Regulatory Guidelines on Dosage Selection for Efficacy

The scientific literature is replete with proposals for numerical values of these indices, for example, Cmax MIC90 10 1 for aminoglycosides, AUC MIC9o ratio 125 h for fluoroquinolones, and T MIC9o 50% for P-lactams. In fact, these values provide no more than a guide to clinically effective dosage for several reasons  

Target numerical values, in practice, are bug and drug -speciflc. 

The dosage required is dependent on bacterial load and level of immune competence of the host animal. 

The dosage required depends on whether the endpoint is clinical cure, bacteriological cure, or avoidance of emergence of resistance. 

For further discussion of these indices, see Lees et al. ° and Toutain et al.  

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