Pharmacokinetic-pharmacodynamic target attainment analysis of cefozopran in Japanese adult patients

A Systematic Review on Antimicrobial Pharmacokinetic Differences between Asian and Non-Asian Adult Populations

While the relevance of inter-ethnic differences to the pharmacokinetic variabilities of antimicrobials has been reported in studies recruiting healthy subjects, differences in antimicrobial pharmacokinetics between Asian and non-Asian patients with severe pathologic conditions require further investigation. For the purpose of describing the potential differences in antimicrobial pharmacokinetics between Asian and non-Asian populations, a systematic review was performed using six journal databases and six theses/dissertation databases (PROSPERO record CRD42018090054). The pharmacokinetic data of healthy volunteers and non-critically ill and critically ill patients were reviewed. Thirty studies on meropenem, imipenem, doripenem, linezolid, and vancomycin were included in the final descriptive summaries. In studies recruiting hospitalised patients, inconsistent differences in the volume of distribution (V_d) and drug clearance (CL) of the studied antimicrobials between Asian and non-Asian patients were observed. Additionally, factors other than ethnicity, such as demographic (e.g., age) or clinical (e.g., sepsis) factors, were suggested to better characterise these pharmacokinetic differences. Inconsistent differences in pharmacokinetic parameters between Asian and non-Asian subjects/patients may suggest that ethnicity is not an important predictor to characterise interindividual pharmacokinetic differences between meropenem, imipenem, doripenem, linezolid, and vancomycin. Therefore, the dosing regimens of these antimicrobials should be adjusted according to patients' demographic or clinical characteristics that can better describe pharmacokinetic differences.

[The Current State and Future Prospects of Population Pharmacokinetic Research in Post-marketing Clinical Studies in Japan]

Population pharmacokinetics (PPK) is a useful approach to the evaluation of drug pharmacokinetics in patients and is a widely used method for the evaluation of pharmacokinetics in clinical trials. PPK uses a statistical model to calculate population parameters, their variance, and covariates from sparse and unbalanced data in a large target population. Population parameters can subsequently be used to establish individual prescribing regimens for specific patients. Post-marketing clinical studies using PPK analysis have been reported by medical and academic institutions in order to complement the poor pharmacokinetics information, thus increasing the available pharmacokinetics information. However, because, in many cases, PPK information is not indicated in the package insert (PI), pharmacokinetics information such as pharmacokinetics parameters and associated variable factors is insufficient. We investigated what kind of new information was obtained in the post-marketing clinical studies using PPK analysis and whether these PPK results were described in Japan PI and/or interview form (IF). We showed that many post-marketing clinical studies were conducted as a single-center and observational study in order to supplement deficient pharmacokinetics data. Also, most PPK results obtained from post-marketing studies were not included in Japan PI and/or IF presumably due to lack of quality of PPK models. If sufficient post-marketing clinical studies using high-quality PPK models are performed, PPK models based on patients with diverse backgrounds, which take inter-individual variability into consideration, can be constructed and PPK information can contribute to the proper use of drugs and the promotion of individualized treatment strategies.

Stability of cefozopran hydrochloride in aqueous solutions

The influence of pH on the stability of cefozopran hydrochloride (CZH) was investigated in the pH range of 0.44-13.00. Six degradation products were identified with a hybrid ESI-Q-TOF mass spectrometer. The degradation of CZH as a result of hydrolysis was a pseudo-first-order reaction. As general acid-base hydrolysis of CZH was not occurred in the solutions of hydrochloric acid, sodium hydroxide, acetate, borate and phosphate buffers, kobs = kpH because specific acid-base catalysis was observed. Specific acid-base catalysis of CZH consisted of the following reactions: hydrolysis of CZH catalyzed by hydrogen ions (kH+), hydrolysis of dications (k1H2O), monocations (k2H2O) and zwitter ions (k3H2O) and hydrolysis of zwitter ions (k1OH-) and monoanions (k2OH-) of CZH catalyzed by hydroxide ions. The total rate of the reaction was equal to the sum of partial reactions: [Formula: see text]. CZH similarly like other fourth generation cephalosporin was most stable at slightly acidic and neutral pH and less stable in alkaline pH. The cleavage of the β-lactam ring resulting from a nucleophilic attack on the carbonyl carbon in the β-lactam moiety is the preferred degradation pathway of β-lactam antibiotics in aqueous solutions.

Pharmacokinetics of cefozopran by single and multiple intravenous infusions in healthy Chinese volunteers

BACKGROUND AND OBJECTIVES

Cefozopran is a parenteral cephalosporin with a broad spectrum of activity against Gram-positive and Gram-negative bacteria. The objective of this study was to evaluate the pharmacokinetics of cefozopran after single- and multiple-dose intravenous administration in healthy subjects, to provide clinical guidance in its application.

METHODS

This was a single-center, open-label, randomized, two-phase study conducted in 12 subjects. In the single-dose phase, subjects were randomly assigned to receive single doses of 0.5, 1.0 and 2.0 g of injected cefozopran hydrochloride in a three-way crossover design with a 5-day washout period between administrations. In the multiple-dose phase, subjects received 2.0 g every 12 h for 4 days. Plasma and urine pharmacokinetic samples were assayed by a validated high-performance liquid chromatography-tandem mass spectrometry method. Pharmacokinetic parameters were calculated and analyzed statistically. Safety assessments were conducted throughout the study.

RESULTS

Twelve healthy volunteers (six males and six females) were enrolled and completed the study. Following a single 1-h intravenous infusion of 0.5, 1.0 or 2.0 g cefozopran, maximum plasma concentration (C max) and area under the plasma concentration-time curve from time zero to the time of the last measurable concentration (AUClast) increased in a dose-proportional manner. The mean half-life in plasma (t ½) was in the range of 1.20-2.80 h. Cefozopran was mainly excreted in its unchanged form, with no tendency for accumulation, via the kidney, and varied from 65.99 to 73.33 %. No appreciable accumulation of either drug occurred with multiple intravenous doses of cefozopran, and pharmacokinetic parameters for cefozopran were similar on days 1 and 4. No serious adverse events were reported. Adverse events were generally mild.

CONCLUSION

Cefozopran was safe and well tolerated in the volunteers and displayed linear increases in the C max and AUClast values.