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Thread: Metronidazole treatment question

  1. #1
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    Default Metronidazole treatment question

    Hello,

    1. Does anyone know if I need to turn off UV light as well as aquarium light when treating the tank with Metro?

    2. Also I have heard 1g/20gal once a day for 10 days or 1g/20gal every 8 hours for 5 days. Anyone have experience as which is more effective or does it make any difference?

    Thanks in advance.

  2. #2
    Registered Member seanyuki's Avatar
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    Default Re: Metronidazole treatment question

    Metronidazole is light sensitive,aquarium light off,UV light off,remove charcoal if any.
    500 mg per 10 gallons for 12 day and raise water temperature to 33 Celsius.
    Grasshopper
    Francis

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    Default Re: Metronidazole treatment question

    Thank you for the information...Is it once a day treatment for 12 days?

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    Registered Member seanyuki's Avatar
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    Default Re: Metronidazole treatment question

    Yes.

    Quote Originally Posted by RNJ View Post
    Thank you for the information...Is it once a day treatment for 12 days?
    Grasshopper
    Francis

  5. #5
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    Default Re: Metronidazole treatment question

    To avoid the propagation of misinformation metronidazole is not visible light sensitive. It's absorbance tails off before 380nm. Turning off the aquarium light can't hurt but unless you are working with some serious actinic metal halides it is very unlikely that your aquarium light will have any impact on metronidazole.

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    Registered Member seanyuki's Avatar
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    Default Re: Metronidazole treatment question

    Is Metronidazole light sensitive? To answer yr question post #29


    http://forum.simplydiscus.com/showth...ank-with-metro



    Quote Originally Posted by JamesW View Post
    To avoid the propagation of misinformation metronidazole is not visible light sensitive. It's absorbance tails off before 380nm. Turning off the aquarium light can't hurt but unless you are working with some serious actinic metal halides it is very unlikely that your aquarium light will have any impact on metronidazole.
    Grasshopper
    Francis

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    Registered Member bluelagoon's Avatar
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    Default Re: Metronidazole treatment question

    It is light sensitive. Keep powder in a light free container. Lights out in a tank when using it. AND if you take it stay out of the sun light as much as possible.

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    Default Re: Metronidazole treatment question

    Light inactivation of metronidazole sensitivity discs
    P. H. JONES AND ANNE P. SCOTT
    From the Public Health Laboratory, Lewsey Road, Luton, LU4 ODZ, UK

    One should take the extra 5 minutes to read the science before one offers an opinion that one makes sound definitive.
    This is a definitive article on light sensitivity. Though there was an effect with natural light on metronidazole, there was no effect with artificial light.

    Everyone seems to have their own opinion on how to treat with metro. There are scientific papers that show a three day course was sufficient to cure it in angelfish.

  9. #9
    Registered Member smsimcik's Avatar
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    Default Re: Metronidazole treatment question

    Quote Originally Posted by captainandy View Post
    Light inactivation of metronidazole sensitivity discs
    P. H. JONES AND ANNE P. SCOTT
    From the Public Health Laboratory, Lewsey Road, Luton, LU4 ODZ, UK

    One should take the extra 5 minutes to read the science before one offers an opinion that one makes sound definitive.
    This is a definitive article on light sensitivity. Though there was an effect with natural light on metronidazole, there was no effect with artificial light.

    Everyone seems to have their own opinion on how to treat with metro. There are scientific papers that show a three day course was sufficient to cure it in angelfish.
    The only thing definitive about that article is that they were testing metronidazole on sensitivity discs in a lab situation. Metronidazole was inactivated by sunlight and was not inactivated by the artificial lights in their lab.
    Does this work the same for metronidazole in solution in an aquarium? Who knows? It's never been tested that way. How many types of artificial lights did they test? What color spectrum? What strength? How long were they exposed?

    Manufacturers of metronidazole sell it in light proof containers for a reason. It's even written on the label of metronidazole injectable solution after you open the bag to protect it from light. It doesn't specify whether it's sunlight or artificial light.
    No one is here trying to propagate misinformation. The fact is metronidazole is light sensitive under the right conditions.
    So what's the harm in turning off the lights when treating with it in a home aquarium to insure it maintains full strength? The fish don't care if the lights are on or not.
    Last edited by smsimcik; 12-03-2020 at 01:53 PM.

  10. #10
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    Default Re: Metronidazole treatment question

    OK. I want to make it very clear that I am not attacking anyone on this thread, just the facts.


    I have a PhD in organic chemistry, I've published articles in PNAS, JACS, ACIE and J. Med. Chem. as well as multiple patents. Three drugs I helped design are currently undergoing clinical trials. My current job is to design manufacturing processes for active pharmaceutical ingredients. I have personally done the experiment with much more sensitive molecules where aqueous solutions of a compound are stable indefinitely under indoor lighting but are 100% decomposed by mere seconds of exposure to daylight. My undergraduate research was focused on monitoring UV degradation of polypropylene. I can assure you that I am speaking with some authority on the subject.

    Like Steve said, the paper you reference says that artificial light had no impact on metronidazole activity.

    The UV/Vis spectrum of metronidazole is published: Special Topics and Reviews in Porous Media 5(4):361-367 and others.

    In aqueous pH 6.8 phosphate buffer absorbance beyond 380 nm is noise (i.e. not absorbing). Published spectra of common LED and fluorescent grow lamps for aquarium use have no emission above 380 nm. For the same reason we can't see UV light, metronidazole can't be decomposed by visible light. For the same reason we don't get a sunburn from indoor lighting, metronidazole can't be decomposed by typical indoor lighting.

    Manufacturers of metronidazole sell it in light proof containers to protect it from daylight.

    Does turning off the aquarium light when treating with metronidazole hurt? No. Could leaving your aquarium light on during metronidazole treatment lead to failure? Also no. Should you try and block sunlight that hits your aquarium during metronidazole treatment? Probably Yes. Should you turn off the UV light? Also yes.

  11. #11
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    Default Re: Metronidazole treatment question

    If I still haven't convinced you please google 'Metronidazole environment persistence'
    You will see many articles discussing the persistence of metronidazole in ground water, surface water, soil, drinking water, animal tissue etc.

  12. #12
    Registered Member smsimcik's Avatar
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    Default Re: Metronidazole treatment question

    Don't worry James, you've convinced me. I have only been sharing the information I was taught many years ago in veterinary school by my pharmacology professors. It has been a long held belief in the veterinary community that metronidazole is sensitive to all light and should be protected from light when being used. I and every veterinary clinician I know have always worked under the assumption that metronidazole has to be protected from light, particularly when in solution.

    You should send your findings to Pfizer. They still state on their insert for Flagyl (metronidazole) injectable solution that it is only stable for 72 hrs. after being exposed to room light. It also states that it should be protected from light when being stored. Since they don't distinguish between daylight and artificial light, one would have to assume they mean any light.

  13. #13
    Registered Member seanyuki's Avatar
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    Default Re: Metronidazole treatment question

    Hope you can provide the actual link to the scientific papers the cure in three days in angelfish using metronidazole .Could benefit us discus hobbyists.

    Quote Originally Posted by captainandy View Post
    Light inactivation of metronidazole sensitivity discs
    P. H. JONES AND ANNE P. SCOTT
    From the Public Health Laboratory, Lewsey Road, Luton, LU4 ODZ, UK

    One should take the extra 5 minutes to read the science before one offers an opinion that one makes sound definitive.
    This is a definitive article on light sensitivity. Though there was an effect with natural light on metronidazole, there was no effect with artificial light.

    Everyone seems to have their own opinion on how to treat with metro. There are scientific papers that show a three day course was sufficient to cure it in angelfish.
    Grasshopper
    Francis

  14. #14
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    Default Re: Metronidazole treatment question

    As a member of the pharmaceutical industry, stating it is only stable for 72 hrs probably means they only have stability data on it for 72 hrs multiplied by a fudge factor.

    We had a compound stable for 2 years with a specification of 99.0% purity. After 2.5 years the purity tested at 98.9%, it failed specification and was therefore no longer suitable. We set the use-by/retest date at 6 months.

  15. #15
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    Default Re: Metronidazole treatment question

    Thanks for the clarification, it is fascinating how a precaution to avoid UV exposure morphs to no exposure to any artificial light, that recommendation is (via google) almost universally associated with recommendations for metro usage. So now the next question is what is the actual half life of metro in solution in the tank. The recommendation here is 500 mg/10 gal/day x 12 days, but I have seen recommendations for up to every eight hour dosage with a duration of 7 or 10 days or here 12, and also usually a recommendation of up to 50% WC with each new dose. Depending on the half life of the medication, dosage frequency as well as the frequency and volume of water changes, this could lead to a much higher concentration of metro by day 12. Really need a PDR for fish

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