Thread: What is phenylephrine?

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    What is phenylephrine? 
    Pfizer to Sell New Sudafed Formula to Curb Illegal Use, AP Says
    2004-12-23 08:10 (New York)

    By Amy Hellickson
    Dec. 23 (Bloomberg) -- Pfizer Inc. plans to offer a new
    form of its Sudafed over-the-counter cold medicine that
    doesn't include an ingredient used to make methamphetamine,
    the Associated Press reported, citing a company spokeswoman.
    The new drug, called Sudafed PE, will be available in
    the U.S. on Jan. 10, AP said, citing spokeswoman Erica
    Johnson. The company will replace the substance
    pseudoephedrine with phenylephrine, AP said.
    Methamphetamine is an illegal stimulant that users
    snort, smoke or inject, AP said. Law enforcement officials
    shut down 7,000 meth labs last year, AP said, citing the
    Drug Enforcement Agency.

    (AP 12-23)

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    Bluelight Crew Dave's Avatar
    Join Date
    Dec 1999
    It's a close analog of pseudoephedrine, with a few small differences:

    - Has a phenyl -OH group which is meta to the "tail" (if the carbon on the aromatic ring which is attached to the "tail" is numbered 1, the carbon to which the -OH is attached is numbered 3)
    - Has different stereochemistry about the chiral centre
    - Is missing the secondary methyl group in between the -OH and the amine

    These differences would make it very difficult to make methamphetamine from phenylephrine (in a clandestine setting).

    Check out Chemfinder to see the structures and a bunch of links to information on these compounds. I think the first three searches are free, then you have to do a free registration to perform more searches.

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    I imagine it has a similar mode of action like pseudoephedrine?

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    I saw something about this (last night I think) scrolling across the bottom of the screen on the Fox News channel. But they also said, which I don't think anyone here mentioned yet, is that they will continue to sell the original Sudafed formula. I don't know if they will sell both for awhile and then phase out the original Sudafed, but they didn't say that...all they said was that both will be available.

    As for C10H12N20, you asked whether phenylephrine has a similar mode of action to pseudoephedrine. I'd have to assume so otherwise it really wouldn't make a good replacement for it. What I wonder is, do amphetamines have decongestant properties? I believe that's what the pseudoephedrine is in there for. Anyone know about that, either through literature or personal experience?

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    Bluelight Crew Skyline_GTR's Avatar
    Join Date
    Aug 2002
    In the UK they already sell both types of Sudafed - the pseudo products tend to be behind the counter, and the phenylephrine on the shelves on the shop floor.

    I understand that phenylephrine has a shorter half life and isn't as effective as a decongestant as pseudoephedrine.

    This is the abstract to a paper:

    Pharmacokinetics of oral decongestants.

    Kanfer I, Dowse R, Vuma V.

    School of Pharmaceutical Sciences, Rhodes University, Grahamstown, South Africa.

    Only three drugs are commonly used as oral decongestants--phenylpropanolamine (PPA), pseudoephedrine (PDE), and phenylephrine (PE). They are all chiral drugs that exist as stereoisomers. It is possible that each enantiomer can reflect significant enantioselective differences with regard to both pharmacokinetic and pharmacodynamic effects. Both PPA and PDE are readily and completely absorbed, whereas PE, with a bioavailability of only approximately 38%, is subject to gut wall metabolism and is thought to be absorbed erratically. Peak concentrations are reached between 0.5 and 2 hours after administration.

    All three drugs are extensively distributed into extravascular sites (apparent volume of distribution between 2.6 and 5.0 L/kg). No protein-binding data in humans are available. Whereas PPA and PDE are not substantially metabolized, PE undergoes extensive biotransformation in the gut wall and the liver. Elimination of PPA and PDE is predominantly renal, with urinary excretion being pH dependent. Half-lives are relatively short, approximately 2.5 hours for PE, 4 hours for PPA, and 6 hours for PDE. Elimination of PPA and PDE may be rapid in children, and the agents should be used with caution in patients with renal impairment. In addition, PPA increases caffeine plasma levels and decreases theophylline clearance. Reduced metabolism of PE occurs with concurrent administration of monoamine oxidase inhibitors. No direct relationship between nasal decongestant effect and plasma concentration has been established.

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    Bluelight Crew fastandbulbous's Avatar
    Join Date
    Jul 2004
    that rainy little island off europe
    These differences would make it very difficult to make methamphetamine from phenylephrine (in a clandestine setting).

    I'd say pretty much impossible, as phenylephrine doesn't have an alpha-methyl carbon group (it's optically active about the carbon containing the benzylic OH group), and it's an endlessly complicated route to add an alpha methyl group to the phenethyl skeleton.

    Phenylephrines structure is actually similar to that of adrenaline, except in phenylephrine, the para-OH group is replaced by a hydrogen. It's the 'active' ingredient in lem-sips (I put active in commas, as IMO, it's a shite decongestant, unless you apply it directly to the mucous membrane)

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    Well... levamfetamine is used as a decongestant in Vicks Nasal Decongenstant sticks. Any drug that works on adrenogenic system pretty much is a good candidate for being nasal decongestant. Hell, even MDMA is a nasal decongestant to a certain degree...

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