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About Dr Alan Galbraith
Expertise
I can answer most questions on drugs, both medical and "recreational". Answers can be given in either technical or layperson terminology. My main areas of interest are psychiatric, gastrointestinal and cardiovascular drugs.

Experience
I have been a university lecturer/head of department for almost thirty years, but am now retired. My research interests were alcohol, smoking and cardiovascular disease. I am already a well established and highly rated expert in the pharmacy section of this site.

Publications
Principal author of "Fundamentals of Pharmacology" Editions 1-4 published between 1994 and 2004 by Pearson Education, Australia. Author of the 5th edition published 2007. Author of many scientific papers.

Education/Credentials
BSc(Hons);MSc;PhD;HECert

Awards and Honors
The 4th edition of my textbook was awarded the the Educational Book of the Year Award in Australia.

Past/Present Clients
See my profile in the pharmacy section.

You are here: Experts > Health/Fitness > Pharmacology > Pharmacology > Metronidazole and Vancomycin for CDiff

Pharmacology - Metronidazole and Vancomycin for CDiff

Expert: Dr Alan Galbraith - 10/31/2009

Question
QUESTION: Hi Dr Galbraith
I would be most grateful for your views on the following questions.

Upon a +ve diagnosis for C-difficile:

What is the concensus on the dosage and duration of course of treatment with Metronidazole for the first occurance of Cdiff diarrhoea?

Upon a relapse, if pt was prescribed a course of 9 days treatment:consisting of 6 days of Vancomycin alongside metronidazole for the full 9 days ( ie given both drugs for 6 days and only metronidazole for a further 3 days) ..

...BUT there was a period of over 40 hours ( 4 doses missed) starting on day 3 of the course where the metronidazole was not administered and two doses of the Vancomycin were not administered- would these ommisions affect the effectiveness of the treatment with these anitbiotics?

I hope that this makes sense!

Your opinion would be most greatly valued.

ANSWER: Dear Jill

Metronidazole (250mg qid) is usually used for at least 10 days when about 75% of patients respond. If there is no response after this time it probably will not work. Vancomycin (125mg qid)is better at producing a response (90+%)and this occurs usually after about 6 days although the drug is normally maintained for a further 4 days. Because of its cheapness and fairly good response rate metronidazole is still considered first line therapy. Furthermore, we do not want resistance to vancomycin to increase because of unnecessary use. Concurrent treatment is not normally recommended at this time.

I really do not know what the effects of the omitted doses would be but theoretically it could cause an increased likelihood of resistance developing but if this did not happen eradication of the bacteria should still be achieved.

Hope, like you, this makes sense.

Regards

Alan Galbraith

---------- FOLLOW-UP ----------

QUESTION: That's most helpful and a very quick response, thank you.

The reason behind the question about the missed doses is that there was then a further relapse of Cdiff diarrhoea after this concurrent treatment. ie , this concurrent course of treatment didnt work.

And as we're always all told to take antibiotics for the full course and at the times stated by the Dr,that by not being given those 4 doses would have possibly lead to the fact that the Cdiff came back again. ie not enough of the drug was given for long enough?

Many thanks again

Answer
Dear Jill

In most infections it is now recommended that antibiotics be only taken for two more days after symptoms disappear rather than the whole course. However, with C. difficile eradication is very important and faecal samples are usually taken to ensure this before cessation of therapy. So your hypothesis could very well be true in this case.

Regards

Alan galbraith

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