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Dear Sir
Can you please help me by elaborate the metabolism of Ciprofloxacin by CYP enzymes. If Ciprofloxacin
is an inhibitor of CYP1A2 then it means that by inhibiting CYP1A2 enzyme its concentration in plasma
increases, if yes then how. I have search for it but not successful. Waiting for your kind and
urgent reply.
Regards
Andleeb Shahzadi
Ph.D. Scholar,
Dept. Pharmacology & Clinical Pharmacology
Faculty of Medicine,
Istanbul University,
Istanbul, Turkey
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Dear andleeb,
If any drug is a inhibitor of any particular enzyme then it doesn't mean that by inhibiting that
enzyme you'll have higher plasma levels of same drug.
But yes,, if a drug is a substrate (getting metabolised by) of an enzyme and you give simultaneous
admin. Of enz. Inhibitor of that enzyme then you'll definitely have hike for that drug plasma
levels..
So make literature search in this direction for ciprofloxacin...
If you admin. Ciprofloxacin (1A2 inhibitor) and if you also admin. Drug X (1A2 substrate) then you
will have higher plasma levels of drug x but not of ciprofloxacin..
Hope this will help you little.
Kind regards,
Mitul Patel
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yes I know that if a drug is an inhibitor of that particular enzyme then it does not mean it
metabolized by the same inhibiting enzyme. But the question is that how Ciprofloxacin is metabolized
which enzymes are involved in its biotransformation. Please guide me
Regards
Andleeb Shahzadi
Ph.D. Scholar,
Dept. Pharmacology & Clinical Pharmacology
Faculty of Medicine,
Istanbul University,
Istanbul, Turkey
Andleeb shahzadi
--
... I'm not certain about the metabolism of ciprofloxacin itself, but the fact that it inhibits
CYP1A2 does not mean that it also metabolized by this enzyme. Best regards, Uwe FUhr
Uwe Fuhr
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Andleeb:
As you have already determined, there is not much information regarding ciprofloxacin elimination.
If you look at FDA-approved product labels, approximately 40-50% of an oral dosage is eliminated as
parent drug in the urine. Four metabolites are found in urine and together they "account for 15% of
an oral dose". There is minimal first pass metabolism.
The label for the IV formation states that 3 metabolites are found in urine and they account for
approximately 10% of an intravenous dose while 50-70% of a dose is excreted in the urine as parent.
Approximately 15% of an intravenous dose is found in feces. Very little unchanged drug is found in
bile.
One metabolic pathway is via sulfotransferase (Drug Metab Dispos. 2009 Aug;37(8):1711-7). The
mechanism by which ciprofloxacin inhibits CYP1A2 is not known. Specifically it is not known if
ciprofloxacin is metabolized and forms a metabolic-intermediate complex with 1A2. Some people
suspect ciprofloxacin is a time-dependent inhibitor of 1A2 because of the discrepancy between in
vitro data (weak inhibitor) and clinical data (more potent).
Sincerely,
Carol Collins
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