Pharmacodynamics and pharmacokinetics of levofloxacin.

Principles of antibiotic pharmacodynamics include factors that are important for effective eradication of bacteria as well as the suppression of resistance. For effective eradication of bacteria and a good clinical outcome, a ratio for the area under the plasma concentration-time curve relative to the minimum inhibitory concentration (AUC/MIC) of greater than 100 is needed for gram-negative organisms, and a level of greater than 30 is required for gram-positive organisms. Pharmacodynamic principles can also be used to devise the optimal administration regimen for specific antimicrobial agents. Pharmacodynamic analysis of the activity of levofloxacin against Streptococcus pneumoniae revealed that, 99% of the time, actual hospitalized patients achieve an AUC/MIC of greater than 30. This indicates that levofloxacin will be very effective in treating S. pneumoniae infections in the majority of patients. Cost of treatment is an increasing concern voiced by healthcare providers and users alike. This has led to a much greater emphasis placed upon the cost of individual drugs used in the management of infections. However, when evaluating the cost of an antibiotic, it is extremely important that not only are the direct acquisition costs assessed, but consideration also given to other aspects incurring a financial burden, such as drug preparation cost, supplies, costs of treating adverse events or any treatment failures. It is only by having such a full assessment of costs that realistic financial comparisons can be made between different antibiotics.