From what I've read, Doxy is much preferred over Amoxicillin for treatment of Lyme.
Based on the properties of these antibiotics, this seems backward.
Doxy is bacteriostatic. The definition of a bacteriostatic antibiotic = an antibiotic that prevents the growth of new bacteria without outright killing existing bacteria.
Amoxicillin is bactericidal. The definition of a bacteridical antibiotic = an antibiotic that kills existing bacteria.
Wouldn't Doxy simply prevent your spirochete count from increasing, while Amoxicillin may actually reduce the spirochete count?
I'm sure there is a logical explanation for this. Does Doxy become bactericidal when given in doses that are larger than conventional?
Thanks for your thoughts.
William
Posts: 131 | From MD | Registered: Jul 2008
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adamm
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Doxy needs to be taken at a higher dose than that at which most physicians will prescribe it to be bacteriocidal. For adults, this dose is 400-600 mg/day.
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stymielymie
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ABX bacteria should be cultured to test whic h abx kills it. abx are to generally given prior to a culture. doxy has an afinity to kill bb so doxy is given. amox is given for everything even though a bacteria may be resistant to this abx.
it is important not to taken abx for too long a period without stopping, ie pulsing. this prevents the bacteria not not become resistant the abx.
there is a strain of staph called mrsa that is resistant to almost all bacteria. ift developed after 30 years of abx given for any little cold or sneeze.
this will be a major problem for the future of medicine.
yes higher doses work better of doxy but it is still bacteriastaic not cidal.
docdave
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massman
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Any "scientific evidence" that supports these theories that higher doses of doxy changes its function and that it is bactericidal with lyme ?
I feel this is a very important thread and it is not getting much action.
Would love to hear others experiences + info.
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posted
It may be due to the way that both drugs work, Amoxicillin is a cell wall antibiotic (weakens links in the cell wall), doxycycline is a protein synthesis inhibitor (keeps the ribosome from being used to produce proteins).
Both drugs have studies showing MIC and MBC values in vitro (in the lab) against Bb, but in live humans it is a try and see situation.
All antibiotics have different concentrations into some areas, some will have better intracellular levels than others, some will cross into the spinal fluid better or cross the blood-brain barrier.
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CD57
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I was told that higher doses of doxy are bactericidal.
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-------------------- You never know how strong you are until being strong is the only choice you have. Posts: 807 | From South Dakota | Registered: Jul 2005
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massman
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CD57 - did a doc tell you that ?
My sis has a masters in nursing, is studying for a doctorate + teaches as a prof in a state college. Sharper than most MDs, IMO.
I quizzed her quite a bit + she cant really figure why a bacteriostatic is used + how it can become a bacteriocidal at higher doses.
There seem to be many relapses after taking a break from doxy.
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stymielymie
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excellent article very long unable to cut and paste full explanation of abx in general
docdave
[ 28. December 2008, 09:55 AM: Message edited by: stymielymie ]
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david1097
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The way I learned it was that bacteriostatic stopped the progression of the infection and both allowed the immunue system to regain ground and allowed the bacteria to live it normal life span then die a natural death, without replication.
Ie. Neither will kill the bacteria instantly, it is just a question of the timing but in the end it is dead.
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david1097
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On the doxy vs amoxy, I think the preference is due to the effectiveness of doxy against some of the other common tick borne bacterial infections that might be missed. This is especially true in early stage.
At least thats what I remember from someplace.
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charlie
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I actually posed this question to a pharmacologist once...his response...only the macrolides, (zithro,biaxin,erythromycin,ketek,rulid) change from bacteriostatic to bactericidal with increased dose.
Tetracyclines are bacteriostatic period, according to him.
I think the magical transformation between classes is just a given we are supposed to accept. not me.
Charlie
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DebAz
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Charlie
If this is true of those abx.. how much of a dosage do you think it would take to change over??
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charlie
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Deb, IDK but zithro if taken daily builds up in the system (72 hr half life I think) and the 500 mg loading dose is thought to be bactericidal.
our usual dose of biaxin 500mg 2X/day is thought to be bacteriostatic.
somebody out there ought to be able to answer this...the retired pharmacologist I had access to is now in a nursing home or maybe in the CVS in the sky.....
Charlie
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DebAz
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Here is the link that was posted above as it did not work because of two things. So I am reposting and it is a good article.
posted
I was looking for some other drug information and came accross this about Doxy
"Doxycycline is capable of crossing into the brain, and a dose of 500mg per day of Doxycycline is considered enough to be bactericidal. Any lesser dose is considered bacteristatic (bacteristatic means it can stop the bacteria from spreading but is ineffective at eradicating the disease)."
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stymielymie
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important info: bugs are abx specific!!!!!!!!!!! this means that if you do a throat swab, they culture the swab, grow the bacteria ,then put disc of abx on the culture plate. where bugs are killed, that is the abx to use period. it has nothing to do with name, price, kind of abx. whatever kills the bugs on culture ,will kill the bugs in the body.
abx should not be just tried until one works, that is why we have drug resistant bacteria, and it is becomeing more of a problem every day.
PLEASE READ THE ARTICLE ABOVE IT IS AN EXCELLENT ARTICLE AND EXPLAINS EVERYTHING ABOUT ABX.
DOCDAVE
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