Single- and Repeated-Dose Pharmacokinetics of Ceftaroline in Plasma and Soft Tissues of Healthy Volunteers for Two Different Dosing Regimens of Ceftaroline Fosamil

Abstract

bCeftaroline fosamil (CPT-F) is currently approved for use for the treatment of complicated skin and soft tissue infections and community-acquired pneumonia at 600 mg twice daily (q12h), but other dosing regimens are under evaluation. To date, very limited data on the soft tissue pharmacokinetics (PK) of the active compound, ceftaroline (CPT), are available. CPT concentrations in the plasma, muscle, and subcutis of 12 male healthy volunteers were measured by microdialysis after single and repeated intravenous administration of 600 mg CPT-F q12h or three times daily (q8h) in two groups of 6 subjects each. Relevant PK and PK/pharmacodynamic (PD) parameters were calculated and compared between groups. In plasma, the area under the concentration-time curve (AUC) from 0 to 24 h for total CPT and the cumulative percentage of the dosing interval during which the free drug concentrations exceeded the MIC (fT MIC ) for unbound CPT for the currently established threshold of 1 mg/liter were significantly higher in the group receiving CPT-F q8h. Exposure to free drug in soft tissues was higher in the group receiving CPT-F q8h, but high interindividual variability in relevant PK parameters was observed. The mean ratios of the AUC from time zero to the end of the dosing interval (AUC 0-) for free CPT in soft tissues and the AUC 0-for the calculated free fraction in plasma at steady state ranged from 0.66 to 0.75. Administration of CPT-F q8h led to higher levels of drug exposure in all investigated compartments. When MIC values above 1 mg/liter were assumed, the calculated fT MIC after dosing q12h was markedly lower than that after dosing q8h. The clinical implications of these differences are discussed in light of recently completed clinical phase III and PK/PD studies. Ceftaroline fosamil (CPT-F; brand names, Zinforo in Europe and Teflaro in the United States) was recently approved by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for the treatment of complicated skin and soft tissue infections (cSSTIs) and community-acquired pneumonia (CAP) in adults. Ceftaroline (CPT) is a cephalosporin antibiotic and acts, like all beta-lactam agents, via inhibition of peptidoglycan synthesis. In contrast to other cephalosporins, CPT is active against some resistant microorganisms, such as methicillin-resistant Staphylococcus aureus (MRSA) and penicillin-nonsusceptible Streptococcus pneumoniae (PNSP), and is therefore often referred to as a "fifth generation," or advanced-generation, cephalosporin. CPT-F, a water soluble N-phosphono prodrug, is converted to the active CPT in human plasma, and CPT is further converted into the inactive ring-opened metabolite CPT M-1.Although CPT-F was shown to be effective against both approved indications, CAP and cSSTIs (1-5), precise information regarding the pharmacokinetics (PKs) of CPT in the interstitial space fluid of soft tissues is very limited to date. However, this information is considered to be highly relevant as a key input for PK/pharmacodynamic (PD) cal...

Ceftaroline fosamil doses and breakpoints forStaphylococcus aureusin complicated skin and soft tissue infections

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