How the drug dosing space and therapeutic level in term of MTD may best be correlated with pharmacokinetics and body metabolic rate in the subject to gain best possible impact and to minimize the toxicity.

when we recommend the dose of antibiotics like oxytetracycline in animals we usually take into consideration the recommended dose on the label but most of the time the therapeutic effect may not be obtained as suspected. As physician we recommend little bit high dose of the drug in some animals for best results which becomes beyond the regulation authorities to justify. 
Is it possible to recommend the dosing space or dose of the drug flexible including some criteria of considering BMR of the subject while prescribing MTD of drug in animals.
Analytical toxicology Biological modeling and pharmacokinetics Biomonitoring Biostatistics Clinical and translational toxicology
Ramesh Jayaraman
The therapeutic activity of Oxytetracyclines is dependent on the PK/PD index AUC/MIC. The AUC/MIC ratio of 15-20 is required for bacteriostatic activity in mice and in human patients against Staphylococcus aureus.
In your case, we need to know the following:
1. What is the animal ?
2. What is the PK of Oxytetracycline in the animal? ie, what is the dose, AUC, Cmax and t above MIC?
3. What is the infecting organism?
4. What is the MIC of Oxytetracycline on the the bacterium?
5. What is the MTD of Oxytetracycline in the animal?

In your case, the lack of efficacy observed in animals at the recommended dose Oxytetracycline could be because of inadequate PK, increased MIC. If the above data are available, the dose and dose frequency can be recommended. Although we can estimate the dose in the animal based on allometric scaling, we need to have information on PK and the MIC on the infecting organism.

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