title: Experimental verification of the efficacy of optimized two-step infusion therapy with meropenem using an in vitro pharmacodynamic model and Monte Carlo simulation.
abstract: In this study we compared the efficacy of a theoretically optimized two-step infusion therapy (OTIT; rapid first-step infusion and slow second-step infusion) to the efficacies of prolonged infusion therapy (PIT) and traditional 0.5 h infusion therapy (TIT) with meropenem against Pseudomonas aeruginosa using an in vitro pharmacodynamic model and a Monte Carlo simulation. In the in vitro pharmacodynamic model, the bactericidal effect against P. aeruginosa was evaluated for 8 h, which is the usual dosing interval of meropenem. It was confirmed that the durability of the bactericidal effect of OTIT (0.25-1 g/0.5 h + 0.25-1 g/4 h t.i.d.) was almost equal to that of PIT and superior to that of TIT (0.5-2 g/0.5-4 h t.i.d.). In addition, the initial bactericidal effects of OTIT were superior to those of the prolonged 4 h infusion. In the Monte Carlo simulation study, the probability of target attainments (PTAs) of all dosing regimens of OTIT at MICs of 2-8 μg/ml were apparently superior to those of TIT and 4- and 6 h-PIT, when the target therapeutic condition for serious life-threatening infections was the achievement of both the percentage of the dosing interval at which the drug concentration exceeds the MIC (%T(>MIC)) ≥ 50% and the peak level divided by the MIC (Cmax/MIC) ≥ 4. Especially, the PTAs of the dosing regimens of 0.25-1 g/0.5 h + 0.25-1 g/4-6 h were excellent at MICs of 2-8 μg/ml. Against recent clinical isolates of P. aeruginosa in Japan, the dosing regimens of OTIT provided higher PTAs compared with those of TIT and 4- and 6 h-PIT. These results suggested that OTIT with sufficient pharmacokinetic conditions could be useful for enhancing the therapeutic efficacy of meropenem against serious life-threatening infections.
authors.affiliation: Pharmacology Research Laboratories, Dainippon Sumitomo Pharma Co., Ltd., Konohana-ku, Osaka, Japan. ken-eguchi@ds-pharma.co.jp
authors.forename: Ken
authors.initials: K
authors.lastname: Eguchi
authors.forename: Katsunori
authors.initials: K
authors.lastname: Kanazawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Shimizudani
authors.forename: Keiji
authors.initials: K
authors.lastname: Kanemitsu
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Kaku
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use*; D004334:Drug Administration Schedule; D006801:Humans; D007262:Infusions, Intravenous; D007564:Japan; D000077731:Meropenem; D008826:Microbial Sensitivity Tests; D009010:Monte Carlo Method; D011552:Pseudomonas Infections / Q000188:drug therapy; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D013845:Thienamycins / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use*
chemical_list: D000900:Anti-Bacterial Agents; D013845:Thienamycins; D000077731:Meropenem