What should be the possible reasons if we obtained more than 100% bioavailability of antibiotics (marbofloxacin) after I.M. and S.C. routes of administration in cattle species.
Hi,
In some species marbofloxacin exhibit flip-flop phenomenon after SC administration. It means the absorption phase is longer than elimination and affects Kel. In such a case you can see supra-bioavailability in your study. The question is did you see differences between Kel IV versus IM and/or SC. Of course please remember you can compare such values if your sampling was long enough - according to the roles. Some researchers make to short sampling and after that refer to "two-stage" elimination which is not true observation. So if you take samples long enough then it's possible to verify flip-flop.
Rules:
Article Comparison of bioequivalence study regulatory requirements f...
Example flip-flop:
Article Pharmacokinetics and bioavailability of Marbofloxacin in lam...
Finally, the question is about milking. If it was milking cows it could be a source of difference. Milk concentrations of marbofloxacin and disposition to the udder are dependent on the concentration of the drug in blood plasma. So after IV whole free fractions of the drug in plasma is available for distribution into the milk (it's quite a huge compartment) and for example when 12 hours after drug administration the cows are milked, whole that fraction is eliminated. But another situation is after SC or IM especially if the absorption process is long because finally after for example 12 h when cows are milked different fraction (in comparison to IV) is eliminated with milk.
For flip-flop verification:
First you should make comparison Kel between IV IM and SC
Next compare kab with Kel for IM and SC
It's only a general comment because I don't know the details of your study ....
Best regards,
Tomasz
Hi,
In some species marbofloxacin exhibit flip-flop phenomenon after SC administration. It means the absorption phase is longer than elimination and affects Kel. In such a case you can see supra-bioavailability in your study. The question is did you see differences between Kel IV versus IM and/or SC. Of course please remember you can compare such values if your sampling was long enough - according to the roles. Some researchers make to short sampling and after that refer to "two-stage" elimination which is not true observation. So if you take samples long enough then it's possible to verify flip-flop.
Rules:
Article Comparison of bioequivalence study regulatory requirements f...
Example flip-flop:
Article Pharmacokinetics and bioavailability of Marbofloxacin in lam...
Finally, the question is about milking. If it was milking cows it could be a source of difference. Milk concentrations of marbofloxacin and disposition to the udder are dependent on the concentration of the drug in blood plasma. So after IV whole free fractions of the drug in plasma is available for distribution into the milk (it's quite a huge compartment) and for example when 12 hours after drug administration the cows are milked, whole that fraction is eliminated. But another situation is after SC or IM especially if the absorption process is long because finally after for example 12 h when cows are milked different fraction (in comparison to IV) is eliminated with milk.
For flip-flop verification:
First you should make comparison Kel between IV IM and SC
Next compare kab with Kel for IM and SC
It's only a general comment because I don't know the details of your study ....
Best regards,
Tomasz
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