe, while 160mg/day would not.
It's really impossible to extrapolate animal studies to humans. Their physiology and anatomy is not the same as ours. Now what we really need is studies on humans! Any volunteers??????!!!!!!!
>One other thing that concerns me is that in humans, some of the beneficial effects of amphetamines (increased energy and motivation) seem to decline over time. Potentially, this could be a reflection of neurological damage, i.e., the drugs are burning out the same neural systems that they are stimulating. However, this tolerance could equally well be just a result of a (reversible) down-regulation of dopamine receptors.
Yes, I've also had these thoughts. No one will prescribe me a stimulant though (live in UK) so I suppose I don't need to worry.
>And FWIW, I do take them myself.
Which drug do you take? What dose? What do you take the stimulant for?
All the best,
Ed.
Posted by blanding on January 2, 2005, at 18:26:45
In reply to Re: True Amphetamines Prohibited!, posted by lars1 on January 2, 2005, at 1:36:19
Quote: "These findings suggest that amphetamines produce a long-term striatal dopamine depletion by destroying striatal dopamine nerve fibers."
If so, mustn't this process eventually result in Parkinsonian syndrome, akinesia etc.?
Any empirical evidence out there?
Posted by lars1 on January 3, 2005, at 1:58:25
In reply to Re: True Amphetamines Prohibited! » lars1, posted by ed_uk on January 2, 2005, at 11:32:54
>
> It's really impossible to extrapolate animal studies to humans. Their physiology and anatomy is not the same as ours.Agreed.
> Now what we really need is studies on humans! Any volunteers??????!!!!!!!
That would be difficult, since most of the studies seem to end with the subjects' brains being sliced up. But with newer imaging techniques, it's not out of the question.
>
> Which drug do you take? What dose? What do you take the stimulant for?
Adderall, 10-20mg/day, for better focus, less apathy, and as an antidepressant-augmentor. It's too early at this point to say if it's actually going to work out for me. I'd like to give methylphenidate a try, partly because of safety concerns, and am working on getting the pdoc to go along. (He says that adults tend to do better on Adderall.)Lars
Posted by lars1 on January 3, 2005, at 2:41:00
In reply to Re: True Amphetamines Prohibited!, posted by blanding on January 2, 2005, at 18:26:45
> Quote: "These findings suggest that amphetamines produce a long-term striatal dopamine depletion by destroying striatal dopamine nerve fibers."
>
> If so, mustn't this process eventually result in Parkinsonian syndrome, akinesia etc.?
> Any empirical evidence out there?I'm no expert in this. However, my understanding is that amphetamines damage or destroy dopamine nerve terminals, but they don't actually kill the neurons (nerve cells) themselves. The neurons are still alive, they just don't work very well. In parkinsonism, on the other hand, neurons actually die off.
I'm not aware of any documentation showing that long-term medical users of amphetamines have an increased rate of parkinsonism. Neuropsychiatric studies of long-term illicit meth abusers have found some abnormalities, but not parkinsonism as far as I know.
-L
Posted by ed_uk on January 3, 2005, at 17:17:25
In reply to Re: Amphetamine Safety » ed_uk, posted by lars1 on January 3, 2005, at 1:58:25
>> Now what we really need is studies on humans! Any volunteers??????!!!!!!!
>That would be difficult, since most of the studies seem to end with the subjects' brains being sliced up. But with newer imaging techniques, it's not out of the question.
Hi!
Studies using imaging techniques sounds like a good idea. Did you see my post (to you) about distigmine (Ubretid)?
Ed.
Posted by lars1 on January 5, 2005, at 2:28:33
In reply to Re: Amphetamine Safety » lars1, posted by ed_uk on January 3, 2005, at 17:17:25
> Did you see my post (to you) about distigmine (Ubretid)?
Yes. But it doesn't seem to be available where I live (in the U.S.).
-L
Posted by lars1 on January 13, 2005, at 4:20:33
In reply to Re: True Amphetamines Prohibited!, posted by blanding on January 2, 2005, at 18:26:45
> Quote: "These findings suggest that amphetamines produce a long-term striatal dopamine depletion by destroying striatal dopamine nerve fibers."
>
> If so, mustn't this process eventually result in Parkinsonian syndrome, akinesia etc.?
> Any empirical evidence out there?Here's an abstract that might explain why parkinsonism doesn't tend to happen:
This is the end of the thread.
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