Safety, Tolerability, and Pharmacokinetics of a Novel Oral Phosphodiesterase 4 Inhibitor, ME3183: First-in-Human Phase 1 Study.

A novel, oral phosphodiesterase 4 (PDE4) inhibitor, ME3183, is under development for the treatment of psoriasis, atopic dermatitis, and other inflammatory diseases. To evaluate its safety, tolerability, and pharmacokinetics, double-blind, placebo-controlled, single ascending dose (SAD), and multiple ascending dose (MAD) phase 1 studies were conducted in 126 healthy adults. The food effect was evaluated in a randomized, open-label, crossover manner (n = 5). ME3183 was safe and tolerable up to 25 mg in the SAD part and up to 10 mg twice daily in the MAD part. Frequently observed treatment-emergent adverse events included diarrhea and headache, as commonly reported for approved PDE4 inhibitors, providing no novel safety concerns. Pharmacokinetic analysis showed dose-dependent increases in Cmax and AUC, with later tmax and longer t1/2 than apremilast, an approved PDE4 inhibitor. The food effect study showed slightly decreased systemic exposure. In the MAD part, plasma exposure levels of ME3183 were higher even at the minimal dose (2.5 mg twice daily) than the estimated therapeutically effective level. These results show the safe profile of ME3183 and support further studies to confirm the safety and efficacy of the drug in patients with psoriasis and other inflammatory diseases.

Pharmacokinetic-Pharmacodynamic Target Attainment Analyses To Support Dose Selection for ME1100, an Arbekacin Inhalation Solution.

ME1100 (arbekacin inhalation solution) is an inhaled aminoglycoside that is being developed to treat patients with hospital-acquired and ventilator-associated bacterial pneumonia (HABP and VABP, respectively). Pharmacokinetic-pharmacodynamic (PK-PD) target attainment analyses were undertaken to evaluate ME1100 regimens for the treatment of patients with HABP/VABP. The data used included a population pharmacokinetic (PPK) 4-compartment model with 1st-order elimination, nonclinical PK-PD targets from one-compartment in vitro and/or in vivo infection models, and in vitro surveillance data. Using the PPK model, total-drug epithelial lining fluid (ELF) concentration-time profiles were generated for simulated patients with varying creatinine clearance (CLcr) (ml/min/1.73 m2) values. Percent probabilities of PK-PD target attainment by MIC were determined based on the ratio of total-drug ELF area under the concentration-time curve (AUC) to MIC (AUC/MIC ratio) targets associated with 1- and 2-log10 CFU reductions from baseline for Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus Percent probabilities of PK-PD target attainment based on PK-PD targets for a 1-log10 CFU reduction from baseline at MIC values above the MIC90 value for K. pneumoniae (8 µg/ml), P. aeruginosa (4 µg/ml), and S. aureus (0.5 µg/ml) were ≥99.8% for ME1100 600 mg twice daily (BID) in simulated patients with CLcr values >80 to ≤120 ml/min/1.73 m2 ME1100 600 mg BID, 450 mg BID, and 600 mg once daily in simulated patients with CLcr values >50 to ≤80, >30 to ≤50, and 0 to ≤30 ml/min/1.73 m2, respectively, provided arbekacin exposures that best matched those for 600 mg BID in simulated patients with normal renal function. These data provide support for ME1100 as a treatment for patients with HABP/VABP.

Population Pharmacokinetic Analyses for Arbekacin after Administration of ME1100 Inhalation Solution.

ME1100, an inhalation solution of arbekacin, an aminoglycoside, is being developed for the treatment of hospital-acquired and ventilator-associated bacterial pneumonia. The objective of these analyses was to develop a population pharmacokinetic model to describe the arbekacin concentration-time profile in plasma and epithelial lining fluid (ELF) following ME1100 administration. Data were obtained from a postmarketing study for an intravenous (i.v.) formulation of arbekacin, a phase 1 study of ME1100 in healthy volunteers, and a phase 1b study of ME1100 in mechanically ventilated subjects with bacterial pneumonia. Data from the postmarketing study were utilized to develop a population pharmacokinetic model following i.v. administration, and this model was subsequently utilized as the foundation for development of the model characterizing arbekacin disposition following inhalation of ME1100. The final model utilized two compartments for both plasma and ELF disposition, with movement of arbekacin between the ELF and plasma parameterized using linear first-order rate constants. A bioavailability term was included for the inhalational route of administration, which was estimated to be 19.5% for a typical subject. The model included normalized creatinine clearance (CLcrn) and weight as covariates on arbekacin clearance: CL = (weight/52.2)0.855·[(CLcrn-77)·0.0289 + 2.32]. The model simultaneously described arbekacin concentrations following both i.v. and inhaled administration and provided acceptable fits to the plasma and ELF data (r2 of 0.922 and 0.557 for observed versus fitted concentrations, respectively). The developed model will be useful for conducting future analyses to support ME1100 dose selection.

[Pharmacokinetics analysis of tebipenem pivoxil in a phase II clinical trial in otolaryngological infections].

In a phase IIb clinical study (dose-finding test, 450 mg dosing group: 150 mg t.i.d., 500 mg dosing group: 250 mg b.i.d., 900 mg dosing group: 300 mg t.i.d.) of tebipenem pivoxil (TBPM-PI) for treatment of otolaryngological infections in adults, TBPM concentrations in the patient plasma were quantified. The primary pharmacokinetic parameters such as ka, kel, Vd/F and Tlag were estimated by the Bayesian method and then the secondary pharmacokinetic parameters such as tmax, Cmax, t1/2 and AUC were calculated. As for the patients whose primary parameters were not properly estimated by the Bayesian method, the secondary parameters were calculated by the trapezoidal method. The primary pharmacokinetic parameters obtained by the Bayesian method in 450 mg dosing group (150 mg t.i.d.), 500 mg dosing group (250 mg b.i.d.), and 900 mg dosing group (300 mg t.i.d.) were 5.64 +/- 2.76, 5.11 +/- 3.06 and 2.51 +/- 1.13 hr(-1) for ka, 1.75 +/- 0.25, 2.03 +/- 0.10 and 1.34 +/- 0.27 hr(-1) for kel, 17.62 +/- 5.09, 15.83 +/- 6.14 and 19.34 +/- 8.80 L for Vd/F, and 0.48 +/- 0.11, 0.38 +/- 0.03 and 0.39 +/- 0.26 hr for Tlag, respectively. The secondary parameters obtained by the Bayesian method and the trapezoidal method were 0.85 +/- 0.29, 0.81 +/- 0.33 and 1.18 +/- 1.53 hr for tmax, 5.08 +/- 2.05, 7.92 +/- 4.02 and 8.69 +/- 4.01 microg/ml for Cmax, 0.40 +/- 0.06, 0.34 +/- 0.01 and 0.54 +/- 0.10 hr for t1/2, 5.22 +/- 1.90, 7.93 +/- 4.04 and 13.62 +/- 6.29 microg x hr/ml for AUC after each dosing (AUC(0-8h) or AUC(0-12h)) and 15.65 +/- 5.70, 15.85 +/- 8.08 and 40.87+/- 18.87 microg x hr/ml for AUC(0-24h), respectively. As shown in the above, Cmax and AUC after each dosing were increased with a rise in the dose level, and AUC(0-24h) was increased with a rise in the total dose level per day. Regardless of the dosage, tmax was about 0.8-1.2 hr and t1/2 was about 0.3-0.5 hr, showing almost constant values. Changes in the regimen and dosage did not influence the pharmacokinetic properties of TBPM-PI. Pharmacokinetics of TBPM-PI in adult patients with otolaryngological infection were similar to those in healthy subjects.

Population pharmacokinetics of tebipenem pivoxil (ME1211), a novel oral carbapenem antibiotic, in pediatric patients with otolaryngological infection or pneumonia.

Tebipenem pivoxil (TBPM-PI, ME1211) has been under development as the world's first oral carbapenem for treatment of otolaryngological/respiratory infections caused by drug-resistant S. pneumoniae in pediatric patients. In order to treat these infections effectively, it is important to design optimal dosing regimens based on the pharmacokinetics/pharmacodynamics (PK/PD) relationships, which can be characterized by clarifying the pharmacokinetics of tebipenem (TBPM) in the pediatric population. We therefore performed an population pharmacokinetic analysis using plasma TBPM concentrations obtained from pediatric patients with otolaryngological infection or bacterial pneumonia (0.5-16 years old; n=217, 395 points), after repeated oral administration of TBPM-PI at a dose of 4 or 6 mg/kg b.i.d. A one-compartment model with first-order absorption was adopted. In analysis, weight-normalized creatinine clearance (Ccr) and age were the most significant covariates that respectively explained inter-subject variability in weight-normalized apparent clearance (CL/F) and volume of distribution (Vd/F) of TBPM. The CL/F of TBPM increased with Ccr, and the Vd/F decreased with age. Based on the results of the present analysis, validity of the presently recommended dosage regimen of TBPM-PI in pediatric patients is discussed.

Mrp2 is involved in benzylpenicillin-induced choleresis.

Benzylpenicillin (PCG; 180 micromol/kg), a classic beta-lactam antibiotic, was intravenously given to Sprague-Dawley (SD) rats and multidrug resistance-associated protein 2 (Mrp2)-deficient Eisai hyperbilirubinemic rats (EHBR). A percentage of the [(3)H]PCG was excreted into the bile of the rats within 60 min (SD rats: 31.7% and EHBR: 4.3%). Remarkably, a transient increase in the bile flow ( approximately 2-fold) and a slight increase in the total biliary bilirubin excretion were observed in SD rats but not in the EHBR after PCG administration. This suggests that the biliary excretion of PCG and its choleretic effect are Mrp2-dependent. Positive correlations were observed between the biliary excretion rate of PCG and bile flow (r(2) = 0.768) and more remarkably between the biliary excretion rate of GSH and bile flow (r(2) = 0.968). No ATP-dependent uptake of [(3)H]PCG was observed in Mrp2-expressing Sf9 membrane vesicles, whereas other forms of Mrp2-substrate transport were stimulated in the presence of PCG. GSH efflux mediated by human MRP2 expressed in Madin-Darby canine kidney II cells was enhanced in the presence of PCG in a concentration-dependent manner. In conclusion, the choleretic effect of PCG is caused by the stimulation of biliary GSH efflux as well as the concentrative biliary excretion of PCG itself, both of which were Mrp2 dependent.